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Title: Maxims and Instructions for the Boiler Room - Useful to Engineers, Firemen & Mechanics; Relating to Steam Generators, Pumps, Appliances, Steam Heating, Practical Plumbing, etc.
Author: Hawkins, N. (Nehemiah)
Language: English
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Text enclosed by underscores is in italics (_italics_).
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MAXIMS AND INSTRUCTIONS FOR THE BOILER ROOM.
[Illustration: HAWKINS’ EDUCATIONAL WORKS FOR ENGINEERS]
_This Work is Fraternally inscribed to W. R. Hawkins, R. F. Hawkins
and F. P. Hawkins._
[Illustration: RICHARD TREVITHICK.]
MAXIMS AND INSTRUCTIONS FOR THE BOILER ROOM.
Useful to Engineers, Firemen & Mechanics,
Relating to Steam Generators, Pumps,
Appliances, Steam Heating, Practical
Plumbing, etc.
[Illustration]
by
N. HAWKINS, M. E.,
Honorary Member National Association of Stationary Engineers, Editorial
Writer, Author of Hand Book of Calculations for Engineers and Firemen,
Etc., Etc.
Comprising Instructions and Suggestions on the Construction, Setting,
Control and Management of Various Forms of Steam Boilers; on the Theory
and Practical Operation of the Steam Pump; Steam Heating; Practical
Plumbing; also Rules for the Safety Valve, Strength of Boilers,
Capacity of Pumps, etc.
Theo. Audel & Co., Publishers,
63 Fifth Ave., Cor. 13th St.,
New York.
Copyrighted
1897—1898—1903
by
Theo, Audel & Co.
_PREFACE._
_The chief apology for the preparation and issue of these Maxims and
Instructions, for the use of Steam users, Engineers and Firemen, is the
more than kind reception of Calculations._
_But there are other reasons. There is the wholesome desire to benefit
the class, with whom, in one way and another, the author has been
associated nearly two score years._
_The plan followed in this work will be the same as that so generally
approved in Calculations; the completed volume will be a work of
reference and instruction upon those works set forth in the title page.
As a work of reference the work will be especially helpful through
combined Index and Definition Tables to be inserted at the close of the
book. By the use of these the meaning of every machine, material and
performance of the boiler room can be easily found and the “points” of
instruction made use of._
_This work being issued in parts, now in manuscript, and capable of
change or enlargement, the editor will be thankful for healthful
suggestions from his professional brethren, before it is put into
permanent book form._
[Illustration: OLIVER EVANS.
GEORGE STEPHENSON.
ROBERT FULTON.]
CONTENTS.
Page
PREFACE 7
INTRODUCTION 9
MATERIALS 12
Coal 13
Wood 14
Peat 14
Tan 15
Straw 15
Coke, Charcoal, Peat Charcoal 15
Liquid and Gas Fuels 15
Air 16
Table of Evaporation 18
Fire Irons 19
Handy Tools 21
The Tool Box 22
THE FIRING OF STEAM BOILERS 24
Directions for Firing with Various Fuels 28
Firing with Coke 28
Firing with Coal Tar 30
Firing with Straw 31
Firing with Oil 32
Firing on an Ocean Steamer 32
Firing of Sawdust and Shavings 33
Firing a Locomotive 36
Firing with Tan Bark 36
Points Relating to Firing 37
Foaming in Boilers 42
A CHAPTER OF DON’TS 44
STEAM GENERATORS 48
Description 49
An Upright Steam Boiler 50
The Growth of the Steam Boiler 52
Marine Boilers 60
The Surface Condenser 65
Operation of the Condenser 66
Water Tube Steam Boilers 67
Care of Water Tube Boilers 70
Sectional Boilers 71
Locomotive Boilers 72
Standard Horizontal Tubular Steam Boiler 79
Parts of the Tubular Boiler 81
The Triple Draught Tubular Boiler 83
SPECIFICATION FOR 125 HORSE POWER BOILER 85
Type 85
Dimensions 85
Quality and Thickness of Steel Plates 85
Flanges 85
Riveting 86
Braces 86
Manholes, Hand Holes and Thimbles 86
Lugs 86
Castings 86
Testing 87
Quality and Workmanship 87
Fittings and Mountings 87
Drawings 87
Duty of Boiler 87
MARKS ON BOILER PLATES 88
CONSTRUCTION OF BOILERS 89
Quality of Steel Plates 90
Nickel Steel Boiler Plates 91
Riveting 91
Bracing of Steam Boilers 96
Rule for Finding Pressure or Strain
on Bolts 99
Gusset Stays 100
Riveted or Screw Stays 101
Inspector’s Rules Relating to Braces in
Steam Boilers 102
Rules and Tables 105
Boiler Tubes 110
Portions of the Marine Boiler which
become Thin by Wear 112
EXAMPLES OF CONSTRUCTION AND DRAWING 113
Rule for Safe Internal Pressure 117
DEFINITION OF TERMS 121
Tensile strength 121
Contraction of area 121
Elongation 121
Shearing strength 121
Elastic limit 121
Tough 121
Ductile 121
Elasticity 122
Fatigued 122
Malleable 122
Weldable 122
Cold-short 122
Hot-short 122
Homogeneous 122
BOILER REPAIRS 123
Repairing Cracks 123
Defects and Necessary Repairs 124
Questions
by the Proprietor to the Engineer in
Charge, Relating to Condition of the
Boiler 127
Questions
asked of a Candidate For a Marine
License Relating to Defects in Boiler 127
THE INSPECTION OF STEAM BOILERS 129
How to prepare for Steam Boiler
Inspection 130
Issuing Certificates 131
The Hydraulic Test 131
ENGINEERS’ EXAMINATIONS 133
MECHANICAL STOKERS 134
CHEMICAL TERMS AND EXPLANATIONS
RELATING TO FEED WATERS 136
Chemistry 136
Element 136
Re-agent 136
Oxide 136
Carbonate 136
Acid 137
Alkalies 137
Chloride 137
Sulphates 137
Silica 137
Magnesia 138
Carbonate of Magnesia 138
Lime 138
Soda 138
Sodium 138
Salt 139
ANALYSIS OF FEED WATER 140
Directions 140
FROM ARGOS, IND. 140
FROM SIOUX FALLS, S. D. 140
FROM LITCHFIELD, ILL. 141
FROM CHELSEA, MASS. 141
FROM MEMPHIS, TENN. 141
FROM PEKIN, ILL. 141
FROM TIFFIN, OHIO 141
CORROSION AND INCRUSTATION OF STEAM BOILERS 142
Preliminary Precipitation of Water 144
A precipitator for Sea Water 145
Scale Deposited in Marine Boilers 146
A locomotive-Boiler Compound 149
“Points” Relating to the Scaling of
Steam Boilers 149
ENGINEERS’ TESTS FOR IMPURITIES IN
FEED WATER 153
Use of Petroleum Oil in Boilers 155
Kerosene Oil in Boilers 156
Mechanical Boiler Cleaners 159
Scumming Apparatus 161
Use of Zinc in Marine Boilers 162
BOILER FIXTURES AND BELONGINGS 164
Boiler Fronts 165
Furnace Doors 168
Fusible Plugs 171
Grate Bars 173
Water Gauge Cocks 176
Glass Gauges 177
The Mud Drum 179
Baffle Plates 180
Dead Plate 180
Steam Whistles 180
The Steam Gauge 181
Steam Separator 183
Sentinel Valve 184
Damper Regulators 185
Fuel Economizer and Feed Water Purifier 185
Safety Valves 187
U. S. Rules Relating to Safety Valves 189
Feed Water Heaters 196
Capacity of Cisterns 202
Water Meters 203
“Points” Relating to Water Meters 204
The Steam Boiler Injector 206
“Points” Relating to the Injector 209
LAWS OF HEAT 212
THE STEAM PUMP 215
Classification of Pumps 217
Points Relating to Pumps 219
Calculations Relating to Pumps 222
IMPORTANT PRINCIPLES RELATING TO WATER 224
STORING AND HANDLING OF COAL 225
CHEMISTRY OF THE FURNACE 226
Oxygen 229
Carbon 229
Hydrogen 230
Nitrogen 230
Sulphur 230
Carbonic Acid Gas 230
Carbonic Oxide 231
Table 231
HEATPROOF AND ORNAMENTAL PAINTS 232
PRESSURE RECORDING GAUGE 233
HORSE POWER AS APPLIED TO BOILERS 234
Rule For Estimating Horse Power of
Horizontal Tubular Steam Boilers 235
BOILER SETTING 236
Setting of Water Tube Boilers 239
Points Relating to Boiler Setting 239
KINDLING A FURNACE FIRE 241
Sawdust Furnace 242
PIPES AND PIPING 244
Joints of Pipes and Fittings 248
STEAM AND HOT WATER HEATING 251
Points Relating to Steam Heating 254
Ventilation 265
Heating by Exhaust Steam 267
Care of Steam Fittings 268
Tools used in Steam Fitting 269
Cocks 270
Valves 271
Steam Fittings 274
Steam Pipe and Boiler Coverings 275
Linear Expansion of Steam Pipes 276
The Steam Loop 278
BOILER MAKERS’ TOOLS AND MACHINERY 281
STEAM 282
WATER HAMMER 283
HAZARDS OF THE BOILER ROOM 285
Fuel Oil 289
WATER CIRCULATION 294
CHIMNEYS AND DRAUGHT 296
PLUMBING 298
Piping and Drainage 299
Lead Pipe Joints 300
Repairing Pipes with Putty Joints 303
Bending Lead Pipe 304
Plumber’s Solder 305
Plumber’s Tools 306
USEFUL TABLES OF WEIGHTS OF IRON AND
COMPARISONS OF GAUGES 309
NOISELESS WATER HEATER 312
ACCIDENTS AND EMERGENCIES 313
Burns and Scalds 313
Glue Burn Mixture 315
Insensibility from Smoke 315
Heat-stroke or Sun-stroke 316
Cuts and Wounds 316
Bleeding 317
Frost Bite 318
Broken Bones 318
Poultices 319
How to Carry an Injured Person 319
PERSONAL 320
INDEX 321
ADVERTISMENTS 333
INTRODUCTION.
Each successive generation of engineers has added certain _unwritten
experiences_ to the general stock of knowledge relating to steam
production, which have been communicated to their successors, and by
them added to, in their turn; it is within the province of this book to
put in form for reference, these unwritten laws of conduct, which have
passed into MAXIMS among engineers and firemen—a maxim being
an undisputed truth, expressed in the shortest terms.
SOLILOQUY OF AN ENGINEER. “Standing in the boiler room and looking
around me, there are many things I ought to know a good deal
about. Coal! What is its quality? How much is used in ten hours or
twenty-four hours? Is the grate under the boiler the best for an
economical consumption of fuel? Can I, by a change in method of
firing, save any coal? The safety-valve. Do I know at what pressure
it will blow off? Can I calculate the safety-valve so as to be
certain the weight is placed right? Do I know how to calculate the
area of the grate, the heating surface of the tubes and shell? Do
I know the construction of the steam-gauge and vacuum-gauge? Am I
certain the steam-gauge is indicating correctly, neither over nor
under the pressure of the steam? What do I know about the setting
of boilers? About the size and quality of fire bricks? About the
combination of carbon and hydrogen of the fuel with the oxygen of the
atmosphere? About oxygen, hydrogen and nitrogen? About the laws of
combustion? About radiation and heat surfaces?
“Do I know what are good non-conductors for covering of pipes, and
why they are good? Do I know how many gallons of water are in the
boiler?
“What do I know about water and steam? How many gallons of water are
evaporated in twenty-four hours? What do I know about iron and steel,
boiler evaporation, horse power of engines, boiler appendages and
fittings.
“Can I calculate the area and capacity of the engine cylinder? Can I
take an indicator diagram and read it? Can I set the eccentric? Can
I set valves? Do I understand the construction of the thermometer,
and know something about the pressure of the atmosphere, temperature
and the best means for ventilation? Can I use a pyrometer and a
salinometer?
“Without going outside of my boiler and engine room I find these
things are all about me—air, water, steam, heat, gases, motion,
speed, strokes and revolutions, areas and capacities—how much do I
know about these?
“How much can be learned from one lump of coal? What was it, where
did it come from? When it is burned, what gases will it give off?
“And so with water. What is the composition of water? What are
the effects of heat upon it? How does it circulate? What is the
temperature of boiling water? What are the temperatures under
different pressures? What is latent heat? What is expansive force?”
These are the questioning thoughts which fill, while on duty, more
or less vividly, the minds of both engineers and firemen, and it is
the purpose of this volume to answer the enquiries, as far as may
be without attempting too much; for the perfect knowledge of the
operations carried on within the boiler-room involves an acquaintance
with many branches of science. In matters relating to steam
engineering, it must be remembered that “art is long and time is short.”
The utility of such a book as this is intended to be, no one will
question, and he who would not be a “hewer of wood and a drawer of
water” to the more intelligent and well-informed mechanic, must possess
to a considerable extent the principles and rules embraced in this
book; and more especially, if he would be master of his profession and
reputed as one whose skill and decisions can be implicitly relied upon.
The author in the preparation of the work has had two objects
constantly in view; first to cause the student to become familiarly
acquainted with the leading principles of his profession as they
are mentioned, and secondly, to furnish him with as much advice and
information as possible within the reasonable limits of the work.
While it is a fact that some of the matter contained in this work is
very simple, and all of it intended to be very plain, it yet remains
true that the most expert living engineer was at one time ignorant of
the least of the facts and principles here given, and at no time in
his active career can he ever get beyond the necessity of knowing the
primary steps by which he first achieved his success.
The following taken from the editorial columns of the leading
mechanical journal of the country contains the same suggestive ideas
already indicated in the “soliloquy of an engineer:”
“There is amongst engineers in this country a quiet educational
movement going on in matters relating to facts and principles
underlying their work that is likely to have an important influence
on industrial affairs. This educational movement is noticeable in
all classes of workmen, but amongst none more than among the men in
charge of the power plants of the country. It is fortunate that this
is so, for progress once begun in such matters is never likely to
stop.
“Engineers comprise various grades from the chief engineer of some
large establishment, who is usually an accomplished mechanic,
carrying along grave responsibilities, to the mere stopper and
starter, who is engineer by courtesy only, and whose place is likely
to be soon filled by quite another man, so far as qualifications are
concerned. Men ignorant of everything except the mere mechanical
details of their work will soon have no place.
“Scarcely a week passes that several questions are not asked by
engineers, either of which could be made the subject of a lengthy
article. This is of interest in that it shows that engineers, are not
at the present time behind in the way of seeking information. Out of
about a thousand questions that went into print, considerable more
than half were asked by stationary engineers. These questions embrace
many things in the way of steam engineering, steam engine management,
construction, etc.”
The old meaning of the word lever was “a lifter” and this book is
intended to be to its attentive student, a real lever to advance him
in his life work; it is also to be used like a ladder, which is to be
ascended step by step, the lower rounds of which, are as important as
the highest.
It is moreover, the earnest wish of the editor that when some,
perchance may have “climbed up” by the means of this, his work, they
may in their turn serve as lifters to advance others, and by that means
the benefits of the work widely extended.
MATERIALS.
_The things with which the engineer has to deal in that place where
steam is to be produced as an industrial agent, are_
_1. The Steam Generator._
_2. Air._
_3. Fuel._
_4. Water._
_5. Steam Appliances._
_Starting with these points which form a part of every steam plant,
however limited, however vast, the subject can easily be enlarged
until it embraces a thousand varied divisions extending through all
time and into every portion of the civilized world._
_It is within the scope of this work to so present the subjects
specified, that the student may classify and arrange the matter into
truly scientific order._
MATERIALS.
In entering the steam department, where he is to be employed, the eye
of the beginner is greeted with the sight of coal, water, oil, etc.,
and he is told of invisible materials, such as air, steam and gases; it
is the proper manipulation of these seen and unseen material products
as well as the machines, that is to become his life task. In aiding
to the proper accomplishment of the yet untried problems nothing can
be more useful than to know something of the nature and history of
the different forms of matter entering into the business of steam
production. Let us begin with
COAL.
The source of all the power in the steam engine is stored up in coal in
the form of heat.
And this heat becomes effective by burning it, that is, by its
combustion.
Coal consists of carbon, hydrogen, nitrogen, sulphur, oxygen and ash.
These elements exist in all coals but in varying quantities.
These are the common proportions of the best sorts:
=========+============+============+===========+========+========
| | | WOOD | | PEAT
| ANTHRACITE | BITUMINOUS | (AVERAGE) | PEAT | 1/4
| | | DRY. | | WATER
---------+------------+------------+-----------+--------+--------
Carbon | 90-1/2 | 81 | 50 | 59 | 44
Hydrogen | 2-1/2 | 5-1/4 | 6 | 6 | 4-1/2
Nitrogen | 0-1/4 | 1 | 1 | 1-1/4 | 1
Sulphur | 00 | 1-1/2 | 0 | ? | (25)
Oxygen | 2-1/2 | 6-1/2 | 41 | 30 | 22-1/2
Ash | 4-1/4 | 4-3/4 | 2 | 3-3/4 | 3
| ----- | ------ | ------ | ------ |--------
| 100 | 100 | 100 | 100 | 100
In burning coal or other fuel atmospheric air must be introduced before
it will burn; the air furnishes the oxygen, without which combustion
cannot take place.
It is found that in burning one lb. of coal one hundred and fifty cubic
feet of air must be used and in every day practice it is necessary to
supply twice as much; this is supplied to the coal partly through the
grate bars, partly through the perforated doors, and the different
devices for applying it already heated to the furnace.
WOOD.
Wood as a combustible, is divisible into two classes: 1st, the hard,
compact and comparatively heavy, such as oak, ash, beech, elm. 2d,
the light colored soft, and comparatively light woods as pine, birch,
poplar.
Wood when cut down contains nearly half moisture and when kept in a dry
place, for several years even, retains from 15 to 20 per cent. of it.
The steam producing power of wood by tests has been found to be but
little over half that of coal _and the more water in it the less its
heating power_. In order to obtain the most heating power from wood it
is the practice in some works in Europe where fuel is costly, to dry
the wood fuel thoroughly, even using stoves for the purpose, before
using it. This “hint” may serve a good purpose on occasion.
The composition of wood reduced to its elementary condition will be
found in the table with coal.
PEAT.
Peat is the organic matter or vegetable soil of bogs, swamps and
marshes—decayed mosses, coarse grasses, etc. The peat next the
surface, less advanced in decomposition, is light, spongy and fibrous,
of a yellow or light reddish-brown color; lower down it is more
compact, of a darker-brown color, and in the lowest strata it is of a
blackish brown, or almost a black color, of a pitchy or unctuous feel.
Peat in its natural condition generally contains from 75 to 80 per
cent. of water. It sometimes amounts to 85 or 90 per cent. in which
case the peat is of the consistency of mire.
When wet peat is milled or ground so that the fibre is broken, crushed
or cut, the contraction in drying is much increased by this treatment;
and the peat becomes denser, and is better consolidated than when
it is dried as it is cut from the bog; peat so prepared is known as
_condensed_ peat, and the degree of condensation varies according to
the natural heaviness of the peat. So effectively is peat consolidated
and condensed by the simple process of breaking the fibres whilst wet,
that no merely mechanical force of compression is equal to it.
In the table the elements of peat are presented in two conditions. One
perfectly dried into a powder before analyzing and the other with 25
per cent. of moisture.
The value of peat as a fuel of the future is an interesting problem in
view of the numerous inroads made upon our great natural coal fields.
TAN.
Tan, or oak bark, after having been used in the process of tanning is
burned as fuel. The spent tan consists of the fibrous portion of the
bark. Five parts of oak bark produce four parts of dry tan.
STRAW.
Two compositions of straw (as a fuel) is as follows:
Water, 14 per cent.
Combustible matter, 79 „
Ash, 7 „
COKE, CHARCOAL, PEAT CHARCOAL.
These are similar substances produced by like processes from coal,
wood, and peat and they vary in their steam-producing power according
to the power of the fuels from which they are produced. The method by
which they are made is termed carbonization, which means that all the
gases are removed by heat in closed vessels or heaps, leaving only the
carbon and the more solid parts like ashes.
LIQUID AND GAS FUELS.
Under this head come petroleum and coal gas, which are obtained in
great variety and varying value from coal and coal oil. The heating
power of these fuels stands in the front rank, as will be seen by the
table annexed.
There are kinds of fuel other than coal, such as wood, coke, sawdust,
tan bark, peat and petroleum oil and the refuse from oil. These are all
burned with atmospheric air of which the oxygen _combines_ with the
combustible part of the fuel while the nitrogen passes off into the
chimney as waste.
The combustible parts of coal are carbon, hydrogen and sulphur and
the unburnable parts are nitrogen, water and the incombustible solid
matters such as ashes and cinder. In the operation of firing under a
boiler the three first elements are totally consumed and form heat; the
nitrogen, and water in the form of steam, escapes to the flue, and the
ashes and cinders fall under the grates.
The anthracite coal retain their shape while burning, though if too
rapidly heated they fall to pieces. The flame is generally short, of a
blue color. The coal is ignited with difficulty; it yields an intense
local or concentrated heat; and the combustion generally becomes
extinct while yet a considerable quantity of the fuel remains on the
grate.
The dry or free burning bituminous coals are rather lighter than
the anthracites, and they soon and easily arrive at the burning
temperature. They swell considerably in coking, and thus is facilitated
the access of air and the rapid and complete combustion of their fixed
carbon.
The method of firing with different sorts of fuel will be treated
elsewhere.
AIR.
The engineer’s success in the management of the furnace depends quite
as much upon his handling the air in the right mixtures and proportions
as it does in his using the fuel—for
1. Although invisible to the eye air is as much _a material substance_
as coal or stone. If there were an opening into the interior of the
earth which would permit the air to descend its density would increase
in the same manner at it diminishes in the opposite direction. At the
depth of about 34 miles it would be as dense as water, and at the depth
of 48 miles it would be as dense as quicksilver, and at the depth of
about 50 miles as dense as gold.
2. Air is not only a substance, but _an impenetrable body_; as for
example: if we make a hollow cylinder, smooth and closed at the bottom,
and put a stopper or solid piston to it, no force will enable us to
bring it into contact with the bottom of the cylinder, unless we permit
the air within it to escape.
3. Air is _a fluid_ which is proved by the great movability of its
parts, flowing in all directions in great hurricanes and in gentle
breezes; and also by the fact that a pressure or blow is propagated
through all parts and affects all parts alike.
4. It is also an _elastic fluid_, thus when an inflated bladder is
compressed it immediately restores itself to its former situation;
indeed, since air when compressed restores itself or tends to restore
itself, with the same force as that with which it is compressed, it is
a perfectly elastic body.
5. The weight of a column of air one square foot at the bottom is found
to be 2156 lbs. or very nearly 15 lbs. to the square inch, hence it is
common to state the pressure of the atmosphere as equal to 15 lbs. to
the square inch.
_It follows from these five points that the engineer must consider air
as a positive, although unseen, factor with which his work is to be
accomplished._
What air is composed of is a very important item of knowledge. It
is made of a _mixture_ of two invisible gases whose minute and
inconceivably small atoms are mingled together like a parcel of marbles
and bullets—that is while together they do not lose any of their
distinctive qualities. The two gases are called nitrogen and oxygen,
and of 100 parts or volumes of air 79 parts are of nitrogen and 21
parts of oxygen; but _by weight_ (for the oxygen is the heaviest) 77 of
nitrogen and 23 of oxygen.
The oxygen is the part that furnishes the heat by uniting with the
coal—indeed without it the process of combustion would be impossible:
of the two gases the oxygen is burned in the furnace, more or less
imperfectly, and the nitrogen is wasted.
TABLE OF EVAPORATION.
In order to arrive at the money value of the various fuels heretofore
described a method of composition has been arrived at which gives
very accurately their comparative worth. The rule is too advanced for
this elementary work, but the following results are plainly to be
understood, and will be found to be of value.
Lbs. of Fuel. Temperature of Water 212°
Coal, 14.62 lbs of Water.
Coke, 14.02 „
Wood, 8.07 „
Wood; 25% of water, 6.05 „
Wood Charcoal, 13.13 „
Peat, perfectly dry, 10.30 „
Peat, with 25% moisture, 7.41 „
Peat, Charcoal (dry), 12.76 „
Tan, dry, 6.31 „
Tan, 30% moisture, 4.44 „
Petroleum, 20.33 „
Coal gas 1 lb. or (31-1/3 cub. feet) 47.51 „
The way to read this table is as follows: “one lb. coal has an average
evaporative capacity of 14.62 lbs. of water,” or
One lb. of peat with one-quarter moisture will evaporate, if _all_ the
heat is utilized 7.41 lbs. of water.
In practice but little over half of these results are attained, but for
a matter of comparison of the value of one kind of fuel with another
the figures are of great value; a boiler burning wood or tan needs to
be much larger than one burning petroleum oil.
FIRE IRONS.
The making or production of steam requires the handling of the fuel,
more or less, until its destruction is complete, leaving nothing behind
in the boiler room, except ashes and clinkers. The principal tools used
by the attendant, to do the task most efficiently are: 1. The scoop
shovel. 2. The poker. 3. The slice bar. 4. The barrow.
[Illustration: Fig. 1.]
Fig. 1. represents the regular scoop shovel commonly called “a coal
shovel,” but among railroad men and others, known as a locomotive or
charging scoop. The cut also represents a regular shovel. Both these
are necessary for the ordinary business of the boiler room.
[Illustration: Fig. 2.]
In cut 2 are represented a furnace poker, A, and two forms of the slice
bar. They are all made by blacksmiths from round iron, some 7 or 8
feet long and only vary in the form of the end. The regular slice bar
is shown in C, Fig. 2; and “the dart” a special form used largely on
locomotives is shown in B.
The dexterous use of these important implements can merely be indicated
in print, as it is part of the trade which is imparted by oral
instruction. One “point” in making the slice bar may be mentioned to
advantage—the lower side should be perfectly flat _so that it may
slide_ on the surface of the grate bars as it is forced beneath the
fire—and the upper portion of the edge should be in the shape of a half
wedge, so as to crowd upwards the ashes and clinkers while the lower
portion slides along.
There is sometimes used in connection with these tools an appliance
called a LAZY BAR. This is very useful for the fireman when cleaning a
bituminous or other coal fire: it saves both time and fuel as well as
steam. It is a hook shaped iron, ingeniously attached above the furnace
door, so that it supports the principal part of the weight of the heavy
slice bar or poker when being used in cleaning out the fires.
[Illustration: Fig. 3.]
Equally necessary to the work of the boiler-room is the barrow shown in
cut. There are many styles of the vehicle denominated respectively—the
railroad barrow, the ore and stone barrow, the dirt barrow, etc.; but
the one represented in fig. 3 is the regular coal barrow.
In conveying coal to “batteries” of boilers, in gas houses and other
suitable situations the portable car and iron track are nearly always
used instead of the barrow. In feeding furnaces with saw dust and
shavings large iron screw conveyors are frequently employed, as well
as blowers—In the handling of the immense quantities of fuel required,
the real ingenuity of the engineer in charge has ample opportunity for
exercise.
There are also used in nearly all boiler rooms HOES made of heavy plate
iron, with handles similar to those shown in the cuts representing the
slice bar and poker. A set of two to four hoes of various sizes is a
very convenient addition to the list of fire tools; a light garden hoe
for handling ashes is not to be omitted as a labor saving tool.
HANDY TOOLS.
Besides the foregoing devices for conducting the preliminary process
of the steam generation, the attendant should have close at hand a
servicable HAND HAMMER, a SLEDGE for breaking coal and similar work,
and A SCREW WRENCH and also a light LADDER for use about the boiler and
shafting.
In addition to these there are various other things almost essential
for the proper doing of the work of the boiler room,—FIRE AND WATER
PAILS, LANTERNS, RUBBER HOSE, etc., which every wise steam user will
provide of the best quality and which the engineer will as carefully
keep in their appointed places ready for instant service.
[Illustration: Fig. 4.]
To these familiar tools can be added FILES, LACE CUTTERS, BOILER-FLUE
BRUSHES, STOCK and DIES, PIPE-TONGS, SCREW JACKS, VISES, etc., all of
which when used with skill and upon right occasion pay a large return
on their cost.
THE TOOL BOX.
The complex operations of the boiler room, its emergencies and varying
conditions demand the use of many implements which might at first
thought be out of place. The following illustrations exhibit some of
these conveniences.
[Illustration: Fig. 5.]
Fig. 5, letter A, show the common form of COMPASSES which are
made from 3 to 8 inches long. Letter B, illustrates the common steel
compass dividers, which are made from 5 to 24 inches in length.
[Illustration: Fig. 6.]
In this illustration, A exhibits double, inside and outside
CALIPERS; B, adjustable outside Calipers; C, inside; and D
outside, plain calipers.
[Illustration: Various Tools.]
THE FIRING OF STEAM BOILERS.
The care and management of a steam boiler comprises three things:
1. The preparation, which includes the partial filling with water and
the kindling of the fire.
2. The running, embracing the feeding, firing and extinction or banking
of the fire.
3. The cleaning out after it has been worked for some time.
To do this to the best advantage, alike to owner and employee, can be
learned only by practice under the tuition of an experienced person.
The “trick” or unwritten science of the duties of the skillful fireman
must be communicated to the beginner, by already experienced engineers
or firemen or from experts who have made the matter a special study.
_Let it be understood that the art of firing cannot be self taught._
The importance of this knowledge is illustrated by a remarkable
difference shown in competitive tests in Germany between trained and
untrained firemen in the matter of securing a high evaporation per
pound of coal. The trained men succeeded in evaporating 11 lbs. of
water, as against 6.89 lbs. which was the best that the untrained men
could obtain.
It is certain that a poor fireman is a dear man at any price, and that
a competent one may be cheap at twice the wages now paid. Suppose,
for instance, a man who burns three tons a day is paid $2.00 for such
service, and that in so doing he is wasting as little as 10 per cent.
If the coal cost $4.50 per ton the loss will be $1.35 per day, or what
is equivalent to paying a man $3.35 per day who can save this amount.
The late Chief Engineer of Philadelphia Water Works effected an annual
saving to the city of something like $50,000; and recently the weekly
consumption of a well established woolen mill was reduced from 71 to 49
tons, a clear saving of 22 tons by careful attention to this point.
It is apparent that any rules or directions which might be given for
one system would not apply equally to other forms of boilers and this
may be the principal reason that the art is one so largely of personal
instruction. Some rules and hints will, however, be given to the
beginner, which may prove of advantage in fitting the fireman for an
advanced position; or to assure him permanence in his present one.
_No two boilers alike._ It is said that no two boilers, even though
they seemed to be exactly alike—absolute duplicates—ever did the same,
or equal service. Every steam boiler, like every steam engine, has an
individuality of its own, with which the person in charge has to become
acquainted, in order to obtain the best results from it.
The unlikeness in the required care of steam engines which seem to
be exactly the same, is still more marked in the different skill
and experience demanded in handling locomotive, marine, stationary,
portable boilers and other forms of steam generators.
BEFORE LIGHTING THE FIRE under the boiler in the morning, the engineer
or fireman should make a rapid yet diligent examination of various
things, viz.: 1. He should make sure that the boiler has the right
quantity of water in it—that it has not run out during the night or
been tampered with by some outside party; very many boilers have been
ruined by neglecting this first simple precaution. 2. He should see
that the safety-valve is in working order; this is done by lifting by
rod or hand the valve which holds the weight upon the safety valve rod.
3. He should open the upper gauge-cock to let out the air from the
boiler while the steam is forming. 4. He should examine the condition
of the grate-bars and see that no clinkers and but few ashes are left
from last night’s firing. 5. And finally, after seeing that everything
is in good shape, proceed to build the fire as follows:
ON LIGHTING THE FIRE. When quite certain that everything is in good
condition, put a good armful of shavings or fine wood upon the grate,
then upon this some larger pieces of wood to form a bed of coals, and
then a little of the fuel that is to be used while running. Sometimes
it is better to light before putting on the regular fuel, but in any
case give it plenty of air. Close the fire doors, and open the ash pit,
giving the chimney full draught.
When the fire is well ignited, throw in some of the regular fuel, and
when this is burning add more, a little at a time, and continue until
the fire is in its normal condition, taking care, however, not to let
it burn too freely for fear of injury to the sheets by a too rapid
heating.
It is usually more convenient to light the fire through the fire door,
but where this cannot be done, a torch may be used beneath the grates,
or even a light fire of shavings may be kindled in the ash pit.
At the time of lighting, all the draughts should be wide open.
As soon as the steam is _seen_ to issue from the open upper gauge-cock
it is proof that the air is out. It should now be closed and the steam
gauge will soon indicate a rise in temperature.
When the steam begins to rise it should next be observed that: 1. All
the cocks and valves are in working order—that they move easily. 2.
That all the joints and packings are tight.
In the following two cuts are exhibited in an impressive way the
difference between proper and improper firing.
[Illustration: Fig. 1.]
Fig. 1 represents the proper mode of keeping an even depth of coal on
the grate bars; the result of which will be, a uniform generation of
gas throughout the charge, and a uniform temperature in the flues.
[Illustration: Fig. 2.]
Fig. 2 represents a very frequent method of feeding furnaces; charging
the front half as high, and as near the door, as possible, leaving the
bridge end comparatively bare. The result necessarily is that more
air obtains access through the uncovered bars than is required, which
causes imperfect combustion and consequent waste.
The duties of the fireman in the routine of the day may thus be summed
up:
1st.—_Begin to charge the furnace at the bridge end and keep firing to
within a few inches of the dead plate._
2d.—_Never allow the fire to be so low before a fresh charge is thrown
in, that there shall not be at least three to five inches deep of
clean, incandescent fuel on the bars, and equally spread over the
whole._
3d.—_Keep the bars constantly and equally covered_, particularly at the
sides and the bridge end, where the fuel burns away most rapidly.
4th.—If the fuel burns unequally or into holes, _it must be leveled,
and the vacant spaces must be filled_.
5th.—The large coals must be broken into pieces not bigger than a man’s
fist.
6th.—When the ash pit is shallow, it must be the more frequently
cleared out. A body of hot cinders, beneath them, overheats and burns
the bars.
7th.—The fire must not be hurried too much, but should be left to
increase in intensity gradually. When fired properly the fuel is
consumed in the best possible way, no more being burned than is needed
for producing a sufficient quantity of steam and keeping the steam
pressure even.
DIRECTIONS FOR FIRING WITH VARIOUS FUELS.
FIRING BOILERS NEWLY SET, ETC.—Boilers newly set should be heated up
very slowly indeed, and the fires should not be lighted under the
boilers for at least two weeks after setting, if it is possible to wait
this length of time. This two weeks enables all parts of the mason work
to set gradually and harden naturally; the walls will be much more
likely to remain perfect than when fires are lighted while the mortar
is yet green.
When fire is started under a new boiler the first time, it should
be a very small one, and no attempt should be made to do more than
moderately warm all parts of the brick work. A slow fire should be kept
up for twenty-four hours, and on the second day it may be slightly
increased. Three full days should elapse before the boiler is allowed
to make any steam at all.
When the pressure rises, it should not be allowed to go above four or
five pounds, and the safety valve weight should be taken off to prevent
any possibility of an increase. Steam should be allowed to go through
all the pipes attached for steam, and blow through the engine before
any attempt is made to get pressure on them. The object of all these
precautions and this care is to prevent injury by sudden expansion,
which may cause great damage.
FIRING WITH COKE.
Coke, in order to be completely consumed, needs a greater volume of
air per pound of fuel than coal. Theoretically it needs from 9 to 10
lbs. of air to burn a pound of coal, and 12 to 13 lbs. of air to burn a
pound of coke.
Coke, therefore, requires a more energetic draft, which is increased by
the fact that it can only burn economically in a thick bed. It is also
necessary to take into account the size of the pieces.
The ratio between the heating and grate surface should be less with
coke than with coal; that is to say, the grate should be larger.
The difference amounts to about 33 per cent. In fact, about 9-3/4 lbs.
of coke should be burned per hour on each square foot of grate area,
while at least 14-1/2 lbs. of coal can be burned upon the same space.
The high initial temperature which is developed by the combustion of
coke requires conducting walls. Therefore the furnace should not be
entirely surrounded by masonry; and the plates of the boiler should
form at least the crown of the fire-box. In externally fired boilers,
the furnace should be located beneath and not in front of the boiler.
Internal fire-boxes may be used, but the greatest care should be
exercised to avoid any incrustation of the plates, and in order that
this may be done, only the simplest forms of boilers should be used.
With coke it is not essential that long passages should be provided for
the passage of the products of combustion, since the greater part of
the heat developed is transmitted to the sheets in the neighborhood of
the furnace.
Since coke contains very little hydrogen, the quick flaming combustion
which characterizes coal is not produced, but the fire is more even and
regular. And, finally, the combustion of coal is distinguished by the
fact that in the earlier phases there is usually an insufficiency of
air, while in the last there is no excess.
The advantage of coke over raw soft coal as a fuel is that otherwise
useless slack can be made available by admixture in its manufacture,
and especially that it can be perfectly and smokelessly burnt without
the need of skilled labor. And we cannot doubt that the public demand
for a clear and healthy atmosphere will finally result in the almost
complete substitution of coke fuel for soft lump coal.
SIXTEEN STEAM BOILERS in a large mill in Massachusetts of 54 and 60
inches in diameter are fired as follows:
There are three separate batteries; one of five boilers, one of eight
and one of three. Each boiler is fired every five minutes. There are
two firemen for the battery of twelve and one for each of the others.
A gong in each fire-room is operated by electricity in connection with
a clock. The duty of the fireman is this, that when the gong strikes he
commences at one end of his fire-room and fires as rapidly as possible,
opening one-half of each furnace door. The coal is thrown only on
one-half of the grate space as he rapidly fires each boiler, the
other half is covered at the next sounding of the gong. The old style
of straight grate is used. The fires are kept six inches thick or a
little thicker. No slicing is done. It is, of course, to be understood
that the firemen arrange the quantity of coal fired according to the
apparent necessity of the case. Bituminous coal is used, and it is
broken into small pieces, so as to distribute well. Accurate account
is kept of the quantity of coal used and the engines are frequently
indicated.
TWENTY HORSE POWER.—An old engineer says the way he handled his boiler
of this size, burning 800 lbs. of screenings per day, is as follows:
My method is to run as heavy a fire as my fire-box will allow to be
kept under the bridge wall, and not to disturb it more than once in a
ten-hours run, then clean out with care and as speedily as possible,
dress light and let it come up and get ready to bank. In banking I make
sure to have an even fire, as deep as the bridge wall will allow. Then
I shut my dampers and let it lie. In the morning I open and govern by
the dampers. I do not touch my fire until 3.30 or 4 o’clock in the
afternoon, and then proceed to clean as before.
FIRING WITH COAL TAR.—The question of firing retort benches with tar
instead of coke has engaged the attention of gas managers for many
years, and various modes have been adopted for its management. The
chief difficulty has been in getting a constant flow of tar into the
furnace, uninterrupted by stoppages caused by the regulating cock or
other appliance not answering its purpose and by the carbonizing of
the tar in the delivery pipe, thus choking it up and rendering it
uncertain in action. To obviate these difficulties various plans have
been resorted to, but the best means for overcoming them are thus
described; fix the tar supply tank as near the furnace to be supplied
as convenient, and one foot higher than the tar-injector inlet. A cock
is screwed into the side of the tank, to which is attached a piece
of composition pipe 3/8-inch in diameter, ten inches long. To this a
1/2-inch iron service pipe is connected, the other end of which is
joined to the injector. By these means it is found that at the ordinary
temperature of the tar well (cold weather excepted) four gallons of
tar per hour are delivered in a constant steam into the furnace. If
more tar is required, the piece of 3/8-inch tube must be shortened,
or a larger tube substituted, and if less tar is required it must
be lengthened. The risk of stoppage in the nozzle of the injector
is overcome by the steam jet, which scatters the tar into spray and
thus keeps everything clear. Trouble being occasioned by the retorts
becoming too hot, in which case, on shutting off the flow of tar
for a while, the tar in the pipe carbonized and caused a stoppage,
a removable plug injector is fitted and ground in like the plug of
a cock, having inlets on either side for tar and steam. This plug
injector can be removed, the tar stopped in two seconds and refixed in
a similar time. The shell of the injector is firmly bolted to the top
part of the door frame. The door is swung horizontally, having a rack
in the form of a quadrant, by which it is regulated to any required
height, and to admit any quantity of air.
FIRING WITH STRAW.—The operation of burning straw under a boiler
consists in the fuel being fed into the furnace only as fast as needed.
When the straw is handled right, it makes a beautiful and very hot
flame and no smoke is seen coming from the stack. The whole secret
of getting the best results from this fuel is to feed it into the
furnace in a gradual stream as fast as consumed. When this is done
complete combustion is the result. A little hole maybe drilled in the
smoke-box door, so that the color of the fire can be seen and fire is
handled accordingly. When the smoke comes from the stack the color of
the flame is that of a good gas jet. By feeding a little faster the
color becomes darker and a little smoke comes from the stack; feeding a
little faster the flame gets quite dark and the smoke blacker; faster
still, the flame is extinguished, clouds of black smoke come from the
stack, and the pressure is falling rapidly.
FIRING WITH OIL.—Great interest is now manifested in the use of oil as
fuel. There are various devices used for this purpose, most of them
depending upon a steam jet to atomize the oil, or a system of retorts
to first heat the oil and convert it into gas, before being burned.
Another method in successful operation is the use of compressed air
for atomizing the oil—air being the element nature provides for the
complete combustion of all matter. The cleanliness of the latter system
and its comparative freedom from any odor of oil or gas and its perfect
combustion, all recommend it. Among the advantages claimed for the use
of oil over coal are 1, uniform heat; 2, constant pressure of steam;
3, no ashes, clinkers, soot or smoke, and consequently clean flues; 4,
uniform distribution of heat and therefore less strain upon the plates.
FIRING ON AN OCEAN STEAMER like the “_Umbria_.”—The men come on in
gangs of eighteen stokers or firemen and twelve coal passers, and
the “watch” lasts four hours. The “_Umbria_” has 72 furnaces, which
require nearly 350 tons of coal a day, at a cost of almost $20,000 per
voyage. One hundred and four men are employed to man the furnaces, and
they have enough to do. They include the chief engineer, his three
assistants, and ninety stokers and coal passers.
The stoker comes to work wearing only a thin undershirt, light trousers
and wooden shoes. On the “_Umbria_” each stoker tends four furnaces.
He first rakes open the furnaces, tosses in the coal, and then cleans
the fire; that is, pries the coal apart with a heavy iron bar, in order
that the fire may burn freely. He rushes from one furnace to another,
spending perhaps two or three minutes at each. Then he dashes to the
air pipe, takes his turn at cooling off, and waits for another call
to his furnace, which comes speedily. When the “watch” is over, the
men schuffle off, dripping with sweat from head to foot, through long,
cold galleries to the forecastle, where they turn in for eight hours.
Four hours of scorching and eight hours sleep make up the routine of a
fireman’s life on a voyage.
The temperature is ordinarily 120°, but sometimes reaches 160°; and the
work is then terribly hard. The space between the furnaces is so narrow
that when the men throw in coal they must take care when they swing
back their shovels, lest they throw their arms on the furnace back of
them.
In a recent trial of a government steamer the men worked willingly
in a temperature of 175°, which, however, rose to 212° or the heat
of boiling water. The shifts of four hours were reduced to 2 hours
each, but after sixteen men had been prostrated, the whole force of
thirty-six men refused to submit to the heat any longer and the trial
was abandoned.
There is no place on ocean or land where more suffering is inflicted
and endured by human beings than in these h——holes, quite properly so
called; it is to be hoped that the efforts towards reform in the matter
will not cease until completely successful.
FIRING OF SAWDUST AND SHAVINGS.—“The air was forced into the furnace
with the planer shavings at a velocity of about 12 feet per second, and
at an average temperature of about 60 degrees Fahrenheit. The shavings
were forced through a pipe 12 inches in diameter, above grate, into the
combustion chamber. The pipe had a blast gate to regulate the air in
order to maintain a pressure in the furnace, which a little more than
balanced the ascending gases in the funnel or chimney. All the fireman
had to do was to keep the furnace doors closed and watch the water in
the gauges of his boiler. The combustion in the furnace was complete,
as no smoke was visible. The shavings were forced into the combustion
chamber in a spray-like manner, and were caught into a blaze the moment
they entered. The oxygen of the air so forced into the furnace along
with the shavings gave full support to the combustion. The amount of
shavings consumed by being thus forced into the furnace was about fifty
per cent. less than the amount consumed when the fireman had to throw
them in with his shovel.”
[Illustration: Fig. 9.]
It is an important “point” when burning shavings or sawdust with a
blast, to keep the blower going without cessation, as there have been
disastrous accidents caused by the flames going up the shutes, thence
through the small dust tubes leading from the bin to the various
machines.
[Illustration: Fig. 10.]
In firing “shavings” by hand it is necessary to burn them from the top
as otherwise the fire and heat are only produced when all the shavings
are charred. To do this, provide a half-inch gas pipe, to be used as a
light poker; light the shaving fire, and when nearly burned take the
half-inch pipe and divide the burning shavings through the middle,
banking them against the side-walls, as shown in Fig. 9. Now feed a
pile of new shavings into the centre on the clean grate bars, as shown
in Fig. 10, and close the furnace doors. The shavings will begin to
burn from above, lighted from the two side fires, the air will pass
through the bars into the shavings, where it will be heated and unite
with the gas, making the combustion perfect, generating heat, and no
smoke, and the fire will last much longer and require not half the
labor in stoking.
FIRING A LOCOMOTIVE.
[Illustration]
This figure exhibits the interior of the furnace of a locomotive
engine, which varies greatly from the furnace of either a land or
marine boiler. This difference is largely caused by the method of
applying the draught for the air supply; in the locomotive this is
effected by conducting the exhaust steam through pipes from the
cylinders to the smoke-box and allowing it to escape up the smoke
stack from apertures called exhaust nozzles; the velocity of the steam
produces a vacuum, by which the products of combustion are drawn into
the smoke-box with great power and forced out of the smoke stack into
the open air.
To prevent the too quick passage of the gases into the flues an
appliance called a fire brick arch has been adopted and has proved very
efficient. In order to be self supporting it is built in the form of
an arch, supported by the two sides of the fire box which serve for
abutments. The arch has been sometimes replaced by a hollow riveted
arrangement called a water table designed to increase the fire surface
of the boiler.
FIRING A LOCOMOTIVE.—No rules can possibly be given for firing a
locomotive which would not be more misleading than helpful. This is
owing to the great variations which exist in the circumstances of the
use of the machine, as well as the differences which exist in the
various types of the locomotive.
These variations may be alluded to, but not wholly described. 1. They
consist of the sorts of fuel used in different sections of the country
and frequently on different ends of the same railroad; hard coal, soft
coal, and wood all require different management in the furnace. 2. The
speed and weight of the train, the varying number of cars and frequency
of stopping places, all influence the duties of the fireman and tax
his skill. 3. The temperature of the air, whether cold or warm, dry
weather or rain, and night time and day time each taxes the skill of
the fireman.
Hence, to be an experienced fireman in one section of the country and
under certain circumstances does not warrant the assurance of success
under other conditions and in another location. The subject requires
constant study and operation among not only “new men” but those longest
in the service.
More than in any other case to be recalled, must the fireman of a
locomotive depend upon the personal instruction of the engineer in
charge of the locomotive.
FIRING WITH TAN BARK.—Tan bark can be burned upon common grates and
in the ordinary furnace by a mixture of bituminous screenings. One
shovel full of screenings to four or five of bark will produce a more
economical result than the tan bark separate, as the coal gives body
to the fire and forms a hot clinker bed upon which the bark may rest
without falling through the spaces in the grate bars, and with the
coal, more air can be introduced to the furnace.
The above relates to common furnaces, but special fire boxes have
been recently put into operation, fed by power appliances, which work
admirably. The “point” principally to be noted as to the efficacy of
tan bark as a fuel, is to the effect, that like peat, the drier it is
the more valuable is it as a fuel.
POINTS RELATING TO FIRING.
THE PROCESS OF BOILING. Let it be remembered that the boiling spoken
of so often is really caused by the formation of the steam particles,
and that without the boiling there can be but a very slight quantity of
steam produced.
While pure water boils at 212°, if it is saturated with common salt,
it boils only on attaining 224°, alum boils at 220°, sal ammoniac at
236°, acetate of soda at 256°, pure nitric acid boils at 248°, and pure
sulphuric acid at 620°.
ON THE FIRST APPLICATION OF HEAT to water small bubbles soon begin to
form and rise to the surface; these consist of air, which all water
contains dissolved in it. When it reaches the boiling point the bubbles
that rise in it are principally steam.
IN THE CASE OF A NEW PLANT, or where the boiler has some time been
idle it is frequently advisable to build a small fire in the base of
the chimney before starting the boiler fires. This will serve to heat
the chimney and drive out any moisture that may have collected in the
interior and will frequently prevent the disagreeable smoking that
often follows the building of a fire in the furnace.
ALWAYS BEAR IN MIND that the steam in the boilers and engines is
pressing outward on the walls that confine it in every direction; and
that the enormous forces you are handling, warn you to be careful.
When starting fires close the gauge cocks and safety valve as soon as
steam begins to form.
GO SLOW. It is necessary to start all new boilers very slowly. The
change from hot to cold is an immense one in its effects on the
contraction and expansion of the boiler, the change of dimension
by expansion is a force of the greatest magnitude and cannot be
over-estimated. Leaks which start in boilers that were well made and
perfectly tight can be attributed to this cause. Something must give
if fires are driven on the start, and this entails trouble and expense
that there is no occasion for. This custom applies to engines and steam
pipes as well as to boilers. No one of any experience will open a stop
valve and let a full head of live steam into a cold line of pipe or a
cold engine.
To preserve the grate bars from excessive heat, when first firing a
boiler, it is well to sprinkle a thin layer of coal upon the grates
before putting in the shavings and wood for starting the fire. This
practice tends greatly to prolong the life of the grate-bars.
The fuel should generally be dry when used. Hard coal, however, may be
dampened a little to good advantage, as it is then less liable to crowd
and will burn more freely.
Air, high temperature and sufficient time are the principal points in
firing a steam boiler.
In first firing up make sure that the throttle valve is closed, in
order that the steam first formed may not pass over into the engine
cylinder and fill it with water of condensation. If the throttle valve
leak steam it should be repaired at the first opportunity.
Keep all heating surfaces free from soot and ashes.
Radiant rays go in all directions, yet they act in the most efficient
manner when striking a surface exactly at a right angle to their
line of movement. The sides of a fire-box are for that reason not
as efficient as the surface over the fire, and a flat surface over
the fire is the best that can be had, so far as that fact alone is
concerned.
When combustion is completed in a furnace, then the balance of the
boiler beyond the bridge wall can be utilized for taking up heat
from the gases. The most of this heat has to be absorbed by actual
contact; thus by the tubes the gases are finally divided, allowing that
necessary contact.
Combustion should be completed on the grates for the reason that
it can be effected there at the highest temperature. When this is
accomplished, the fullest benefit is had from radiant heat striking the
bottom of the boiler—_it is just there that the bulk of the work is
done_.
There must necessarily be some waste of heat by its passing up the
chimney to maintain draft. It is well to have the gases, as they enter
the chimney, as much below 600 deg. F. (down to near the temperature of
the steam) as you can and yet maintain perfect combustion.
Every steam engine has certain well-defined sounds in action which we
call noises, for want of a better term, and it is upon them and their
continuance that an engineer depends for assurance that all is going
well.
This remark also applies to the steam boiler, which has, so to speak,
a language of its own, varying in volume from the slight whisper which
announces a leaking joint to the thunder burst which terribly follows a
destructive explosion. The hoarse note of the safety-valve is none the
less significant because common.
The dampers and doors to the furnace and ash-pit should always be
closed after the fire has been drawn, in order to keep the heat of the
boiler as long as possible.
But the damper must never be entirely closed while there is fire on the
grate, as explosions dangerous in their character might occur in the
furnace from the accumulated gases.
Flues or tubes should often be swept, as soot, in addition to its
liability to becoming charged with a corroding acid, is a non-conductor
of heat, and the short time spent in cleaning them will be repaid by
the saving of labor in keeping up steam. In an establishment where they
used but half a ton of bituminous coal per day, the time of raising
steam in the morning was fifty per cent. longer when the tubes were
unswept for one week than when they were swept three times a week.
SMOKE will not be seen _if combustion is perfect_. Good firing will
abate most of the smoke.
Coals, at the highest furnace temperature, radiate much heat, whereas
gases ignited at and beyond the bridge wall radiate comparatively
little heat—it is a law in nature for a solid body highly heated to
radiate heat to another solid body.
DRY AND CLEAN is the condition in which the boiler should be kept,
_i.e._, dry outside and clean both inside and out.
To haul his furnace fire and open the safety valve before seeking his
own safety or the preservation of property, is the duty of the fireman
in the event of fire threatening to burn a whole establishment.
Many, now prominent, engineers have made their first reputation by
remembering to do this at a critical time.
WHEN WATER IS PUMPED into the boiler or allowed to run in, some opening
must be given for the escape of the contained air; usually the most
convenient way is to open the upper gauge cock after the fire has been
lighted until cloudy steam begins to escape.
In a summary of experiments made in England, it is stated that:—
“A moderately thick and hot fire with rapid draft uniformly gave the
best results.
“Combustion of black smoke by additional air was a loss.
“In all experiments the highest result was always obtained when all the
air was introduced through the fire bars.
“Difference in mode of firing only may produce a difference of 13 per
cent. (in economy).”
The thickness of the fire under the boiler should be in accordance with
the quality and size of the fuel. For hard coal the fire should be as
thin as possible, from three to six inches deep; when soft coal is
used, the fire should be thicker, from five to eight inches deep.
If it is required to burn coal dust without any change of grates,
wetting the coal is of advantage; not that it increases its heat power,
but because it keeps it from falling through the grates or going up the
chimneys. The same is true of burning shavings; by watering they are
held in the furnace, and the firing is done more easily and with better
results.
STIRRING THE FIRE should be avoided as much as possible; firing should
be performed evenly and regularly, a little at a time, as it causes
waste fuel to disturb the combustion and by making the fuel fall
through the grates into the ash pit; hence do not “clean” fires oftener
than absolutely necessary.
The slower the velocity of the gases before they pass the damper, the
more nearly can they be brought down to the temperature of the steam,
hence with a high chimney and strong draft the dampers should be kept
nearly closed, if the boiler capacity will permit it.
No arbitrary rule can be laid down for keeping fires thick or thin.
Under some conditions a thin fire is the best, under others a thick
fire gives best economy. This rule, however, governs either case: you
must have so active a fire as to give strong radiant heat.
One of the highest aims of an expert fireman should be to keep the
largest possible portion of his grate area in a condition to give great
radiant heat the largest possible part of the day—using anthracite coal
by firing light, quick and often, not covering all of the incandescent
coals. Using bituminous coal, hand firing, by coking it _very near_ the
dead plate, allowing some air to go through openings in the door, and
by pushing toward the bridge wall only live coals—when slicing, to open
the door only far enough to work the bar; this is done with great skill
in some cases.
REGULATING THE DRAFT.—This should be done so as to admit _the exact
quantity of air_ into the furnace, neither too much nor too little.
It should be remembered that fuel cannot be burned without air and if
too much air is admitted it cools the furnace and checks combustion.
It is a good plan to decrease the draft when firing or cleaning out,
by partly closing the damper or shutting off the air usually admitted
from below the grates; this is to have just draft enough to prevent the
flame from rushing out when the door is opened.
_By luminous flame_ is generally meant that which burns with a bright
yellow to white color. All flame under a boiler is not luminous,
sometimes the whole or a part of it will be red or blue. The more
luminous the flame, that is to say, the nearer white it is, the better
combustion.
TO DETERMINE THE TEMPERATURE OF A FURNACE FIRE the following table is
of use. The colors are to be observed and the corresponding degrees of
heat will be approximately as follows:
Faint red 960° F.
Bright red 1,300° F.
Cherry red 1,600° F.
Dull orange 2,000° F.
Bright orange 2,100° F.
White heat 2,400° F.
Brilliant white heat 2,700° F.
That is to say, when the furnace is at a “white heat” the heat equals
2,400 degrees Fahrenheit, etc.
Another method of finding the furnace heat is by submitting a small
portion of a particular metal to the heat.
Tin melts at 442° F.
Lead „ „ 617° F.
Zinc „ „ 700° F. nearly.
Antimony melts at 810 to 1,150° F.
Silver melts at 1,832 to 1,873° F.
Cast Iron melts at 2,000° F. nearly.
Steel „ „ 2,500° F. „
Wrought Iron melts at 2,700° F. „
Hammered Iron melts at 2,900° F. „
FOAMING IN BOILERS.
The causes are—dirty water, trying to evaporate more water than the
size and construction of the boiler is intended for, taking the steam
too low down, insufficient steam room, imperfect construction of
boiler, too small a steam pipe and sometimes it is produced by carrying
the water line too high.
Too little attention is paid to boilers with regard to their
evaporating power. Where the boiler is large enough for the water to
circulate, and there is surface enough to give off the steam, foaming
never occurs.
As the particles of the steam have to escape to the surface of the
water in the boiler, unless that is in proportion to the amount of
steam to be generated, it will be delivered with such violence that the
water will be mixed with it, and cause foaming.
For violent ebullition a plate hung over the hole where the steam
enters the dome from the boiler, is a good thing, and prevents a rush
of water by breaking it, when the throttle is opened suddenly.
In cases of very violent foaming it is imperative to check the draft
and cover the fires.
The steam pipe may be carried through the flange six inches into the
dome—which will prevent the water from entering the pipes by following
the sides of the dome as it does.
A similar case of priming of the boilers of the U. S. Steamer Galena
was stopped by removing some of the tubes under the smoke stack and
substituting bolts.
Clean water, plenty of surface, plenty of steam room, large steam
pipes, boilers large enough to generate steam without forcing the
fires, are all that is required to prevent foaming.
A high pressure insures tranquillity at the surface, and the steam
itself being more dense it comes away in a more compact form, and the
ebullition at the surface is no greater than at a lower pressure. When
a boiler foams it is best usually to close the throttle to check the
flow, and that keeps up the pressure and lessens the sudden delivery.
Too many flues in a boiler obstruct the passage of the steam from the
lower part of the boiler on its way to the surface—this is a fault in
construction.
An engineer who had been troubled with priming, finally removed 36 of
the tubes in the centre of the boiler, so as to centralize the heating
effect of the fire, thereby increasing the rapidity of ebullition at
the centre, while reducing it at the circumference. The effect of the
change was very marked. The priming disappeared at once. The water line
became nearly constant, the extreme variation being reduced to two
inches.
A CHAPTER OF DON’TS.
_Which is another way of repeating what has already been said._
1. =_Don’t_= empty the boiler when the brick work is hot.
2. =_Don’t_= pump cold water into a hot boiler.
3. =_Don’t_= allow filth of any kind to accumulate around the boiler
or boiler room.
4. =_Don’t_= leave your shovel or any other tool out of its appointed
place when not in use.
5. =_Don’t_= fail to keep all the bright work about the boiler neat
and “shiny.”
6. =_Don’t_= forget that negligence causes great loss and danger.
7. =_Don’t_= fail to be alert and ready-minded and ready-headed about
the boiler and furnace.
8. =_Don’t_= read newspapers when on duty.
9. =_Don’t_= fire up too quickly.
10. =_Don’t_= let any water or dampness come on the outside of your
boiler.
11. =_Don’t_= let any dampness get into the boiler and pipe coverings.
12. =_Don’t_= fail to see that you have plenty of water in the boiler
in the morning.
13. =_Don’t_= fail to keep the water at the same height in the boiler
all day.
14. =_Don’t_= let any one talk to you when firing.
15. =_Don’t_= allow water to remain on the floor about the boiler.
16. =_Don’t_= fail to blow off steam once or twice per day according
as the water is more or less pure.
17. =_Don’t_= fail to close the blow-off cock, when blowing off, when
the water in the boiler has sunk to one and a half inches.
18. =_Don’t fail_=, while cleaning the boiler, to examine and clean
all cocks, valves and pipes and look to all joints and packings.
19. =_Don’t_= commence cleaning the boiler until it has had time to
cool.
20. =_Don’t_= forget daily to see that the safety-valve moves freely
and is tight.
21. =_Don’t_= fail to clean the boiler inside frequently and
carefully.
22. =_Don’t_= fail to notice that the steam gauge is in order.
23. =_Don’t_= fail to keep an eye out for leaks and have them
repaired immediately, no matter how small.
24. =_Don’t_= fail to empty the boiler every week or two and re-fill
it with fresh water.
25. =_Don’t_= let any air into the furnace, except what goes through
the grate-bars, or the smoke burners, so called, by which the air is
highly heated.
26. =_Don’t_= increase the load on the safety-valve beyond the
pressure allowed by the inspector.
27. =_Don’t_= fail to open the doors of the furnace and start the
pump when the pressure is increased beyond the amount allowed, _but_
28. =_Don’t_= fail to draw the fires _when there is danger_ from the
water having fallen too low.
29. =_Don’t_= fail to check the fire—if too hot to draw, do it with
fresh coal, damp ashes, clinkers or soil; _and_
30. =_Don’t_= fail to open the doors of the furnace and close the
ash-pit doors at the time the fire is checked—_and_
31. =_Don’t_= decrease the steam pressure by feeding in water or
suddenly blowing off steam, _and_
32. =_Don’t_= touch the safety-valve, even if it be opened or closed,
_and_
33. =_Don’t_= change the feed apparatus if it is working, or the
throttle-valve be open; let them both remain as they are for a short
time, _and_
34. =_Don’t_= fail to change them very cautiously and slowly when you
close them, and
35. =_Don’t_= fail to be very cool and brave while resolute in
observing these last seven “Don’ts.”
36. =_Don’t_= fail to keep yourself neat and tidy.
37. =_Don’t_= fail to be polite as well as neat and brave.
38. =_Don’t_= fail to keep the tubes clear and free from soot and
ashes.
39. =_Don’t_= let too many ashes gather in the ash-pit.
40. =_Don’t_= disturb the fire when it is burning good nor stir it up
too often.
41. =_Don’t_= be afraid to get instruction from books and engineering
papers.
42. =_Don’t_= fail to make an honest self-examination as to points
upon which you may be ignorant, and really need to know in order to
properly attend to your duties.
43. =_Don’t_= allow too much smoke to issue from the top of the
chimney if the cause lies within your power to prevent it.
44. =_Don’t_= think that after working at firing and its kindred
duties for a year or two that _the whole subject_ of engineering has
been learned.
45. =_Don’t_= forget that one of the best helps in getting forward
is the possession of a vigorous and well-balanced mind and body—this
covers temperance and kindred virtues and a willingness to acquire
and impart knowledge.
46. =_Don’t_= forget to have your steam-gauge tested at least once in
three months.
47. =_Don’t_= use a wire or metallic rod as a handle to a swab in
cleaning the glass tube of a water-gauge for the glass may suddenly
fly to pieces when in use within a short time afterwards.
48. =_Don’t_= forget that steam pumps require as much attention as a
steam engine.
49. =_Don’t_= run a steam pump piston, unless in an emergency, at a
speed exceeding 80 to 100 feet per minute.
50. =_Don’t_= do anything without a good reason for it about the
engine or boiler, but when you are obliged to do anything, do it
thoroughly and as quickly as possible.
51. =_Don’t_= forget to sprinkle a thin layer of coal on the grates
before lighting the shavings and wood in the morning. This practice
preserves the grate bars.
52. =_Don’t_= take the cap off a bearing and remove the upper brass
simply to see if things are working well; if there is any trouble it
will soon give you notice, and, besides, you never can replace the
brass in exactly its former position, so that you may find that the
bearing will heat soon afterwards, owing to your own uncalled-for
interference.
53. =_Don’t_= put sulphur on a hot bearing, unless you intend to ruin
the brasses.
54. =_Don’t_= use washed waste that has a harsh feel, as the
chemicals used in cleansing it have not been thoroughly removed.
55. =_Don’t_=, in case of an extensive fire, involving the whole
business, rush off without drawing the fires, and raising and
_propping open_ the safety valve of the boiler.
56. =_Don’t_= fail to preserve your health, for “a sound mind in a
sound body” is beyond a money valuation.
57. =_Don’t_= fail to remember that engineers and firemen are in
control of the great underlying force of modern civilization; hence,
to do nothing to lower the dignity of the profession.
58. =_Don’t_= forget that in the care and management of
the steam boiler the first thing required is an unceasing
watchfulness—_watch-care_.
59. =_Don’t_= forget that an intemperate, reckless or indifferent man
has no business in the place of trust of a steam boiler attendant.
60. =_Don’t_= allow even a day to pass without adding one or more
facts to your knowledge of engineering in some of its branches.
STEAM GENERATORS.
In the examinations held by duly appointed officers to determine the
fitness of candidates for receiving an engineer’s license the principal
stress is laid upon the applicant’s knowledge of the parts and true
proportions of the various designs of steam boilers, and his experience
in managing them.
In fact, if there were no boilers there would be no examinations, as
the laws are framed, certificates issued and steam boiler inspection
companies formed to assure the public safety in life, limb and
property, from the dangers arising from so-called mysterious boiler
explosions.
Hence an almost undue proportion of engineers’ examinations are devoted
to the steam boiler, its management and construction. But the subject
is worthy of the best and most thoughtful attention. Every year adds to
the number of steam boilers in use. With the expanding area and growth
of population, the number of steam plants are multiplied and in turn
each new steam boiler demands a careful attendant.
There is this difference between the boiler and the engine. When the
latter is delivered from the shop and set up, it does its work with an
almost unvarying uniformity, while the boiler is a constant care. It is
admitted that the engine has reached a much greater state of perfection
and does its duty with very much more reliability than the boiler.
Even when vigilant precautions are observed, from the moment a steam
boiler is constructed until it is finally destroyed there are numerous
insidious agents perpetually at work which tend to weaken it. There is
nothing from which the iron can draw sustenance to replace its losses.
The atmosphere without and the air within the boiler, the water as
it enters through the feed-pipe and containing mineral and organic
substances, steam into which the water is converted, the sediment which
is precipitated by boiling the water, the fire and the sulphurous and
other acids of the fuel, are all natural enemies of the iron; they
sap its strength, not only while the boiler is at work and undergoing
constant strain, but in the morning before fire is started, and at
noon, night, Sundays, and other holidays it is preyed upon by these and
other corroding agents.
These are the reasons which impress the true engineer with a constant
solicitude regarding the daily and even momentary action of the steam
generator.
DESCRIPTION.
The Steam Boiler in its simplest form was simply a closed vessel partly
filled with water and which was heated by a fire box, but as steam
plants are divided into two principal parts, the engine and the boiler,
so the latter is divided again into the furnace and boiler, each of
which is essential to the other. The furnace contains the fuel to be
burnt, the boiler contains the water to be evaporated.
There must be a steam space to hold the steam when generated; heating
surface to transmit the heat from the burning fuel to the water; a
chimney or other apparatus to cause a draught to the furnace and
to carry away the products of combustion; and various fittings for
supplying the boiler with water, for carrying away the steam when
formed to the engine in which it is used; for allowing steam to escape
into the open air when it forms faster than it can be used; for
ascertaining the quantity of water in the boiler, for ascertaining the
pressure of the steam, etc., all of which, together with the engine and
its appliances is called A STEAM PLANT.
The forms in which steam generators are built are numerous, but may
be divided into three classes, viz: stationary, locomotive and marine
boilers, which terms designate the uses for which they are intended;
in this work we have to deal mainly with the first-named, although a
description with illustration is given of each type or form.
AN UPRIGHT STEAM BOILER.
To illustrate the operations of a steam generator, we give the details
of an appliance, which may be compared to the letter A of the alphabet,
or the figure 1 of the numerals, so simple is it.
Fig. 11, is an elevation of boiler, fig. 12 a vertical section through
its axis, and fig. 13 a horizontal section through the furnace bars.
[Illustration: Fig. 11.]
[Illustration: Fig. 12.]
The type of steam generator here exhibited is what is known as a
vertical tubular boiler. The outside casing or shell is cylindrical
in shape, and is composed of iron or steel plates riveted together.
The top, which is likewise composed of the same plates is slightly
dome-shaped, except at the center, which is away in order to receive
the chimney _a_, which is round in shape and formed of thin wrought
iron plates. The interior is shown in vertical section in fig. 12.
It consists of a furnace chamber, _b_, which contains the fire. The
furnace is formed like the shell of the boiler of wrought iron or
steel plates by flanging and riveting. The bottom is occupied by the
grating, on which rests the incandescent fuel. The grating consists of
a number of cast-iron bars, _d_ (fig. 12), and shown in plan in fig.
13, placed so as to have interstices between them like the grate of an
ordinary fireplace. The bottom of the furnace is firmly secured to the
outside shell of the boiler in the manner shown in fig. 12. The top
covering plate _cc_, is perforated with a number of circular holes of
from one and a half to three inches diameter, according to the size of
the boiler. Into each of these holes is fixed a vertical tube made of
brass, wrought iron, or steel, shown at _fff_ (fig. 12). These tubes
pass through similar holes, at their top ends in the plate _g_, which
latter is firmly riveted to the outside shell of the boiler. The tubes
are also firmly attached to the two plates, _cc_, _g_. They serve to
convey the flame, smoke, and hot air from the fire to the smoke box,
_h_, and the chimney, _a_, and at the same time their sides provide
ample heating surface to allow the heat contained in the products of
combustion to escape into the water. The fresh fuel is thrown on the
grating when required through the fire door, A (fig. 11). The ashes,
cinders, etc., fall between the fire bars into the ash pit, B (fig.
12). The water is contained in the space between the shell of the
boiler, the furnace chamber, and the tubes. It is kept at or about the
level, _ww_ (fig. 12), the space above this part being reserved for
the steam as it rises. The heat, of course, escapes into the water,
through the sides and top plate of the furnace, and through the sides
of the tubes. The steam which, as it rises from the boiling water,
ascends into the space above _ww_, is thence led away by the steam
pipe to the engine. Unless consumed quickly enough by the engine, the
steam would accumulate too much within the boiler, and its pressure
would rise to a dangerous point. To provide against this contingency
the steam is enabled to escape when it rises above a certain pressure
through the safety-valve, which is shown in sketch on the top of the
boiler in fig. 11. The details of the construction of safety-valves
will be found fully described in another section of this work, which
is devoted exclusively to the consideration of boiler fittings. In the
same chapters will be found full descriptions of the various fittings
and accessories of boilers, such as the water and pressure gauges,
the apparatus for feeding the boiler with water, for producing the
requisite draught of air to maintain the combustion, and also the
particulars of the construction of the boilers themselves and their
furnaces.
[Illustration: Fig. 13.]
THE GROWTH OF THE STEAM BOILER.
After the first crude forms, such as that used in connection with the
Baranca and Newcomen engine, and numerous others, the steam boiler
which came into very general use was _the plain cylinder boiler_. An
illustration is given of this in figures 14 and 15.
It consists of a cylinder A, formed of iron plate with hemispherical
ends B. B. set horizontally in brick work C. The lower part of this
cylinder contains the water, the upper part the steam. The furnace D
is outside the cylinder, being beneath one end; it consists simply of
grate bars _e e_ set in the brick work at a convenient distance below
the bottom of the boiler.
[Illustration: Fig. 14.]
[Illustration: Fig. 15.]
The sides and front of the furnace are walls of brick work, which,
being continued upwards support the end of the cylinder. The fuel is
thrown on the bars through the door which is set in the front brick
work. The air enters between the grate bars from below. The portion
below the bars is called the ash pit. The flame and hot gases, when
formed, first strike on the bottom of the boiler, and are then carried
forward by the draft, to the so-called bridge wall _o_, which is a
projecting piece of brick work which contracts the area of the flue _n_
and forces all the products of combustion to keep close to the bottom
of the boiler.
Thence the gases pass along the flue _n_, and return part one side
of the cylinder in the flue _m_ (fig. 15) and back again by the other
side flue _m_ to the far end of the boiler, whence they escape up the
chimney. This latter is provided with a door or damper _p_, which can
be closed or opened at will, so as to regulate the draught.
This boiler has been in use for nearly one hundred years, but has two
great defects. The first is that the area of heating surface, that is
the parts of the boiler in contact with the flames, is too small in
proportion to the bulk of the boiler; the second is, that if the water
contains solid matter in solution, as nearly all the water does to a
greater or less extent, this matter becomes deposited on the bottom
of the boiler just where the greatest evaporation takes place. The
deposit, being a non-conductor, prevents the heat of the fuel from
reaching the water in sufficient quantities, thus rendering the heating
surface inefficient; and further, by preventing the heat from escaping
to the water, it causes the plates to become unduly heated, and quickly
burnt out.
There is another defect belonging to this system of boiler to which
many engineers attach great importance, viz.: that the temperature
in each of the three flues _n_, _m_, _m´_ is very different, and
consequently that the metal of which the shell of the boiler is
composed expands very unequally in each of the flues, and cracks
are very likely to take place when the effects of the changes of
temperature are most felt. It will be noted that the flames and gases
in this earliest type of steam boiler make three turns before reaching
the chimney, and as these boilers were made frequently as much as 40
feet long it gave the extreme length of 120 feet to the heat products.
THE CORNISH BOILER is the next form in time and excellence. This is
illustrated in figures 16 and 17.
It consists also of a cylindrical shell _A_, with flat ends as
exhibited in cuts. The furnace, however, instead of being situated
underneath the front end of the shell, is enclosed in it in a second
cylinder _B_, having usually a diameter a little greater than half that
of the boiler shell. The arrangement of the grate and bridge is evident
from the diagram. After passing the bridge wall the heat products
travel along through the internal cylinder _B_, till they reach the
back end of the boiler; then return to the front again, by the two side
flues _m_, _m_´, and thence back again to the chimney by the bottom of
flue _n_.
In this form of boiler the heating surface exceeds that of the last
described by an amount equal to the area of the internal flues, while
the internal capacity is diminished by its cubic contents; hence for
boilers of equal external dimensions, the ratio of heating surface
to mass of water to be heated, is greatly increased. Boilers of this
sort can, however, never be made of as small diameters as the plain
cylindrical sort, on account of the necessity of finding room inside,
below the water level, for the furnace and flue.
[Illustration: Fig. 16.]
[Illustration: Fig. 17.]
The disadvantage, too, of the deposits mentioned in the plain cylinder
is, to a great extent got over in the Cornish boiler, for the bottom,
where the deposit chiefly takes place, is the coolest instead of being
the hottest part of the heating surface.
But the disadvantage of unequal expansion also exists in this type
of boiler, as the internal flue in the Cornish system is the hottest
portion of the boiler, and consequently undergoes a greater lengthways
expansion than the flues. The result is to bulge out the ends, and when
the boiler is out of use, the flue returns to its regular size, and
thus has a tendency to work loose from the ends to which it is riveted
and if the ends are too rigid to move, a very serious strain comes on
the points of the flue.
Even while in use the flue of a Cornish boiler is liable to undergo
great changes in temperature, according to the state of the fire;
when this latter is very low, or when fresh fuel has been thrown on,
the temperature is a minimum and reaches a maximum again when the
fresh fuel commences to burn fiercely. This constant expansion and
contraction is found in practice to also so weaken the tube that
it frequently collapses or is pressed together, resulting in great
disaster.
This led to the production and adoption of the—
LANCASHIRE BOILER, contrived to remedy this inconvenience and also to
attain a more perfect combustion, the arrangement of the furnaces of
which is shown in fig. 19 and fig. 20.
It will be observed that there are two internal furnaces instead
of one, as in the Cornish type. These furnaces are sometimes each
continued as a separate flue to the other end of the boiler as shown
in the cuts; but as a rule they emerge into one internal flue. They
are supposed to be fired alternately, and the smoke and unburned gases
issuing from the fresh fuel are ignited in the flue by the hot air
proceeding from the other furnace, the fuel in which is in a state of
incandescence. Thus all violent changes in the temperature are avoided,
and the waste of fuel due to unburned gases is avoided, if the firing
is properly conducted.
[Illustration: LANCASHIRE BOILER—Fig. 18.]
The disadvantage of the Lancashire boiler is the difficulty of finding
adequate room for the two furnaces without unduly increasing the
diameter of the shell. Low furnaces are extremely unfavorable to
complete combustion, the comparatively cold crown plates, when they are
in contact with the water of the boiler, extinguishing the flames from
the fuel, when they are just formed, while the narrow space between
the fuel and the crown does not admit the proper quantity of air being
supplied above the fuel to complete the combustion of the gases, as
they arise.
On the other hand, though this boiler favors the formation of the
smoke, it supplies the means of completing the combustion afterwards,
as before explained, by means of the hot air from the second furnace.
[Illustration: Fig. 18 (_a_)]
Another disadvantage is the danger of collapsing the internal flue
already spoken of; this is remedied by the introduction of what are
called the galloway tubes, illustrated in the cut shown on this page,
which is a cross section of the water tubes shown in Figs. 18 and 20.
These tubes not only contribute to strengthen the flues but they add to
the heating surface and greatly promote the circulation so important in
the water space.
NOTE.
These descriptions and illustrations of the Lancashire boiler are of
general value, owing to the fact that very many exhaustive tests and
experiments upon steam economy have been made and permanently recorded
in connection with this form of steam generator.
In the GALLOWAY form of boiler the flue is sustained and stiffened by
the introduction of numerous conical tubes, flanged at the two ends and
riveted across the flue. These tubes, a sketch of which are given in
fig. 18 (_a_), are in free communication with the water of the boiler,
and besides acting as stiffeners, they also serve to increase the
heating surface and to promote circulation.
[Illustration: Figs. 19, 20.]
The illustration (figs. 18, 19 and 20) give all the principal details
of a Lancashire boiler fitted with Galloway tubes. Fig. 18 represents a
longitudinal section and figs. 19 and 20 shows on a large scale an end
view of the front of the boiler with its fittings and also a transverse
section. The arrangement of the furnaces, flues, and the Galloway tubes
is sufficiently obvious from the drawings. The usual length of these
boilers is 27 feet, though they are occasionally made as short as 21
feet.
The minimum diameter of the furnaces is 33 inches, and in order to
contain these comfortably the diameter of the boiler should not be
less than 7 feet. The ends of the boiler are flat, and are prevented
from bulging outwards by being held in place by the furnaces and flues
which stay the two ends together and also by the so-called gusset stays
_e_, _e_. In addition to the latter the flat ends of the boiler have
longitudinal rods to tie them together; one of these is shown at _A_,
_A_, fig. 18.
The steam is collected in the pipe _S_, which is perforated all along
the top so as to admit the steam and exclude the water spray which may
rise to the surface during ebullition. The steam thence passes to the
stop valve _T_ outside the boiler and thence to the steam pipes to the
engines.
There are two safety valves on top of the boiler on _B_ (fig. 18),
being of the dead weight type described hereafter, and the other, _C_,
being a so-called low water safety valve. It is attached by means of a
lever and rod to the float _F_, which ordinarily rests on the surface
of the water. When through any neglect, the water sinks below its
proper level the float sinks also, causing the valve to open, thus
allowing steam to escape and giving an alarm. _M_ is the manhole with
its covering plate, which admits of access to the interior of the
boiler and _H_ is the mud hole by which the sediment which accumulates
all along the bottom is raked out. Below the front end and underneath,
the pipe and stay valve are shown, by which the boiler can be emptied
or blown off.
On the front of the boiler (fig. 19) are shown, the pressure gauges,
the water gauges and the furnace door; _K_ is the feed pipe; _R_, _R_,
a pipe and cock for blowing off steam. In the front of the setting are
shown two iron doors by which access may be gained to the two lower
external flues for cleaning purposes.
In the Lancashire boiler it is considered advisable to take the
products of combustion, after they leave the internal flues, along the
bottom of the boiler, and then back to the chimney by the side. When
this plan is adopted the bottom is kept hotter than would otherwise be
the case, and circulation is promoted, which prevents the coldest water
from accumulating at the bottom.
The Galloway (or Lancashire) boiler is considered the most economical
boiler used in England, and is being introduced into the United States
with success. The long traverse of heat provided (three turns of about
27 feet each) contributes greatly to its efficiency.
It may be useful to add the following data relating to this approved
steam generator, being the principal dimensions and other data of the
boiler shown in fig. 18:
Steam pressure, 75 lbs. per sq. inch.
Length, 27 feet.
Diameter, 7 feet.
Weight, total, 15-1/2 tons.
Shell plates, 7/16 inch.
Furnace diameter, 33 inches.
Furnace Plates, 3/8 inch.
End plates, 1/2 inch.
Grate area, 33 sq. feet.
Heating surface:
In furnace and flues 450 sq. feet.
In Galloway pipes, 30 „
In external flues, 370 „
----
850 sq. feet.
We have thus detailed step by step the improvement of the steam boiler
to a point where it is necessary to describe at length the locomotive,
the marine, the horizontal tubular and the water tube boilers, which
four forms comprehend ninety-nine out of one hundred steam generators
in use in the civilized world at the present time.
MARINE BOILERS.
The boilers used on board steamships are of two principal types. The
older sort used for steam of comparatively low temperature, viz.: up
to 35 lbs. per square inch, is usually made of flat plates stayed
together, after the manner of the exterior and interior fire boxes of a
locomotive boiler.
Medium high pressure marine boilers, constructed for steam of 60 to
150 lbs. per square inch, are circular or oval in cross section, and
are fitted with round interior furnaces and flues like land boilers.
There are many variations of marine boilers, adapted to suit special
circumstances. Fig. 22 shows a front elevation and partial sections of
a pair of such boilers and Fig. 23 shows one of them in longitudinal
vertical section.
THE MARINE STEAM BOILER
[Illustration: Fig. 22.]
[Illustration: Fig. 23.]
It will be seen from these drawings that there are three internal
cylindrical furnaces at each end of these boilers, making in all six
furnaces per boiler. The firing takes place at both ends. The flame and
hot gases from each furnace, after passing over the bridge wall enter a
flat-sided rectangular combustion chamber and then travel through tubes
to the front uptake (_i.e._ the smoke bonnet or breaching), and so on
to the chimney.
The sides of the combustion chambers are stayed to each other and to
the shell plate of the boiler; the tops are strengthened in the same
manner as the crowns of locomotive boilers, and the flat plates of the
boiler shell are stayed together by means of long bolts, which can be
lengthened up by means of nuts at their ends. Access is gained to the
uptakes for purposes of cleaning, repairs of tubes, etc., by means of
their doors on their fronts just above the furnace doors. The steam is
collected in the large cylindrical receivers shown above each boiler.
The material of construction is mild steel.
The following are the principal dimensions and other particulars of one
of these boilers:
Length from front to back, 20 feet.
Diameter of shell, 15 feet 6 inches.
Length of furnace, 6 feet 10 inches.
Diameter of furnace, 3 feet 10 inches.
Length of tubes, 6 feet 9 inches.
Diameter of tubes, 3-1/2 inches.
No. of tubes, 516.
Thickness of shell plates, 15/16.
Thickness of tube plates, 3/4.
Grate area, 126-1/2 square feet.
Heating surface, 4015 square feet.
Steam pressure, 80 lbs. per sq. inch.
Fig. 24 is a sketch of a modern marine boiler, which is only fired
from one end, and is in consequence much shorter in proportion to its
diameter than the type illustrated in figs. 22 and 23.
Marine boilers over nine feet in diameter have generally two furnaces,
those over 13 to 14 feet, three, while the very largest boilers used
on first-class mail steamers, and which often exceed fifteen feet in
diameter, have four furnaces.
In the marine boiler the course taken by the products of combustion
is as follows; the coal enters through the furnace doors on to the
fire-bars, the heat and flames pass over the fire bridge into the flame
or combustion chamber, thence through the tubes into the smoke-box, up
the up-take and funnel into the air.
[Illustration: Fig. 24.]
The fittings to a marine boiler are—funnel and air casings, up-takes
and air casings, smoke boxes and doors, fire doors, bars, bridges,
and bearers, main steam stop valve, donkey valve, safety valves and
drain pipes, main and donkey feed check valves, blow-off and scum
cocks, water gauge glasses on front and back of boiler, test water cock
for trying density of water, steam cock for whistle, and another for
winches on deck.
A fitting, called a blast pipe, is sometimes placed in the throat of
the funnel. It consists of a wrought iron pipe, having a conical nozzle
within the funnel pointing upwards, the other end being connected to
a cock, which latter is bolted on to the steam space or dome of the
boiler. It is used for increasing the intensity of the draft, the
upward current of steam forcing the air out of the funnel at a great
velocity; and the air having to be replaced by a fresh supply through
the ash-pits and bars of the furnaces, a greater speed of combustion is
obtained than would otherwise be due to simple draft alone.
Boilers are fitted with dry and wet uptakes, which differ from each
other as follows:—The dry uptake is wholly outside the boiler, and
consists of an external casing bolted on to the firing end of the
boiler, covering the tubes and forming the smoke-box, and is fitted
with suitable tube doors. A wet uptake is carried back from the firing
ends of the boiler into its steam space, and is wholly surrounded
by water and steam. The dry uptake seldom requires serious repair;
but the wet uptake, owing to its exposure to pressure, steam, and
water, requires constant attention and repair, and is very liable to
corrosion, being constantly wetted and dried in the neighborhood of the
water-line. The narrow water space between both front uptakes is also
very liable to become burnt, owing to accumulation of salt. The flue
boilers of many tugs and ferry boats are fitted with wet uptakes.
A superheater is a vessel usually placed in the uptake, or at the base
of the funnel of a marine boiler, and so arranged that the waste heat
from the furnaces shall pass around and through it prior to escaping up
the chimney. It is used for drying or heating the steam from the main
boiler before it enters the steam pipes to the engine. The simplest
form of superheater consists of a wrought iron drum filled with tubes.
The heat or flame passes through the tubes and around the shell of
the drum, the steam being inside the drum. Superheaters are usually
fitted with a stop valve in connection with the boiler, by means of
which it can be shut off; and also one to the steam pipe of the engine;
arrangements are also usually made for mixing the steam or working
independently of the superheater.
A safety-valve is also fitted and a gauge glass; the latter is to show
whether the superheater is clear of water, as priming will sometimes
fill it up.
The special fittings of the marine boiler will be more particularly
described hereafter as well as the stays, riveting, strength, etc.,
etc.
The use of the surface condenser in connection with the marine boiler
was an immense step toward increasing its efficiency. In 1840 the
average pressure used in marine boilers was only 7 or 8 lbs. to the
square inch, the steam being made with the two-flue pattern of boiler,
sea water being used for feed; as the steam pressure increased as now
to 150 to 200 lbs. to the square inch, greater and greater difficulty
was experienced from salt incrustation—in many cases the tubes did not
last long and frequently gave much trouble, until the introduction of
the surface condenser, which supplied fresh water to the boilers.
[Illustration: Fig. 25]
THE SURFACE CONDENSER.
The condenser is an oblong or circular box of cast iron fitted in one
of two ways, either with the tubes horizontal or vertical; at each end
are fixed the tube plates, generally made of brass, and the tubes pass
through the plates as well as through a supporting plate in the middle
of the condenser. Each end of the condenser is fitted with doors for
the purpose of enabling the tube ends to be examined, drawn, or packed,
as may be necessary. The tube ends are packed in various ways, and the
tubes are made of brass, so as to resist the action of the water. The
water is generally sucked through the tubes by the circulating pump,
and the steam is condensed by coming in contact with the external
surface of the tubes. In some cases the water is applied to the
external surface, and the steam exhausted through the tubes; but this
practice is now generally given up in modern surface condensers. The
packing round the tube ends keeps them quite tight, and in the event
of a split tube, a wooden plug is put in each end until an opportunity
offers for drawing it and replacing with a new one.
The condenser may be made of any convenient shape. It sometimes forms
part of the casting supporting the cylinders of vertical engines; it
is also frequently made cylindrical with flat ends, as in fig. 25. The
ends form the tube plates to which the tubes are secured. The tubes
are, of course, open at the ends, and a space is left between the tube
plate and the outer covers, shown at each end of the condenser, to
allow of the circulation of water as shown by the arrows.
OPERATION OF THE CONDENSER.
The cold water, which is forced through by a circulating pump, enters
at the bottom, and is compelled to pass forward through the lower set
of tubes by a horizontal dividing plate; it then returns through the
upper rows of tubes and passes out at the overflow; the tubes are thus
maintained at a low temperature.
The tubes are made to pass right through the condensing chamber, and so
as to have no connection with its internal space. The steam is passed
into the condenser and there comes in contact with the cold external
surface of the tube, and is condensed, and removed as before, by the
air pump, as may be readily seen in the illustration (p. 65.)
The advantages gained by the use of the surface condenser are: 1. The
feed water is hotter and fresh; being hotter, it saves the fuel that
would be used to bring it up to this heat; and being fresh it boils at
a lower temperature. 2. Not forming so much scale inside the boiler,
the heat passes through to the water more readily; and as the scum cock
is not used so freely, all the heat that would have been blown off is
saved. Its disadvantages are that being fresh water and forming no
scale on the boiler, it causes the boiler to rust.
It is often said that one engineer will get more out of a ship than
another. In general it will be found that the most successful engineer
is the man who manages his stokers best. It is very difficult on
paper to define what is meant. It is a thing to be felt or seen, not
described. * * * * The engineer who really knows his business will give
his fires a fair chance to get away. He will work his engines up by
degrees and run a little slowly for the first few moments.
WATER TUBE STEAM BOILERS.
[Illustration: WATER TUBE BOILER.—Fig. 26.]
A popular form of steam boiler in use in the United States and Europe
is what is called the water tube boiler. This term is applied to a
class of boiler in which the water is contained in a series of tubes,
of comparatively small diameter, which communicate with each other and
with a common steam-chamber. The flames and hot gases circulate between
the tubes and are usually guided by partitions so as to act equally on
all portions of the tubes. There are many varieties of this type of
boiler of which the cut illustrates one: in this each tube is secured
at either end into a square cast-iron head, and each of these heads
has two openings, one communicating with the tube below and the other
with the tube above; the communication is effected by means of hollow
cast-iron caps shown at the end of the tubes; the caps have openings in
them corresponding with the openings in the tube heads to which they
are bolted.
In the best forms of the water tube boilers, it is suspended entirely
independent of the brick work from wrought iron girders resting on iron
columns. This avoids any straining of the boiler from unequal expansion
between it and its enclosing walls and permits the brick work to be
repaired or removed, if necessary, without in any way disturbing the
boiler. This design is shown in Fig. 26.
The distinguishing difference, which marks the water tube boiler
from others, consists in the fact that in the former the small tubes
are filled with water instead of the products of combustions; hence
the comparison, frequently made, between water-tube and _fire tube_
boilers—the difference has been expressed in another way, “Water-tube
vs. shell boilers,” but the principle of steam production in both
systems remains the same; the heat from the combustible is transferred
to the water through the medium of iron plates and in both, the
furnaces, steam appliances, application of the draught, etc., is
substantially the same. In another important point do the systems
agree, _i.e._, in the average number of pounds of water evaporated
per lb. of combustible; it is in the thoroughness of construction
and skillfulness of adaptation to surroundings that produce the best
results. Water tube or sectional boilers, have been made since the
days of James Watt, in 1766, in many different forms and under various
names. Owing, however, to the imperfection of manufacture the system,
as compared to shell boilers, has been a failure until very recently;
various patterns of water-tube boilers are now in most favorable
and satisfactory use. The advantages claimed for this form of steam
generator are as follows:
1. Safety from disastrous explosions, arising from the division of
the contents into small portions, and especially from details of
construction which make it tolerably certain that the rupture will be
local instead of a general violent explosion which liberates at once
large masses of steam and water.
2. The small diameter of the tubes of which they are composed render
them much stronger than ordinary boilers.
3. They can be cheaply built and easily repaired, as duplicate pieces
can be kept on hand. The various parts of a boiler can be transported
without great expense, trouble or delay; the form and proportions of a
boiler can be suited to any available space; and, again, the power can
be increased by simply adding more rows of tubes and increasing the
grate area.
4. Their evaporative efficiency can be made equal to that of other
boilers, and, in fact, for equal proportions of heating and grate
surfaces, it is often a trifle higher.
5. Thin heating surface in the furnace, avoiding the thick plates
necessarily used in ordinary boilers which not only hinder the
transmission of heat to the water, but admit of overheating.
6. Joints removed from the fire. The use of lap welded water tubes with
their joints removed from the fire also avoid the unequal expansion of
riveted joints consequent upon their double thickness.
7. Quick steaming.
8. Accessibility for cleaning.
9. Ease of handling and erecting.
10. Economy and speediness of repairs.
The known disadvantages of these boilers are
1. They generally occupy more space and require more masonry than
ordinary boilers.
2. On account of the small quantity of water which they contain, sudden
fluctuations of pressure are caused by any irregularities in supplying
the feed-water or in handling the fires, and the rapid and at times
violent generation of steam causes it to accumulate in the contracted
water-chambers, and leads to priming, with a consequent loss of water,
and to overheated tubes.
3. The horizontal or inclined water tubes which mainly compose these
boilers, do not afford a ready outlet for the steam generated in
them. The steam bubbles cannot follow their natural tendency and rise
directly, but are generally obliged by friction to traverse the tube
slowly, and at times the accumulation of steam at the heated surfaces
causes the tubes to be split or burned.
4. The use of water which forms deposits of solid matter still further
increases the liability to overheating of the tubes. It has been
claimed by some inventors that the rapid circulation of the water
through the tubes would prevent any deposit of scale or sediment in
them, but experience has proved this to be a grave error. Others have
said that the expansion of the tube would detach the scale as fast
as it was deposited and prevent any dangerous accumulation, but this
also has been proved an error. Again, the use of cast iron about these
boilers has frequently been a constant source of trouble from cracks,
etc.
CARE OF WATER TUBE BOILERS.
The soot and ashes collect on _the exterior_ of the tubes in this form
of boilers, instead of inside the tubes, as in the tubular, and they
must be as carefully removed in one case as in the other; this can be
done by the use of blowing pipe and hose through openings left in the
brick work; in using bituminous coal the soot should be brushed off
when steam is down.
All the inside and outside surfaces should be kept clean to avoid waste
of fuel; to aid in this service the best forms are provided with extra
facilities for cleaning. For inspection, remove the hand holes at both
ends of the tubes, and by holding a lamp at one end and looking in at
the other the condition of the surface can be freely seen. Push the
scraper through the tube to remove sediment, or if the scale is hard,
use the chipping scraper made for that purpose.
Hand holes should be frequently removed and surfaces examined,
particularly in case of a new boiler. In replacing hand hole caps,
clean the surfaces without scratching or bruising, smear with oil and
screw up tight.
The mud drum should be periodically examined and the sediment removed;
blow-off cocks and check valves should be examined each time the boiler
is cleaned; when surface blow-cocks are used they should be often
opened for a few minutes at a time; be sure that all openings for air
to boiler or flues _except through the fire_, are carefully stopped.
If a boiler is not required for some time, empty and dry it thoroughly.
If this is impracticable, fill it quite full of water and put in a
quantity of washing soda; and external parts exposed to dampness should
receive a coating of linseed oil. Avoid all dampness in seatings or
coverings and see that no water comes in contact with the boiler from
any cause.
Although this form of boiler is not liable to destructive explosion,
the same care should be exercised to avoid possible damage to boilers
and expensive delays.
SECTIONAL BOILERS.
Probably one of the first sectional boilers brought into practical use
is one made of hollow cast iron spheres, each 8 inches in diameter,
externally, and 3/8 of an inch thick, connected by curved necks 3-1/2
inches in diameter. These spheres are held together by wrought iron
bolts and caps, and in one direction are cast in sets of 2 or 4, which
are afterwards drawn together so as to give more or less heating
surface to the boiler according to the number used.
NOTE.
Owing to their multiplication of parts all sectional, including water
tube boilers, should be made with unusual care in their details of
construction, setting, fittings and proportions. It is to the attention
paid to these “points” that the sectional boilers are now coming into
more general favor.
LOCOMOTIVE BOILERS.
The essential features of locomotive boilers are dictated by the duties
which they have to perform under peculiar conditions. The size and the
weight are limited by the fact that the boiler has to be transported
rapidly from place to place, and also that it has to fit in between
the frames of the locomotive; while at the same time, the pressure of
the steam has to be very great in order that with comparatively small
cylinder the engine may develop great power; moreover, the quantity of
water which has to be evaporated in a given time is very considerable.
To fulfil these latter conditions a large quantity of coal must be
burned on a fire grate of limited area; hence intense combustion is
necessary under a forced blast. To utilize advantageously the heat
thus generated, a large heating surface must be provided and this can
only be obtained by passing the products of combustion through a great
number of tubes of small diameter.
The forced draught in a locomotive boiler is obtained by causing the
steam from the cylinders, after it has done its work, to be discharged
into the chimney by means of a pipe called the blast pipe; the lower
portion of this consists of two branches, one in communication with the
exhaust port of each cylinder. As each puff of steam from the blast
pipe escapes up the chimney it forces the air out in front of it,
causing a partial vacuum, which can only be supplied by the air rushing
through the furnace and tubes.
The greater the body of steam escaping at each puff, and the more
rapid the succession of puffs, the more violent is the action of the
blast pipe in producing a draught, and consequently this contrivance
regulates the consumption of fuel and the evaporation of water to a
certain extent automatically, because when the engine is working its
hardest and using the most steam, the blast is at the same time most
efficacious.
[Illustration: LOCOMOTIVE BOILER.—Fig. 27.]
The blast pipe is perhaps, the most distinctive feature of the
locomotive boiler, and the one which has alone rendered it possible to
obtain large quantities of steam from so small a generator. The steam
blast of a locomotive has been compared to the breathing apparatus of a
man, and has rendered the mechanism described nearer a live thing than
any other device man has ever produced.
On account of the oscillations, or violent motions to which the boiler
of locomotive engines are subject, weighted safety-valves are not
possible to be used and springs are used instead to hold the valves in
place.
The locomotive form of steam boiler is sometimes used for stationary
engines, but owing to extra cost and increased liability to corrode in
the smaller passage they are not favorites.
DESCRIPTION OF PAGE ILLUSTRATION.
In fig. 27, F B represents the fire box or furnace; F D, fire door;
D P, deflector plate; F T P, fire box tube plate; F B R S, fire box
roof stays; S T P, smoke box tube plate; S B, smoke box; S B D,
smoke box door; S D, steam dome; O S, outer shell; R S V, Ramsbottom
safety-valve; F, funnel or chimney.
[Illustration: Fig. 28.]
The crown plate of the fire-box being flat requires to be efficiently
stayed, and for this purpose girder stays called fox roof stays are
mostly used, as shown in the figure. The stays are now made of cast
steel for locomotives. They rest at the two ends on the vertical plates
of the fire-box, and sustain the pressure on the fire-box crown by a
series of bolts passing through the plate and girder stay, secured by
nuts and washers. Fig. 28 is a plan and elevation of a wrought-iron
roof stay.
Another method adopted in locomotive types of marine boilers for
staying the flat crown of the fire-box to the circular upper plate is
shown in fig. 29—namely, by wrought-iron vertical bar stays secured by
nuts and washers to the fire-box with a fork end and pin to angle-iron
pieces riveted to the boiler shell.
[Illustration: Fig. 29.]
The letters in this figure refer to the same parts of the boiler as do
those in fig. 27, _i.e._, F B to the fire-box, etc., etc.
It was formerly the custom to make the tubes much longer than shown
in the fig., with the object of gaining heating surface; but modern
experience has shown that the last three or four feet next the smoke
box were of little or no use, because, by the time the products of
combustion reached this part of the heating surface, their temperature
was so reduced that but little additional heat could be abstracted from
them. The tubes, in addition to acting as flues and heating surface,
fulfil also the function of stays to the flat end of the barrel of the
boiler, and the portion of the fire box opposite to it.
In addition to the staying power derived from the tubes, the smoke box,
tube plate and the front shell plate are stayed together by several
long rods.
[Illustration: THE HORIZONTAL TUBULAR BOILER.—Fig. 30.]
STANDARD HORIZONTAL TUBULAR STEAM BOILER.
TABLE OF SIZES, PROPORTIONS, ETC.:
========+========+=======+=======+======+========+=========+========+=======
Diameter| Length |Gauge | Gauge |Number|Diameter| Length |Square |Nominal
of | of | of | of | of | of | of |feet of | Horse
Shell. | Shell. |Shell. | Heads.|Tubes.| Tubes. | Tubes. |Heating | Power.
| | | | | | |Surface.|
--------+--------+-------+-------+------+--------+---------+--------+-------
72 in.|19ft.4in|3/8 in.| 1/2in.| 80 |4 in.|18ft.0in.| 1,500 | 100
72 „ |18 „ 4 „|3/8 „ | 1/2 „ | 86 |3-1/2 „ |17 „ 0 „ | 1,500 | 100
72 „ |17 „ 4 „|3/8 „ | 1/2 „ | 108 |3 „ |16 „ 0 „ | 1,500 | 100
--------+--------+-------+-------+------+--------+---------+--------+-------
66 „ |18 „ 4 „|3/8 „ | 1/2 „ | 74 |3-1/2 „ |17 „ 0 „ | 1,350 | 90
66 „ |17 „ 4 „|3/8 „ | 1/2 „ | 92 |3 „ |16 „ 0 „ | 1,350 | 90
--------+--------+-------+-------+------+--------+---------+--------+-------
60 „ |18 „ 3 „|3/8 „ | 1/2 „ | 78 |3 „ |17 „ 0 „ | 1,200 | 80
60 „ |17 „ 3 „|3/8 „ | 1/2 „ | 76 |3 „ |16 „ 0 „ | 1,125 | 75
60 „ |16 „ 3 „|3/8 „ | 1/2 „ | 77 |3 „ |15 „ 0 „ | 1,050 | 70
60 „ |16 „ 3 „|3/8 „ | 1/2 „ | 70 |3 „ |15 „ 0 „ | 975 | 65
60 „ |16 „ 3 „|3/8 „ | 1/2 „ | 64 |3 „ |15 „ 0 „ | 900 | 60
--------+--------+-------+-------+------+--------+---------+--------+-------
54 „ |17 „ 3 „|5/16 „ |7/16 „ | 60 |3 „ |16 „ 0 „ | 900 | 50
54 „ |17 „ 3 „|5/16 „ |7/16 „ | 56 |3 „ |16 „ 0 „ | 825 | 55
54 „ |16 „ 3 „|5/16 „ |7/16 „ | 52 |3 „ |15 „ 0 „ | 750 | 50
54 „ |16 „ 3 „|5/16 „ |7/16 „ | 46 |3 „ |15 „ 0 „ | 675 | 45
54 „ |16 „ 3 „|5/16 „ |7/16 „ | 40 |3 „ |15 „ 0 „ | 600 | 40
--------+--------+-------+-------+------+--------+---------+--------+-------
48 „ |17 „ 2 „|5/16 „ |7/16 „ | 50 |3 „ |16 „ 0 „ | 750 | 50
48 „ |16 „ 2 „|5/16 „ |7/16 „ | 48 |3 „ |15 „ 0 „ | 675 | 45
48 „ |16 „ 2 „|5/16 „ |7/16 „ | 42 |3 „ |15 „ 0 „ | 600 | 40
--------+--------+-------+-------+------+--------+---------+--------+-------
42 „ |16 „ 2 „|1/4 „ | 3/8 „ | 36 |3 „ |15 „ 0 „ | 525 | 85
42 „ |15 „ 2 „|1/4 „ | 3/8 „ | 32 |3 „ |14 „ 0 „ | 450 | 30
42 „ |14 „ 2 „|1/4 „ | 3/8 „ | 28 |3 „ |13 „ 0 „ | 375 | 25
--------+--------+-------+-------+------+--------+---------+--------+-------
36 „ |14 „ 2 „|1/4 „ | 3/8 „ | 36 |2-1/2 „ |13 „ 0 „ | 375 | 25
36 „ |14 „ 2 „|1/4 „ | 3/8 „ | 28 |2-1/2 „ |13 „ 0 „ | 300 | 20
36 „ |13 „ 2 „|1/4 „ | 3/8 „ | 20 |2-1/2 „ |12 „ 0 „ | 225 | 15
36 „ |12 „ 2 „|1/4 „ | 3/8 „ | 14 |2-1/2 „ |11 „ 0 „ | 150 | 10
========+========+=======+=======+======+========+=========+========+=======
NOTE.
In estimating the horse power by means of the above table, 15 square
feet has been allowed for each horse power, and the number of feet in
each boiler is given _in round numbers_. This table is one used in
every-day practice by boiler makers.
THE FLUE BOILER.
[Illustration: THE TWO FLUE BOILER.—Fig. 31.]
[Illustration: THE SIX INCH FLUE BOILER.—Fig. 32.]
THE HORIZONTAL TUBULAR STEAM BOILER.
The great majority of stationary boilers are cylindrical or round
shaped, because—
1. The cylindrical form is the strongest.
2. It is the cheapest.
3. It permits the use of thinner metal.
4. It is the safest.
5. It is inspected without difficulty.
6. It is most symmetrical.
7. It is manufactured easier.
8. It resists internal strain better.
9. It resists external strain also.
10. It can be stayed or strengthened better.
11. It encloses the greatest volume with least material.
12. It is the result of many years’ experience in boiler practice.
13. It is the form adopted or preferred by all experienced engineers.
It follows, too, that _the horizontal tubular boiler_, substantially
as shown in fig. 30, is the standard steam boiler; engineers and steam
power owners cling with great tenacity to this approved form, which is
an outgrowth of one hundred years’ experience in steam production.
In the plain horizontal tubular boiler shown in cuts, the shell is
filled with as many small tubes varying from two inches to four inches
in diameter as is consistent with the circulation and steam space. In
firing this type of boiler the combustion first takes place under the
shell, and the products, such as heat, flame, and gas, pass through
the small tubes to the chimney, although in the triple draught pattern
of the tubular boiler, the heat products pass, as will hereafter be
explained, a second time through the boiler tubes, making three turns
before the final loss of the extra heat takes place.
The illustrations on pages 78 and 80 exhibit the gradual advances to
the horizontal tubular by the two-flued boiler (fig. 31) of the six
flues (fig. 32) and of the locomotive Portable Boiler (fig. 33). The
vertical or upright tubular boiler is but another modification of the
horizontal tubular.
[Illustration: THE LOCOMOTIVE PORTABLE BOILER.—Fig. 33.]
In parts of the vertical boiler there is very little circulation and
the corrosion on the inner side is such as to wear the boiler rapidly.
In the ash pit, ashes and any dampness that may be about the place also
causes rapid corrosion. The upper part of the tubes and tube sheet are
frequently injured; for instance, if the tubes pass all the way through
to the upper tube sheet, providing there is no cone top, when the fire
is first made under the boiler, combustion at times does not take place
until the gases pass nearly through the tubes. The water usually being
carried below the tube sheet there is a space left above the water
line, where there is neither steam nor water, and the heat is so great
that the ends of the tubes are burned and crystalized, and the tube
sheet is often cracked and broken by this excessive heat before the
steam is generated. The first difficulty is experienced in “the legs”
of the Portable Locomotive boiler—hence the general verdict of steam
users in favor of the round shell, many-tubed boiler.
PARTS OF THE TUBULAR BOILER.
THE SHELL. This is the round or cylindrical structure which is commonly
described as the boiler, in which are inserted the braces and tubes,
and which sustains the internal strain of the pressure of the steam,
the action of the water within, and the fire without.
THE DRUM. This part is sometimes called the dome, and consists of an
upper chamber riveted to the top of the boiler for the purpose of
affording more steam space.
THE TUBE SHEETS. These are the round, flat flanged sheets forming the
two ends of the boiler, into which the tubes are fastened.
THE MANHOLE COVER. This is a plate and frame commonly opening inwards
and large enough to admit a man into the interior of the boiler. These
openings are sometimes made on the top and sometimes at the end of the
boiler. Manhole openings in steam boilers should invariably be located
in the head of the boiler, except in rare cases that may arise, when
circumstances require it to be placed in the shell. The manhole, so
placed, will not materially reduce the strength of the boiler, and
from this position it can more readily be seen that the boiler is kept
in proper condition. The proper sizes for manholes are 9×5 and 10×16,
according to circumstances. These are amply large for general use and
no material advantage is gained by increasing them.
THE HAND HOLE PLATES. These are similar arrangements to the manhole
cover, except as to size. They are made large enough to admit the hand
into the boilers for the purpose of removing sediment and they are also
used for the purpose of inspecting the interior of the boiler. Two are
usually put in each boiler, one front and one in the rear.
THE BLOW OFF. This consists of pipes and a cock communicating with the
bottom of the boiler for the purpose of blowing off the boiler or of
running off the water when the former needs cleaning.
[Illustration: THE TRIPLE DRAUGHT TUBULAR BOILER.—Fig. 34.]
THE TRIPLE DRAUGHT TUBULAR BOILER.
This boiler, which is extensively used by the manufacturers of New
England, is, as will be seen by the illustration, of the horizontal
tubular class, and is essentially different from the well known type
only in the arrangement of the tubes. The method secures the passage
of the products of combustion through the same shell twice; forward
through a part of the tubes, and backwards through the remaining ones.
The manner of accomplishing this result can be best described by
explaining how a common tubular boiler may be remodelled so as to carry
out this principle.
[Illustration: Fig. 35.]
A cylindrical shell, as shown in Fig. 34—of sufficient size to encircle
about one-half of the tubes, is attached to _the outside of the rear
head_ below the water line, and extended backward to the back end of
the setting. The encircled tubes are lengthened and carried backward
to the same point; the extension is closed in and made to communicate
with the boiler proper; the inner tubes emerge to the flue leading to
the chimney and the old connection from the smoke arch is cut off. With
this arrangement, the outer tubes of the boiler—a cluster on each side
of the supplementary shell carry the products of combustion forward to
the front smoke arch, and the inner tubes carry them backward to the
chimney.
Fig. 35 exhibits the boiler in half section and shows the course of the
heat products through _one_ of the outer tubes and returning through
the boiler by _one_ of the inner cluster.
Fig. 36 (page 84) shows the boiler sectionally, over the bridge wall;
the _shaded_ tube ends exhibit the cluster which return the heat
products to the rear of the boiler, after being brought forward by the
two outer clusters which are left unshaded.
This arrangement of the tubes gives several advantages:
1. It enables an exceedingly high furnace temperature, without loss at
the chimney.
2. By dividing the heat into these currents a more equal expansion and
contraction is secured. This is an important point secured.
3. In this system the tubes are almost equally operative.
4. The extra body of water immediately over the furnace is both an
element of safety and a reservoir of power.
5. The outlet for the waste products of combustion is found in this
style of boiler in a more convenient position at _the rear end_ of the
boiler.
6. The boiler being self-contained, can be used in places where height
of story is limited.
[Illustration: Fig. 36.]
SPECIFICATION FOR 125 HORSE POWER BOILER.
_For one Horizontal Tubular Boiler_ 72 _inches diameter_ 18
_feet long for_…………………_of_………
Type.
The boiler to be of the Horizontal Tubular type with all castings and
mountings complete.
Dimensions.
Boiler 72 inches diameter and 18 feet long. Each boiler to contain 90
best lap welded tubes 3-1/2 inches diameter by 18 feet long, set in
vertical and horizontal rows with a space between them vertically and
horizontally of no less than one inch and one-quarter (1-1/4) except
central vertical space, which is to be three inches (3). No tube to
be nearer than two and one-half inches (2-1/2) to shell or boiler.
Holes through heads to be neatly chamfered off. All tubes to be set
by Dudgeon Expander and slightly flared at front end, turned over and
beaded down at back end.
Quality and Thickness of Steel Plates.
Shell plates to be 1/2-inch thick of homogeneous steel of uniform
quality having a tensile strength of not less than 65,000 lbs. Name of
maker, brand and tensile strength to be plainly stamped on each plate.
Heads to be of same quality as plates of shell in all particulars
3/4-inch thick. Bottom of shell to be of one plate, and no plate to be
less than 7 feet wide. Top of shell to be in three plates. All plates
planed before rolling, and all joints fullered not caulked.
Flanges.
All flanges to be turned in a neat manner to an internal radius of not
less than two inches (2) and to be clear of cracks, checks or flaws.
Riveting.
Boilers to be riveted with 3/4-inch rivet throughout. All girth seams
to be double riveted. All horizontal seams to be double riveted. Rivet
holes to be punched or drilled so as to come fair in construction. No
drift pins to be used in construction of the boilers.
Braces.
All braces to be of the crowfoot pattern, one and one eighth (1-1/8)
inch diameter and the shortest to be no less than four feet (4) long
and of sufficient number for thorough bracing, and to bear uniform
tension.
Manholes, Hand Holes and Thimbles.
One manhole in top of each boiler with heavy cast iron frame riveted on
middle of centre plate; one manhole near the bottom of each front head;
head reinforced with a wrought iron ring two inches (2) square, riveted
to heads with flush countersunk rivets two inches (2) pitch and to
have all the necessary bolts, plates, guards and gaskets; two six-inch
thimbles riveted to top of each boiler, each to have a planed face;
one heavy 6-inch flange on bottom of each boiler, 12 inches from back
end to centre of flange. There must be two braces, one on each side of
manhole in front head; also to have three braces opposite manhole on
back head below tubes.
Lugs.
Four (4) lugs riveted on each side of boilers, of good and sufficient
size, with six one-inch rivets in each lug.
Castings.
Each boiler to have a complete set of castings consisting of ornamental
flush fronts containing tube, fire and ash-pit doors, and provide
the best stationary grate bars as may be selected by buyer, with the
necessary fixtures, all bearing bars, britching plates, dead plates,
binder bars, back cleaning out doors with frames. Anchor bolts and
buck stays. The fire door to contain adjustable air opening and to be
protected with fire shields. One heavy cast iron arch over each boiler.
Testing.
Boilers to be tested with a water pressure of 200 lbs. per square inch
and certificate of such test having been made shall be furnished with
boiler. Test of boiler to be under direction of such steam boiler
Insurance Company as may be selected by buyer.
Quality and Workmanship.
All boilers to be made in the best workmanlike manner and all material
of their respective kinds to be of the best, and in strict accordance
with specification.
Fittings and Mountings.
The boiler to be furnished with the following: One four inch heavy
mounted safety valve. One six inch flanged globe valve. Two two inch
best globe valves. Two two inch check valves. One eight inch dial
nickel plated steam gauge. One low water alarm gauge. One set of fire
irons for two boilers consisting of hoe, poker, slice bar and shovel.
Drawings.
All drawings furnished for masons in setting the boilers.
Duty of Boiler.
The boiler to develop 120 horse power and to work under a constant
pressure varying from 125 to 150 lbs. to the square inch.
All rivets are to be 2-1/2 and 1-1/2 inch pitch. The pitch line of the
rivets to be not nearer 1-1/8 inches to the edge of the sheet.
To be 8 lug plates for each boiler not less than 2 feet long, 8 inches
wide, and one inch thick.
There shall be six 1 inch anchor rods running front to rear of each
boiler, in the brick work.
These boilers and all their fronts, fittings and connections will be
subject to the inspection of…………………
MARKS ON BOILER PLATES.
Something has been said under another heading of the nature and
requisite quality of the materials entering into the structure of the
boiler. Too much emphasis cannot be laid upon the necessity for the use
of the very best iron and steel that can be manufactured, and the most
skillful and thorough workmanship that can be performed in constructing
the boiler.
It is becoming the practice, both for land and marine boilers, for
boiler plate makers to furnish “test pieces” from each sheet or plate
that goes into the construction of a boiler, and a sheet showing the
tensile strength of each sheet or plate that enters into its make up.
But irrespective of this practice each plate entering into boiler
construction will be found to have one of the following marks, which
designate its quality and method of manufacture. The name “Charcoal
Iron” is used because in its manufacture wood charcoal is employed
instead of mineral fuel.
“Charcoal No. 1 Iron” (C. No. 1) is made entirely of charcoal iron. It
has a tenacity of 40,000 pounds per square inch in the direction of the
fibre. It is hard, but not very ductile, and should never be used for
flanging.
“Charcoal Hammered No. 1 Shell Iron” (C. H. No. 1 S.), although not
necessarily hammered, has been worked up before it is rolled into
plates. It has a tenacity of 50,000 to 55,000 pounds per square inch in
the direction of the fibre. It is rather hard iron, and should not be
flanged. It is used for the outside shell of boilers.
“Flange Iron” (C. H. No. 1 F.), is a ductile material which can be
flanged in every direction. It has a tenacity of 50,000 to 55,000
pounds per square inch along the fibre.
“Fire Box Iron” (C. H. No. 1 F. B.), is a harder quality, designed
especially to withstand the destructive effect of the impinging flame,
and is used for boxes and flue-sheets.
The letters in the brackets exhibit the plate stamp.
Cast iron and copper were used in an early day for steam boilers and
the former is still extensively used for certain forms of low pressure
steam heaters made for various purposes, such as green houses, etc.
CONSTRUCTION OF BOILERS.
In selecting a boiler, the most efficient design will be found to be
that in which _the greatest amount of shell surface is exposed to
direct heat_. It is the direct heating surface that does the bulk of
the work and every tendency to reduce it, either in the construction
or setting of the boiler, should be avoided. The smaller the amount of
surface enclosed by or in contact with the setting, the better results
will be obtained.
A boiler with a bad circulation is the bane of an engineer’s existence.
Proper circulation facilities constitute one of the chief factors in
the construction of a successful and economical boiler. In tubular
boilers the best practice places the tubes in vertical rows, leaving
out what would be the centre row. The circulation is up the sides of
the boiler and down the centre. Tubes set zig-zag to break spaces
impede the circulation and are not considered productive of the best
results.
The surface from which evaporation takes place should be made greater
as the steam pressure is reduced, that is to say, as the size of the
bubbles of steam become greater. To produce 100 lbs. of steam per hour
at atmospheric pressure this surface should not be less than 732 square
feet, which may be reduced to 146 square feet for steam at 75 lbs.
pressure, and to 73 feet for steam at a pressure of 150 lbs. It is for
this reason that triple-expansion engines can be worked with smaller
boilers than are required with engines using steam of lower pressure.
The amount of steam space to be permitted depends upon the volume
of the cylinders and the number of revolutions made per minute. For
ordinary engines it may be made a hundred times as great as the average
volume of steam generated per second.
A volume of heated water in a boiler performs the same office in
furnishing a steady supply of steam as a fly-wheel does to an engine in
insuring uniformity of speed; hence the centre space of a boiler should
be ample, in order to take advantage of this reserve force.
QUALITY OF STEEL PLATES.
Steel for boilers is always of the kind known as low steel, or
soft steel, and is, properly speaking, _ingot iron_, all of its
characteristics being those of a tenacious, bending, equal grained
iron, and quite different from true steels, such as knife blades,
cutting tools, etc., are composed of. Steel is rapidly displacing
iron in boiler construction, as it has greater strength for the same
thickness, than iron; and, except in rare instances, where the nature
of the water available for feed renders steel undesirable, iron should
not be used for making boilers, careful tests having shown it to be
vastly inferior to steel in many important features.
Good boiler steel up to one-half inch in thickness should be capable
of being doubled over and hammered down on itself without showing any
signs of fracture, and above that thickness it should be capable of
being bent around a mandrel of a diameter equal to one and one-half
times the thickness of the plate, to an angle of 180 degrees without
sign of distress. Such bending pieces should not be less in length than
sixteen times the thickness of the plate.
On this test piece the metal should show the following physical
qualities:
Tensile strength, 55,000 to 65,000 pounds per square inch.
Elongation, 20 per cent. for plates three-eighths inch thick or less.
Elongation, 22 per cent. for plates from three-eighths to three-fourths
inch thick.
Elongation, 25 per cent. for plates over three-fourths inch thick.
The cross sectional area of the test piece should be not less than
one-half of one square inch, _i.e._, if the piece is one-fourth inch
thick, its width should be two inches; if it be one-half inch thick,
its width should be one inch. But for heavier material the width shall
in no case be less than the thickness of the plate.
NICKEL STEEL BOILER PLATES.
It has been found that the addition of about three per cent. (3.16 to
3.32) of nickel to ordinary soft steel produces most favorable results;
thus it has been shown by Riley that a particular variety of nickel
steel presents to the engineer _the means of nearly doubling boiler
pressures without increasing weight or dimensions_.
In a recent experiment made with Bessemer steel rolled into
three-fourths inch plates from which a number of test specimens were
cut, the elastic limit was respectively 59,000 pounds and 60,000
pounds. The ultimate tensile strength was 100,000 pounds and 102,000
pounds, respectively. The elongation was 15-1/2 per cent. in each
specimen, and the reduction of area at fracture was 29-1/2 per cent.
and 26-1/2 per cent. respectively. These figures show that the elastic
limit and ultimate tensile strength was raised by the nickel alloy to
almost double the limits reached in the best grades of boiler plate
steel, and the elongation was reduced to a scarcely appreciable extent.
The experiment had for its object, the reproduction, as nearly as
possible, of the alloy used in the nickel steel armor plate made at Le
Creusot, France, and the result was reported to the Secretary of the
Navy at Washington. The new plate showed a percentage of 3.16 nickel,
as against 3.32 for the imported plate.
RIVETING.
When the materials are of best quality, then there only remains to
rivet and stay the boiler. _Riveting_ is of two kinds, single and
double. Fig. 37 shows the method of single riveting, and Figs. 38 and
39 show the plan and cross-section of double riveted sheets.
[Illustration: Fig. 37.]
_Double Riveting_ consists in making the joints of boiler work with
two rows of rivets instead of one—nearly always, horizontal seams
are double riveted as well as domes where they join upon the boiler.
Usually all girth seams,—those running round the body of the boiler,
are single riveted. The size of the rivets is in proportion to the
diameter of the boiler, being 5/8, 3/4 and 7/8 as required in the
specification.
Rivet holes are made by punching or drilling, according to the material
in which they are made. In soft iron and mild steel they may safely be
punched, but in metal at all brittle the holes should be drilled.
[Illustration: Fig. 38.]
Rivets are driven by hand, by steam riveting machines or by an
improved pneumatic machine which holds the sheet together and strikes
a succession of light blows to form the head of the rivet while
hot. Rivets are made both of iron and steel, and there are certain
well-known brands of such excellent quality that they are almost
exclusively used in boiler work.
A place where skill is shown in boiler construction is in laying out
the rivet holes, with a templet, so that the sheets come exactly
together with the holes so nearly opposite that the dreaded drift pin
does not have to be used.
In these figures the letters P and p refer to the “pitch of the
rivets,” _i.e._, the part from centre to centre, and the dimensions
given at the sides indicate the amount of lap given in inches and
tenths of inches—the diameter of the rivet (1″) is also shown, and the
turned over portion of the shank of the rivet is shown by dotted lines.
[Illustration: Fig. 39.]
No riveted boiler work can be considered fairly proportioned unless the
strength of the plate between the rivets is fully equal to the strength
of the rivets themselves. A margin (or net distance from outside of
holes to edge of plate) equal to the diameter of the drilled hole has
been found sufficient.
Rivets should be made of good charcoal iron or of a very soft mild
steel, running between 50,000 and 60,000 pounds tensile strength and
showing an elongation of not less than ninety per cent. in eight
inches, and having the same chemical composition as specified for
plates.
A long rivet, holding thick plates together, is rarely tight except
immediately under the head. The heads are set and the centre cooled
before the hole is properly filled. If it is a very long rivet there is
a chance of the contraction fracturing the head of the rivet. In the
Forth Bridge, which is made of very heavy plate girders, the rivets,
first carefully fitted, were driven tight into the holes, the burr
around the holes were removed, and the ends of the rivets heated to a
sufficient degree to enable them to be closed over.
A simple mathematical deduction shows that a circle seam has just
one-half the strain to carry as a longitudinal seam, under the same
pressure and with the same thickness of metal, hence the custom of
single riveting the former and double riveting the latter, or longwise
seams.
DIFFERENT MODES OF RIVETING.
+---------+----------+----------+-----------+
| CHAIN | ZIG ZAG | TREBLE | UNEQUAL |
|RIVETING.| RIVETING.| RIVETING.| PITCHES. |
+---------+----------+----------+-----------+
| O O | O | O O | O O O |
| | O | O | |
| O O | O | O O | O O |
| | O | O | |
| O O | O | O O | O O O |
| | O | O | |
| O O | O | O O | O O |
| | O | O | |
| O O | O | O O | O O O |
+---------+----------+----------+-----------+
In fig. 41 may be seen an example of zig-zag riveting.
[Illustration: Fig. 41.]
CAULKING.—By this is meant the closing of the edges of the seams of
boilers or plates. In preparing the seams for caulking, the edges are
first planed true inside and outside; and after the plates have been
riveted together, the edges are caulked or closed by a blunt chisel
about 1/4-inch thick at the edge, which should be struck with a 3 or
4-lb. hammer; sometimes one man doing the work alone and sometimes one
holding the chisel and another striking.
_Fullering_ a boiler plate is done by a round-nosed tool, while
_caulking_ is executed by a sharper instrument.
The thinnest plate which should be used in a boiler is one-fourth of an
inch, on account of the almost impossibility of caulking the seams of
thinner plates.
It is a rule well known to all practical boiler makers that the thinner
the metal (compatible with due strength) the longer the life of the
boiler under its varying stresses and the better the caulking will
stand.
STEEL RIVETS.
Hitherto there has been some prejudice against steel rivets, and
while this may have some foundation when iron plates are used, it is
certainly baseless when steel plates are concerned. The United States
government has clearly demonstrated this. All the ships of the new navy
have steel boilers, riveted with steel rivets, and an examination of
the character of the material prescribed and the severity of the tests
to which it is subjected show that these steel-riveted steel boilers
are probably the best boilers ever constructed.
United States Government Requirements for Boiler Rivets.
They are subjected to the most severe hammer tests, such as flattening
out cold to a thickness of one-half the diameter, and flattening out
hot to a thickness of one-third the diameter. In neither case must they
show cracks or flaws.
_Kind of Material._—Steel for boiler rivets must be made by either the
open-hearth or Clapp-Griffith process, and must not show more than .035
of one per centum of phosphorus nor more than .04 of one per centum of
sulphur, and must be of the best quality in other respects.
Each ton of rivets from the same heat or blow shall constitute a lot.
Four specimens for tensile tests shall be cut from the bars from which
the lot of rivets is made.
_Tensile Tests._—The rivets for use in the longitudinal seams of boiler
shells shall have from 58,000 to 67,000 pounds tensile strength, with
an elongation of not less than 26 per centum; and all others shall have
a tensile strength of from 50,000 to 58,000 pounds, with an elongation
of not less than 30 per centum in eight (8) inches.
_Hammer Test._—From each lot twelve (12) rivets are to be taken at
random and submitted to the following tests:
Four (4) rivets to be flattened out cold under the hammer to a
thickness of one-half the diameter without showing cracks or flaws.
Four (4) rivets to be flattened out hot under the hammer to a thickness
of one-third the diameter without showing cracks or flaws—the heat to
be the working heat when driven.
Four (4) rivets to be bent cold into the form of a hook with parallel
sides, without showing cracks or flaws.
_Surface Inspection._—Rivets must be true to form, free from scale,
fins, seams and all other unsightly or injurious defects.
In view of the fact that the government is using many hundred tons of
these rivets, shown by the records of the tests to be vastly superior
to any iron rivet made, in all the essentials of a good rivet, it would
seem that it would benefit the boiler maker, the purchaser of the
boiler and also the maker of the rivet by adopting a standard steel
rivet to be used in all steel boilers.
BRACING OF STEAM BOILERS.
The material of a boiler being satisfactory and the plates being
thoroughly and skillfully riveted there remains the important matter
of strengthening the boiler against the enormous internal pressure not
altogether provided for.
[Illustration: Fig. 42.]
To illustrate the importance of attention to this point it may be
remarked that a boiler eighteen feet in length by five feet in
diameter, with 40 four-inch tubes, under a head of 80 pounds of steam,
has a pressure of nearly 113 tons on each head, 1,625 tons on the shell
and 4,333 tons on the tubes, making a total of 6,184 tons on the whole
of the exposed surfaces.
Not only is this immense force to be withstood, but owing to the fact
that the boiler grows weak with age—_a safety factor_ of six has been
adopted by inspectors, _i.e._, the boiler must be made six times as
strong as needed in every day working practice.
[Illustration: Fig. 43.]
BRACES IN THE BOILER.—The proper bracing of flat surfaces
exposed to pressure, is a matter of the greatest importance, as the
power of resistance to bulging possessed by any considerable extent
of such a surface, made as they must be in the majority of cases of
thin plates, is so small that _practically the whole load has to be
carried by the braces_. This being the case, it is evident that as
much attention should be given to properly designing, proportioning,
distributing and constructing the brace as to any other portion of the
boiler.
All flat surfaces should be strongly supported with braces of the best
refined iron, or mild steel, having a tensile strength of not less than
58,000 lbs. to the square inch. These braces must be provided with crow
feet or heavy angle iron properly distributed throughout the boiler.
[Illustration: Fig. 44.]
Fig. 42 shows the method usually followed in staying small horizontal
tubular boilers. The cut represents a 36-inch head and there are five
braces in each head: two short ones and three long ones. The braces
should be attached to shell and head by two rivets at each end. The
rivets should be of such size that _the combined area_ of their shanks
will be at least equal to the body of the brace, and their length
should be sufficient to give a good large head on the outside to
realize strength equal to the body of the brace.
In boilers with larger diameters, 5 to 8 feet, stay ends are made of
angle or T iron; by this arrangement the stays can be placed further
apart, the angle irons very effectively staying the plate between the
stays, and thus affording more room in the body of the boiler. The size
of the stays have to be increased in proportion to the greater load
they have to sustain. See Fig. 43.
In a 66-inch boiler it is proper to have not less than 10 braces in
each head, none under three feet in length, made of the best round iron
one inch in diameter, with ends of braces made of iron 2-1/2 × 1/2
inches with three pieces of T iron riveted to head above the tubes to
which the braces are attached with suitable pins or turned bolts. See
Fig. 44.
STAYING OF FLAT SURFACES.—When boilers are formed principally of
flat plates, like low-pressure marine boilers, or the fire-boxes of
locomotive boilers, the form contributes nothing to the strength, which
must, therefore, be provided for by staying the opposite furnaces
together. Fig. 45 shows the arrangement of the stays in a locomotive
fire-box. They are usually pitched about 4 inches from centre to
centre, and are fastened into the opposite plates by screwing, as
shown, the heads being riveted over. Each stay has to bear the pressure
of steam on a square _aa_, and the sectional area of the stay must be
so chosen that the tensile strength will be sufficient to bear the
strain with the proper factor of safety.
[Illustration: Fig. 45.]
If the spaces between the stays are too great, or the plate too thin,
there is a danger of the structure yielding through the plate bulging
outwards between the points of attachment of the stays, thus allowing
the latter to draw through the screwed holes made in the plates.
In designing boilers with stayed surfaces, care should be taken that
_the opposite plates connected by any system of stays should, as far as
possible, be of equal area_, otherwise there is sure to be an unequal
distribution of load in the stays, some receiving more than their
proper share, and moreover, the least supported plate is exposed to the
danger of buckling.
RULE FOR FINDING PRESSURE OR STRAIN ON BOLTS.
The absolute stress or strain on a flat surface of a steam boiler,
which is carried by the stays, can be easily determined by a simple
rule:
Choose 3 stays as A B C in Fig. 46, measure from A to B _in inches_,
and from A to C. Multiply these two numbers together and the result
is the number of square inches of surface depending upon one bolt for
supporting strength.
EXAMPLE.
Suppose the stays measure from center to center 5 inches each way with
steam at 80 lbs., then
5 × 5 = 25 × 80 = 2,000 lbs. borne by 1 stay.
NOTE.
The pressure on the surface does not include the space occupied by the
area of the stay bolt, hence, to be absolutely correct that must be
deducted.
[Illustration: Fig. 46.]
GUSSET STAYS.
The flat ends of cylindrical boilers are, especially in marine boilers,
stayed to the round portions of triangular plates of iron called gusset
stays. These are simply pieces of plate iron secured to the boiler
front or back, near the top or bottom, by means of two pieces of angle
iron, then carried to the shell plating, and again secured by other
pieces of angle bar. This arrangement is shown in Fig. 47.
[Illustration: Fig. 47.]
PALM STAYS.—These are shown in Fig. 48, and are often used in the same
position as a gusset stay; that is, from the back or front end of the
boiler to the shell plates; they are sometimes used to stay the curved
tops of combustion chambers.
[Illustration: Fig. 48.]
The two opposite ends are also stayed together by long bar stays,
running the whole length of the boiler, it is dangerous, however, to
trust too much to the latter class of stays; for, in consequence of the
alternate expansion and contraction which takes place every time the
boiler is heated and cooled, they have a tendency to work loose at the
joints; and if the portion of the boiler in which they are situated
should happen to be hotter than the outside shell, they have a tendency
to droop and are then perfectly useless.
RIVETED OR SCREW STAYS.
[Illustration: Fig. 49.]
In addition to palm and gusset stays, there are in use riveted or
screwed stays, as shown in Fig. 49.
This would not answer in furnaces, owing to the burning off of the
heads, hence driven stays are used there.
[Illustration: Fig. 50.]
These screwed stays, shown in Fig. 50, are used (in marine and similar
boilers) between the combustion chamber back and boiler back and also
between the sides of the combustion chambers.
The general plan is to have a large nut and washer inside and outside
the boiler with the outside washer considerably larger than the inside,
so as to hold more efficiently the back and front ends together.
In marine boilers it is customary to place the stays 15 to 18 inches
apart for ease of access to the parts of the boiler, and to make them
of 2-1/4 to 2-1/2 inch iron of the best quality.
INSPECTOR’S RULES RELATING TO BRACES IN STEAM BOILERS, ALSO TO BE
OBSERVED BY ENGINEERS.
Where flat surfaces exist, the inspector must satisfy himself that the
spacing and distance apart of the bracing, and all other parts of the
boiler, are so arranged that all will be of not less strength than the
shell, and he must also after applying the hydrostatic test, thoroughly
examine every part of the boiler.
No braces or stays employed in the construction of marine boilers shall
be allowed a greater strain than six thousand pounds per square inch
of section, and no screw stay bolt shall be allowed to be used in the
construction of marine boilers in which salt water is used to generate
steam, unless said stay bolt is protected by a socket. But such screw
stay bolts, without sockets, may be used in staying the fire boxes
and furnaces of such boiler, and not elsewhere, when fresh water is
used for generating steam in said boiler. Water used from a surface
condenser shall be deemed fresh water. And no brace or stay bolt used
in a marine boiler will be allowed to be placed more than eight and
one-half inches from centre to centre, except that flat surfaces,
other than those on fire boxes, furnaces and back connections, may
be reinforced by a washer or =T= iron of such size and thickness as
would not leave such flat surface unsupported at a greater distance,
in any case, than eight and one-half inches, and such flat surface
shall not be of less strength than the shell of the boiler, and able to
resist the same strain and pressure to the square inch, and no braces
supporting such flat reinforced surfaces, will be allowed more than 16
inches apart.
In allowing the strain on a screw stay bolt, the diameter of the same
shall be determined by the diameter at the bottom of the thread. Many
State laws and City ordinances allow a strain of seven thousand five
hundred pounds per square inch of section on good bracing without
welds. The following table gives the safe load of round iron braces or
stays.
DIAMETER OF BRACE.
----------+----+----+----+----+----+------+------+------+------+-----
Tensile | | | | | | | | | |
strength | | | | | | | | | |
per square|1/2″|5/8″|3/4″|7/8″| 1″ |1-1/8″|1-1/4″|1-1/2″|1-3/4″| 2″
inch of | | | | | | | | | |
section | | | | | | | | | |
allowed | | | | | | | | | |
----------+----+----+----+----+----+------+------+------+------+-----
5000 | 981|1533|2208|3006|3927| 4970 | 6136 | 8835 |12026 |15708
6000 |1178|1840|2650|3607|4712| 5964 | 7363 |10602 |14431 |18849
7000 |1374|2567|3092|4209|5497| 6958 | 8590 |12369 |16837 |21991
7500 |1472|2750|3313|4509|5890| 7455 | 9204 |13253 |18039 |23562
----------+----+----+----+----+----+------+------+------+------+-----
SHOP NAMES FOR BOILER BRACES.—1. Gusset brace (fig. 47). 2. Crowfoot
brace. 3. Jaw brace (fig. 44). 4. Head to head brace (fig. 50). These
shop terms refer to braces used in the tubular form of boiler.
A STAY AND A BRACE in a steam boiler fulfil the same office, that of
withstanding the pressure exerted outward of the expanded and elastic
steam.
SOCKET BOLTS are frequently used instead of the screw stay between the
inside and outside plates that form the centre space. Socket bolts are
driven hot the same as rivets.
The method of bracing with =T= bars is considered the best; the bars
make the flat surface rigid and unyielding even before the brace is
applied. The braces should be spaced about 8 inches apart on the =T=
bar and 7 inches from the edge of the flange =T= the bar should be 4″
× 4-1/2″ =T= iron and riveted to the head or flat surface with 11/16″
rivets spaced 4-1/2 inches apart.
HOLLOW STAY BOLTS are used in locomotive fire boxes to show when
fracture has occurred by permitting an escape of steam or water.
The flange of a boiler head 1/2″ thick will amply support 6 inches from
the edge of the flange.
A radius of 2 inches is ample for bend of flange on the head. The lower
braces should be started 6 inches above the top row of tubes. Braces
should be fitted so as to have a straight pull, _i.e._ parallel with
the boiler shell. The heads of the boiler should be perfectly straight
before the braces are fitted in place. Gusset brace plates should not
be less than 30 inches long and 14 inches wide. Braces are best made of
1 inch =O= iron of highest efficacy with tensile strength of not less
than 58,000 lbs. to the square inch.
[Illustration: Fig. 51.]
The riveted stay shown in Fig. 51, consists of a long rivet, passed
through a thimble or distance piece of wrought iron pipe placed between
plates, to be stayed together, and then riveted over in the usual
manner.
An ingenious device is in use to show when a bolt has broken. A small
hole is drilled into the head, extending a little way beyond the plate,
and as experience shows that the fracture nearly always occurs _next to
the outside plate_, that is the end taken for the bored out head: when
the bolt is broken the rush of steam through the small hole shows the
danger without causing serious disturbance.
Even where the best of iron is used for stay bolts they should never be
exposed to more than 1/10th or 1/12th their breaking strength.
The stays should be well fitted, and each one carefully tightened, and,
as far as possible each stay in a group _should have the same regular
strain upon it_—if the “pull” all should come on one the whole are
liable to give way.
DIMENSIONS AND SHAPE OF ANGLE AND T IRON.
[Illustration: Fig. 52.]
The condition of a boiler can be learned by tapping on the sheets,
rivets, seams, etc., to ascertain whether there are any broken stays,
laminated places, broken rivets, etc.
[Illustration: Fig. A.]
[Illustration: Fig. B.]
Fig. A represents the method of preparing testing pieces of boiler
plate, for the machines prepared specially to measure their elongation
before breaking, and also the number of pounds they will bear
stretching before giving way. Fig. B exhibits the same with reference
to the brace and other =O= iron.
RULES AND TABLES
FOR DETERMINING AREAS AND CALCULATING THE CONTENTS OF STEAM AND WATER
SPACES IN THE STEAM BOILER.
In order to ascertain the number of braces, which are necessary to
strengthen that part of the boiler head, which is not stayed by the
tubes, it is first necessary to know its area; the part to be stayed is
_a segment of a circle_.
_The length of the segment_ is measured above the top row of the tubes,
and its _height or width_ is equal to the distance from the top of the
tubes to the top of the boiler shell.
Since, however, part of this segment is braced by the boiler shell,
and also by the top row of the tubes, it has been generally agreed
that the length of the segment should be measured two inches above the
tubes, and the height or width, should be measured from a line, drawn
two inches above the tubes, to a point within three inches from the top
of the boiler shell, as shown in the illustration by the dotted line.
Thus, referring to Fig. D, the length of the segment is equal to l, and
the height is equal to h.
RULE. The area of a segment may be obtained, very approximately, by
_dividing the cube of the width (or height) by twice the length of
the chord, and adding to the quotient the product of the width into
two-thirds of the chord_.
EXAMPLE. If we suppose the height h of the segment in Fig. D to be
equal to 18 inches, and the length l to be equal to 48 inches, we have
18³ ÷ (48 × 2) + (48 × 2/3 × 18) = 60.7 + 576.0 = 636.7 square inches.
[Illustration: Fig. C. Fig. D.]
In order to calculate the contents of the steam and water spaces of a
boiler, the same rule, as above, may be employed. The volume of the
steam space may be readily obtained by the above rule, _taking the
distance from the water level to the top of the shell for the height,
and the diameter of the shell, measured at the water line, for the
length of the segment lines_.
The area of the segment thus found, expressed in square inches, divided
by 144, and multiplied by the length of the boiler in feet, is equal to
_the steam space, in cubic feet_, this result is slightly reduced by
the space occupied by the braces.
In order to find the volume of the water space, it is first necessary
to _find the total area of the boiler head_, and this _minus the area
of the segment above the water line_, is equal to the area of the
segment below the water line. From this must also be subtracted _the
combined cross sectional area of the tubes_.
Thus, the rule for finding the volume of the steam space in cubic feet.
1. _Find the area of the segment of the boiler head, above the water
line, in square inches._
2. _Divide this by 144, and multiply the quotient by the length of the
boiler in feet._
To find the volume of the waterspace in cubic feet.
1. _Find the area of the boiler head in square inches._
2. _Multiply the square of the outside diameter of one tube by .7854,
and multiply this by the number of tubes, and add to the product, the
area of the segment above the waterline_.
3. _Subtract 2 from 1, and divide the remainder by 144._
4. _Multiply the quotient by the length of the boiler in feet._
To find the number of braces, necessary for the flat surface above the
tubes.
1. _Find the area of the segment of the boiler head, which is to be
braced, in square inches._
2. _Multiply the area, thus found, by the steam pressure in pounds per
square inch._
3. _Multiply the cross sectional area of one brace by the number of
pounds, which it is allowed to carry, per square inch of section._
4. _Divide product 2 by product 3, and the result is the number of
braces, required for the head_.
Table No. 1 gives the total area in square inches. No. 2, areas to
be braced. No. 3, number of braces of one inch round iron required,
allowing seven thousand five hundred pounds per square inch of section
at one hundred pounds steam pressure.
Table No. 3 will be found of more practical use than Table 2, for it
gives directly the number of braces required in any given boiler,
instead of the area to be braced. It was calculated from Table 2. The
iron used in braces will safely stand a continuous pull of 7,500
pounds to the square inch, which is the figure used in computing the
foregoing table. A round brace an inch in diameter has a sectional area
of .7854 of an inch, and the strain that it will safely withstand is
found by multiplying .7854 by 7,500, which gives 5,890 pounds as the
safe working strain on a brace of one-inch round iron.
In a 60-inch boiler, whose upper tubes are 28 inches below the shell,
the area to be braced is, according to table 2, 930 square inches. If
the pressure at which it is to be run is 100 pounds to the square inch,
the entire pressure on the area to be braced will be 93,000 pounds, and
this is the strain that must be withstood by the braces. As one brace
of inch-round iron will safely stand 5,890 pounds, the boiler will need
as many braces as 5,890 is contained in 93,000, which is 15.8. That is,
16 braces will be required. The table is made out on the basis of 100
lbs. pressure to the square inch, because that is a very convenient
number.
TABLE NO. 1. TOTAL AREA ABOVE TUBES OR FLUES.
(SQUARE INCHES.)
----------+-----------------------------------------
Height | DIAMETER OF BOILER IN INCHES.
from tubes+-----+-----+-----+-----+-----+-----+-----
to shell.| 36 | 42 | 48 | 54 | 60 | 66 | 72
----------+-----+-----+-----+-----+-----+-----+-----
15 | 389 | | | | | |
16 | 419 | | | | | |
17 | 458 | 526 | | | | |
18 | | 566 | 620 | 667 | | |
19 | | 608 | 667 | 720 | | |
20 | | 650 | 714 | 770 | 824 | |
21 | | | 756 | 824 | 882 | |
22 | | | 808 | 878 | 937 | |
23 | | | | 930 | 996 |1059 |
24 | | | | 982 |1056 |1121 |
25 | | | |1037 |1116 |1184 |
26 | | | |1090 |1209 |1252 |1324
27 | | | |1145 |1234 |1316 |1394
28 | | | | |1291 |1381 |1465
29 | | | | |1352 |1445 |1536
30 | | | | |1414 |1511 |1608
31 | | | | | |1576 |1674
32 | | | | | |1641 |1746
33 | | | | | | |1818
34 | | | | | | |1896
----------+-----+-----+-----+-----+-----+-----+-----
TABLE 2. AREAS TO BE BRACED. (SQUARE INCHES.)
----------+-----------------------------------------
Height | DIAMETER OF BOILER IN INCHES.
from tubes+-----+-----+-----+-----+-----+-----+-----
to shell.| 36 | 42 | 48 | 54 | 60 | 66 | 72
----------+-----+-----+-----+-----+-----+-----+-----
15 | 206 | | | | | |
16 | 235 | | | | | |
17 | 264 | 297 | | | | |
18 | | 331 | 365 | 396 | | |
19 | | 316 | 404 | 439 | | |
20 | | 401 | 444 | 483 | 519 | |
21 | | | 485 | 528 | 568 | |
22 | | | 526 | 574 | 618 | |
23 | | | | 620 | 668 | 714 |
24 | | | | 667 | 720 | 769 |
25 | | | | 714 | 772 | 825 |
26 | | | | 761 | 824 | 882 | 937
27 | | | | 809 | 877 | 940 | 998
28 | | | | | 930 | 998 |1061
29 | | | | | 983 |1056 |1124
30 | | | | |1037 |1115 |1187
31 | | | | | |1174 |1252
32 | | | | | |1234 |1317
33 | | | | | | |1382
34 | | | | | | |1447
----------+-----+-----+-----+-----+-----+-----+-----
TABLE 3. NUMBER OF BRACES REQUIRED, AT 100 LBS. PRESSURE.
----------+-----------------------------------------
Height | DIAMETER OF BOILER IN INCHES.
from tubes+-----+-----+-----+-----+-----+-----+-----
to shell.| 36 | 42 | 48 | 54 | 60 | 66 | 72
----------+-----+-----+-----+-----+-----+-----+-----
15 | 3.5 | | | | | |
16 | 4.0 | | | | | |
17 | 4.5 | 5.0 | | | | |
18 | | 5.6 | 6.2 | 6.7 | | |
19 | | 6.2 | 6.9 | 7.5 | | |
20 | | 6.8 | 7.5 | 8.2 | 8.9 | |
21 | | | 8.2 | 9.0 | 9.6 | |
22 | | | 8.9 | 9.8 |10.5 | |
23 | | | |10.5 |11.3 |12.1 |
24 | | | |11.3 |12.2 |13.1 |
25 | | | |12.1 |13.1 |14.0 |
26 | | | |12.9 |14.0 |15.0 |15.9
27 | | | |13.7 |14.9 |16.0 |16.9
28 | | | | |15.8 |16.9 |18.0
29 | | | | |16.7 |17.9 |19.1
30 | | | | |17.6 |18.9 |20.2
31 | | | | | |19.9 |21.3
32 | | | | | |21.0 |22.4
33 | | | | | | |23.5
34 | | | | | | |24.9
----------+-----+-----+-----+-----+-----+-----+-----
In Table 2 this calculation has been made for all sizes of boilers that
are ordinarily met with. The area to be braced has been calculated
as above in each case, the two-inch strip above the tubes, and the
three-inch strip around the shell being taken into account. As an
example of its use, let us suppose that upon measuring a boiler we find
that its diameter is 54 inches, and that the distance from the upper
tubes to the top of the shell is 25 inches. Then by looking in the
table under 54″ and opposite 25″ we find 714, which is the number of
square inches that requires staying on each head.
BOILER TUBES.
TABLE.
_Dimensions of Lap Welded Boiler Tubes._
--------------+---------+----------
Size outside | Wire |Weight per
diameter. | Gauge. | foot.
--------------+---------+----------
1 inch. | 15 | 0.708
1-1/4 „ | 15 | 0.9
1-1/2 „ | 14 | 1.250
1-3/4 „ | 13 | 1.665
2 „ | 13 | 1.981
2-1/4 „ | 13 | 2.238
2-1/2 „ | 12 | 2.755
2-3/4 „ | 12 | 3.045
3 „ | 12 | 3.333
3-1/4 „ | 11 | 3.958
3-1/2 „ | 11 | 4.272
3-3/4 „ | 11 | 4.590
4 „ | 10 | 5.320
4-1/2 „ | 10 | 6.010
5 „ | 9 | 7.226
6 „ | 8 | 9.346
7 „ | 8 | 12.435
8 „ | 8 | 15.109
9 „ | 7-1/2|
10 „ | 6-1/2|
--------------+---------+----------
The above is the regular manufactures’ list of sizes and weights.
NOTE.
Boiler tubes are listed and described from the _outside diameter_. This
should be noted, as gas-pipe is described from the _inside diameter_.
Thus a 1-inch gas-pipe is nearly 1-1/4 outside diameter while a 1-inch
boiler tube is exactly one inch. Another difference between the two
consists in the fact that the outside of boiler tubes is rolled smooth
and even; gas-pipe is left comparatively rough and uneven.
When the boiler tubes are new and properly expanded there is a large
reserve or surplus of holding power for that part of the tube sheet
supported by them, this has been proved by experiment made by chief
engineer W. H. Stock, U. S. N., as shown in the following
TABLE OF HOLDING POWER OF BOILER TUBES.
--------------+--------+---------+-------+--------------------------
Outside |Area of |Thickness|Strain |
diameter | cross | of tube | in | Method of Fastening.
of end of tube|section | plate .|pounds.|
where fracture|of body | |Mean |
took place. |of tube.| |result.|
--------------+--------+---------+-------+--------------------------
Inches. |Sq. ins.| Inches. |Pounds.|
2-5/8 | .981 | 7/16 | 22650 |Expanded by Dudgeon tool,
| | | | end riveted over.
2-5/8 | .981 | 7/16 | 22150 |Expanded by Dudgeon tool,
| | | | end partly riveted over.
2-3/8 | .981 | 3/8 | 25525 |Expanded by Dudgeon tool,
| | | | end riveted over.
2-3/8 | .981 | 3/8 | 29675 |Expanded by Dudgeon tool,
| | | | ferruled, not riveted
| | | | over.
2-3/8 | .981 | 3/8 | 13050 |Simply expanded by Dudgeon
| | | | tool.
--------------+--------+---------+-------+--------------------------
Mr. C. B. Richards, consulting engineer at Colt’s Armory at Hartford,
Conn., made some experiments as to the holding power of tubes in
steam boilers, with the following results: The tubes were 3 inches
in external diameter, and 0.109 of an inch thick, simply expanded
into a sheet 3/8 of an inch thick by a Dudgeon expander. The greatest
stress without the tubes yielding in the plate was 4,500 pounds, and
at 5,000 pounds was drawn from the sheet. These experiments were
repeated with the ends of the tubes which projected through the sheet
three-sixteenths of an inch, being flared so that the external diameter
in the sheet was expanded to 3.1 inches. The greatest stress without
yielding was 18,500 pounds; at 19,000 pounds yielding was observed; and
at 19,500 pounds it was drawn from the sheet. The force was applied
parallel to the axis of the tube, and the sheet surfaces were held at
right angles to the tube axis.
NOTE.
When the tube sheet and tube ends near the sheet become coated with
scale or the tubes become overheated, the holding power of the tubes
becomes largely reduced, and caution must be used in having the tube
ends re-expanded and accumulated scale removed.
NOTE 2.—In considering the stress or strain upon the expanded
or riveted over ends of a set of boiler tubes, it may be remembered
that the strain to be provided against is only that coming upon tube
plate, exposed to pressure, _between the tube ends_—the space occupied
by the tubes has no strain upon it.
The gauge to be employed by inspectors to determine the thickness of
boiler plates will be any standard American gauge furnished by the
Treasury Department.
All samples intended to be tested on the Riehle, Fairbanks, Olson, or
other reliable testing machine, must be prepared in form according to
the following diagram, viz.: eight inches in length, two inches in
width, cut out their centres as indicated.
[Illustration: Fig. E.]
PORTIONS OF THE MARINE BOILER WHICH BECOME THIN BY WEAR.
These are generally situated, 1st, at or a little above the line of
fire bars in the furnace; 2d, the ash pits; 3d, combustion chamber
backs; 4th, shell at water line; 5th, front and bottom of boiler.
The thinning can usually be detected by examination, sounding with a
round nosed hammer, or drilling small holes in suspected parts not
otherwise accessible for examination.
EXAMPLES OF CONSTRUCTION AND DRAWING
+--------+--------+---------+---------+
| _d_ | _t_ | _d_ | _t_ |
+--------+--------+---------+---------+
| _9/16″_| _1/4″_ | _15/16″_| _5/8″_ |
+--------+--------+---------+---------+
|_11/16″_| _5/16″_|_1-1/16″_| _3/4″_ |
+--------+--------+---------+---------+
| _3/4″_ | _3/8″_ |_1-1/8″_ | _7/8_ |
+--------+--------+---------+---------+
| _7/8″_ | _1/2″_ |_1-3/16″_| _1″_ |
+--------+--------+---------+---------+
_d_ = DIAM. OF RIVET.
_t_ = THICKNESS OF PLATE.
The small table above is of use in this and the four succeeding pages;
in all places in the drawings where “d” is used it indicates _the
diameter of the rivet_; “t” means _the thickness of the plate_; “p”
stands for _pitch_. The table also shows the proportion of rivet to the
plate—thus, a 1/4-inch plate requires a 9/16 rivet, etc.
It is recommended, in view of the increased disposition on the part of
official examiners to test the applicant’s knowledge of drawing, for
any one interested, to redraw to a _full size_ all the rivets, plates,
and methods of joining the two contained on pages 113-116.
[Illustration: Fig. 53.]
[Illustration: Fig. 54.]
The figures 53 to 60 will be understood without much explanation.
In figures 53 and 54 _the cup head, the conical head and pan head
rivets_ are shown.
Figs. 55 and 56 exhibit the details (and drawings) of single and double
riveting. Where the cut reads p = (2-1/2)d, it means that the distance
from the centre of one rivet to the centre of the next shall be 2-1/2
the diameter of the rivet, see example, page 115.
[Illustration: Fig. 55.]
[Illustration: Fig. 56.]
EXAMPLE.
If the size of the rivet used is 7/8ths, then 7/8 × 2-1/2 = 2-2/10
inches nearly, and this gives the proportionate strength of the plate
and the rivet, see page 113.
[Illustration: Fig. 57.]
Figs. 57, 58, 59 and 60 show quite clearly the joints and rivet work
done in locomotive and marine work. Fig. 60 shows method of riveting 3
plates, A, B, and C, together.
[Illustration: Fig. 58.]
[Illustration: Fig. 59.]
[Illustration: Fig. 60.]
RULE FOR SAFE INTERNAL PRESSURE
The safe internal pressure on cylindrical shells is found according to
the following rule, which has been adopted by the United States Board
of Supervising Inspectors, and any boiler shell not found in the tables
can be determined by this rule.
RULE.—Multiply one-sixth of the lowest tensile strength found stamped
on any plate in the cylindrical shell by the thickness—expressed
in inches or parts of an inch—of the thinnest plate in the same
cylindrical shell, and divide by the radius or half diameter—also
expressed in inches—and the result will be the pressure allowable per
square inch of surface for single riveting, to which add twenty per
centum for double riveting.
The hydrostatic pressure applied, under this table and rule, must be in
the proportion of one hundred and fifty pounds to the square inch, to
one hundred pounds to the square inch of the working pressure allowed.
EXAMPLE.
What pressure should be allowed to be carried on a boiler 60″ diameter,
made of plates 3/8″ thick, having a tensile strength of 60,000 pounds?
Now then:
6)60,000
------
10,000
3
------
8)30,000
------
Half diam. 30)3750(125. lbs.--if single riveted.
30
----
75
60
----
150 125 + 25 lbs. (20 feet) = 150 for
150 double riveted.
TABLES SAFE INTERNAL PRESSURE.
----------+---------+---------------+---------------+---------------
| | Pressure. | Pressure. | Pressure.
| +-------+-------+-------+-------+-------+-------
Diameter |Thickness|Single |Double |Single |Double |Single |Double
of | of |Riveted|Riveted|Riveted|Riveted|Riveted|Riveted
Boiler. | Plates. +-------+-------+--------+------+-------+-------
| |45,000 Tensile |50,000 Tensile |55,000 Tensile
| | Strength. | Strength. | Strength.
| | 1-6, 7,500 | 1-6, 8,333.3 | 1-6, 9,166.6
----------+---------+-------+-------+-------+-------+-------+-------
36 Inches.| .21 | 87.5 |105. | 97.21 |116.65 |106.94 |128.3
| .23 | 95.83 |114.99 |106.47 |127.76 |117.12 |140.54
| .25 |104.16 |124.99 |115.74 |138.88 |127.31 |152.77
| .26 |108.33 |129.99 |120.37 |144.44 |132.4 |158.88
| .29 |120.83 |144.99 |134.25 |161.11 |147.68 |177.21
| .33 |137.5 |165. |152.77 |183.32 |168.05 |201.66
| .35 |145.83 |174.99 |162.03 |194.43 |178.23 |213.87
| .375 |156.25 |187.5 |173.61 |208.33 |190.97 |229.16
+---------+-------+-------+-------+-------+-------+-------
| |60,000 Tensile |65,000 Tensile |70,000 Tensile
| | Strength. | Strength. | Strength.
| | 1-6, 10,000 | 1-6, 10,833.3 | 1-6, 11,666.6
| +-------+-------+-------+-------+-------+-------
| .21 |116.66 |139.99 |126.38 |151.65 |136.11 |163.33
| .23 |127.77 |153.32 |138.41 |166.09 |149.07 |178.88
| .25 |138.88 |166.65 |150.46 |180.55 |162.03 |194.43
| .26 |144.44 |173.32 |156.48 |187.77 |168.51 |202.21
| .29 |161.11 |193.33 |174.53 |209.43 |187.90 |225.48
| .33 |183.33 |219.99 |198.61 |238.33 |213.88 |256.65
| .35 |194.44 |233.32 |210.64 |252.76 |226.84 |272.20
| .375 |208.33 |249.99 |225.69 |271.82 |243.05 |291.66
----------+---------+-------+-------+-------+-------+-------+-------
| |45,000 Tensile |50,000 Tensile |55,000 Tensile
| | Strength. | Strength. | Strength.
| | 1-6, 7,500 | 1-6, 8,333.3 | 1-6, 9,166.6
| +-------+-------+-------+-------+-------+-------
40 Inches.| .21 | 78.75 | 94.50 | 87.49 |104.98 | 96.24 |115.48
| .23 | 86.25 |103.5 | 95.83 |114.99 |105.41 |126.49
| .25 | 93.75 |112.5 |104.16 |124.99 |114.58 |137.49
| .26 | 97.5 |117. |108.33 |129.99 |119.16 |142.99
| .29 |108.75 |130.5 |120.83 |144.99 |132.91 |159.49
| .3125 |117.18 |140.61 |130.2 |156.24 |143.22 |171.86
| .33 |123.75 |148.5 |137.49 |164.98 |151.24 |181.48
| .35 |131.25 |157.5 |145.83 |174.99 |160.41 |192.49
| .375 |140.62 |168.74 |156.24 |187.48 |171.87 |206.24
+---------+-------+-------+-------+-------+-------+-------
| |60,000 Tensile |65,0000 Tensile|70,000 Tensile
| | Strength. | Strength. | Strength.
| | 1-6, 10,000 | 1-6, 10,833.3 | 1-6, 11,666.6
| +-------+-------+-------+-------+-------+-------
| .21 |105. |126. |113.74 |136.48 |122.49 |146.98
| .23 |115. |138. |124.58 |149.49 |134.16 |160.99
| .25 |125. |150. |135.41 |162.49 |145.83 |174.99
| .26 |130. |156. |140.83 | 68.99 |151.66 |181.99
| .29 |145. |174. |157.08 |188.49 |169.16 |202.99
| .3125 |156.25 |187.45 |169.27 |203.12 |182.29 |218.74
| .33 |165. |198. |178.74 |214.48 |192.49 |230.98
| .35 |175. |210. |189.58 |227.49 |204.16 |244.99
| .375 |187.5 |225. |203.12 |243.74 |218.74 |262.48
----------+---------+-------+-------+-------+-------+-------+-------
| |45,000 Tensile |50,000 Tensile |55,000 Tensile
| | Strength. | Strength. | Strength.
| | 1-6, 7,500 | 1-6, 8,333.3 | 1-6, 9,166.6
| +-------+-------+-------+-------+-------+-------
42 Inches.| .21 | 75. | 90.00 | 83.32 | 99.99 | 91.66 |109.99
| .23 | 82.14 | 98.56 | 91.23 |109.51 |100.39 |120.46
| .25 | 89.28 |107.13 | 99.2 |119.04 |109.12 |130.94
| .26 | 92.85 |111.42 |103.17 |123.8 |113.49 |136.18
| .29 |103.57 |124.28 |115.07 |138.08 |126.57 |151.85
| .3125 |111.6 |133.92 |124. |148.8 |136.4 |163.68
| .33 |117.85 |141.42 |130.94 |157.12 |144.04 |172.84
| .35 |125. |150. |138.88 |166.65 |152.77 |183.32
| .375 |133.92 |160.7 |148.8 |178.56 |163.68 |196.40
+---------+-------+-------+-------+-------+-------+-------
| |60,000 Tensile |65,000 Tensile |70,000 Tensile
| | Strength. | Strength. | Strength.
| | 1-6, 10,000 | 1-6, 10,833.3 | 1-6, 11,666.6
| +-------+-------+-------+-------+-------+-------
| .21 |100. |120. |108.33 |129.99 |116.66 |139.99
| .23 |109.52 |131.42 |118.65 |142.38 |127.77 |153.32
| .25 |119.04 |142.84 |128.96 |154.75 |138.88 |166.65
| .26 |123.8 |148.56 |134.12 |160.94 |144.44 |173.32
| .29 |138.09 |165.7 |149.6 |179.52 |161.11 |193.33
| .3125 |148.74 |178.56 |161.2 |193.44 |173.61 |208.23
| .33 |157.14 |188.56 |170.23 |204.27 |183.33 |219.99
| .35 |166.66 |199.99 |180.55 |216.66 |194.44 |233.32
| .375 |178.57 |214.28 |193.45 |232.14 |208.33 |249.99
----------+---------+-------+-------+-------+-------+-------+-------
| |45,000 Tensile |50,000 Tensile |55,000 Tensile
| | Strength. | Strength. | Strength.
| | 1-6, 7,500 | 1-6, 8,333.3 | 1-6, 9,166.6
| +-------+-------+-------+-------+-------+-------
48 Inches.| .21 | 65.62 | 78.74 | 72.91 | 87.49 | 80.2 | 96.24
| .23 | 71.87 | 86.24 | 79.85 | 95.82 | 87.84 |105.4
| .25 | 78.12 | 93.74 | 86.8 |104.16 | 95.48 |114.57
| .26 | 81.25 | 97.50 | 90.27 |108.32 | 99.3 |119.16
| .29 | 90.62 |108.74 |100.69 |120.82 |110.76 |132.91
| .3125 | 97.65 |117.18 |108.5 |130.2 |119.35 |143.22
| .33 |103.12 |123.74 |114.58 |137.49 |126.04 |151.24
| .35 |109.37 |131.24 |121.52 |145.82 |133.67 |160.4
| .375 |117.18 |140.61 |130.2 |156.24 |143.22 |171.86
+---------+-------+-------+-------+-------+-------+-------
| |60,000 Tensile |65,000 Tensile |70,000 Tensile
| | Strength. | Strength. | Strength.
| | 1-6, 10,000 | 1-6, 10,833.3 | 1-6, 11,666.6
| +-------+-------+-------+-------+-------+-------
| .21 | 87.49 |104.98 | 94.79 |113.74 |102.08 |122.49
| .23 | 95.83 |114.99 |103.81 |124.57 |111.8 |133.16
| .25 |104.16 |124.99 |112.84 |135.4 |121.52 |145.82
| .26 |108.33 |129.99 |117.36 |140.83 |126.38 |151.65
| .29 |120.83 |144.99 |130.9 |157.08 |140.97 |169.16
| .3125 |130.21 |156.25 |141.05 |169.26 |151.9 |182.28
| .33 |137.5 |165. |148.95 |178.74 |160.41 |192.49
| .35 |145.83 |174.99 |157.98 |189.57 |170.13 |204.14
| .375 |156.25 |187.50 |169.27 |203.12 |182.29 |218.74
----------+---------+-------+-------+-------+-------+-------+-------
| |45,000 Tensile |50,000 Tensile |55,000 Tensile
| | Strength. | Strength. | Strength.
| | 1-6, 7,500 | 1-6, 8,333.3 | 1-6, 9,166.6
| +-------+-------+-------+-------+-------+-------
54 Inches.| .21 | 58.33 | 69.99 | 64.81 | 77.77 | 71.29 | 85.54
| .23 | 63.88 | 76.65 | 70.98 | 85.17 | 78.08 | 93.69
| .25 | 69.44 | 83.32 | 77.16 | 92.52 | 84.87 |101.84
| .26 | 72.22 | 86.66 | 80.24 | 96.28 | 88.27 |105.92
| .29 | 80.55 | 96.66 | 89.5 |107.40 | 98.45 |118.14
| .3125 | 86.8 |104.16 | 96.44 |115.72 |106.09 |127.30
| .33 | 91.66 |109.99 |101.84 |122.22 |112.03 |134.43
| .35 | 97.22 |116.66 |108.02 |129.62 |118.82 |142.58
| .375 |104.16 |124.99 |115.74 |138.88 |127.31 |152.77
| +-------+-------+-------+-------+-------+-------
| |60,000 Tensile |65,000 Tensile |70,000 Tensile
| | Strength. | Strength. | Strength.
| | 1-6, 10,000 | 1-6, 10,833.3 | 1-6, 11,666.6
| +-------+-------+-------+-------+-------+-------
| .21 | 77.77 | 93.32 | 84.25 |101.1 | 90.74 |108.88
| .23 | 85.18 |102.21 | 92.28 |110.73 | 99.38 |119.25
| .25 | 92.59 |111.10 |100.3 |120.36 |108.02 |129.62
| .26 | 96.29 |115.54 |104.31 |125.17 |112.44 |134.8
| .29 |107.41 |128.88 |116.35 |139.62 |125.3 |150.36
| .3125 |115.55 |138.66 |125.38 |150.45 |135.03 |162.03
| .33 |122.22 |146.66 |132.4 |158.88 |142.59 |171.10
| .35 |129.69 |155.54 |140.43 |168.51 |151.23 |181.47
| .375 |138.88 |166.65 |150.46 |180.55 |162.03 |194.43
----------+---------+-------+-------+-------+-------+-------+-------
| |45,000 Tensile |50,000 Tensile |55,000 Tensile
| | Strength. | Strength. | Strength.
| | 1-6, 7,500 | 1-6, 8,333.3 | 1-6, 9,166.6
| +-------+-------+-------+-------+-------+-------
60 Inches.| .21 | 52.5 | 63. | 58.33 | 69.99 | 64.16 | 76.99
| .23 | 57.5 | 69. | 63.88 | 76.65 | 70.27 | 84.32
| .25 | 62.5 | 75. | 69.44 | 83.32 | 76.38 | 91.65
| .26 | 65. | 78. | 72.22 | 86.66 | 79.44 | 95.32
| .29 | 72.5 | 87. | 80.55 | 96.66 | 88.61 |106.33
| .3125 | 78.12 | 93.74 | 86.8 |104.16 | 95.48 |114.57
| .33 | 82.5 | 99. | 91.66 |109.99 |100.83 |120.99
| .35 | 87.5 |105. | 97.22 |116.66 |106.94 |128.32
| .375 | 93.75 |112.5 |104.16 |124.99 |114.58 |137.49
| +-------+-------+-------+-------+-------+-------
| |60,000 Tensile |65,000 Tensile |70,000 Tensile
| | Strength. | Strength. | Strength.
| | 1-6, 10,000 | 1-6, 10,833.3 | 1-6, 11,666.6
| +-------+-------+-------+-------+-------+-------
| .21 | 69.99 | 84. | 75.83 | 90.99 | 81.66 | 97.99
| .23 | 76.66 | 91.99 | 83.05 | 99.66 | 89.44 |107.32
| .25 | 83.83 | 99.99 | 90.27 |108.32 | 97.22 |116.66
| .26 | 86.66 |103.99 | 93.88 |112.65 |101.11 |121.33
| .29 | 96.66 |115.99 |104.72 |125.66 |112.77 |135.32
| .3125 |104.18 |124.99 |112.95 |135.54 |121.52 |145.82
| .33 |109.99 |132. |119.16 |142.99 |128.33 |153.99
| .35 |116.66 |139.99 |126.38 |151.65 |136.11 |163.33
| .375 |125. |150. |135.41 |162.49 |145.88 |174.99
----------+---------+-------+-------+-------+-------+-------+-------
| |45,000 Tensile |50,000 Tensile |55,000 Tensile
| | Strength. | Strength. | Strength.
| | 1-6, 7,500 | 1-6, 8,333.3 | 1-6, 9,166.6
| +-------+-------+-------+-------+-------+-------
66 Inches.| .1875 | 42.61 | 51.13 | 47.34 | 56.8 | 52.07 | 62.49
| .21 | 42.72 | 57.26 | 53. | 63.63 | 58.33 | 69.99
| .23 | 52.27 | 62.72 | 58. | 69.69 | 63.88 | 76.65
| .25 | 56.81 | 68.17 | 63.13 | 75.75 | 69.44 | 83.32
| .26 | 59.09 | 70.9 | 65.65 | 78.78 | 72.22 | 86.66
| .29 | 65.90 | 79.08 | 73.23 | 87.87 | 80.55 | 96.66
| .3125 | 71. | 85.2 | 78.91 | 94.69 | 86.89 |104.16
| .33 | 75. | 90. | 83.33 | 99.99 | 91.66 |109.99
| .35 | 79.56 | 95.47 | 88.38 |106.05 | 97.22 |116.66
| .375 | 85.22 |102.26 | 94.69 |113.62 |104.16 |124.99
| +-------+-------+-------+-------+-------+-------
| |60,000 Tensile |65,000 Tensile |70,000 Tensile
| | Strength. | Strength. | Strength.
| | 1-6, 10,000 | 1-6, 10,833.3 | 1-6, 11,666.6
| +-------+-------+-------+-------+-------+-------
| .1875 | 56.81 | 68.17 | 61.55 | 73.86 | 66.28 | 79.53
| .21 | 63.63 | 76.35 | 68.93 | 82.71 | 74.24 | 89.08
| .23 | 69.69 | 83.62 | 75.5 | 90.6 | 81.31 | 97.57
| .25 | 75.75 | 90.90 | 82.07 | 98.48 | 88.37 |106.04
| .26 | 78.78 | 94.53 | 85.35 |102.42 | 91.91 |110.29
| .29 | 87.87 |105.44 | 95.2 |114.24 |102.52 |123.02
| .3125 | 84.69 |113.62 |102.58 |123.09 |110.47 |132.56
| .33 | 99.99 |120. |108.33 |129.99 |116.66 |139.99
| .35 |106. |127.27 |114.89 |137.86 |123.73 |148.47
| .375 |113.62 |136.34 |123.1 |147.72 |132.57 |159.08
----------+---------+-------+-------+-------+-------+-------+-------
| |45,000 Tensile |50,000 Tensile |55,000 Tensile
| | Strength. | Strength. | Strength.
| | 1-6, 7,500 | 1-6, 8,333.3 | 1-6, 9,166.6
| +-------+-------+-------+-------+-------+-------
72 Inches.| .1875 | 39.06 | 46.87 | 43.4 | 52.08 | 47.74 | 57.28
| .21 | 43.75 | 52.5 | 48.6 | 58.33 | 53.47 | 64.16
| .23 | 47.91 | 57.49 | 53.24 | 63.88 | 58.56 | 70.27
| .25 | 52.08 | 62.49 | 57.87 | 69.44 | 63.65 | 76.38
| .26 | 54.16 | 64.99 | 60.18 | 72.22 | 66.2 | 79.44
| .29 | 60.41 | 72.49 | 67.12 | 80.55 | 73.84 | 88.60
| .3125 | 65.10 | 78.12 | 72.33 | 86.8 | 79.57 | 95.48
| .33 | 68.75 | 82.5 | 76.38 | 91.62 | 84.02 |100.82
| .35 | 72.91 | 87.49 | 81.01 | 97.21 | 89.11 |106.93
| .375 | 78.12 | 93.74 | 86.8 |104.16 | 95.48 |114.57
| +-------+-------+-------+-------+-------+-------
| |60,000 Tensile |65,000 Tensile |70,000 Tensile
| | Strength. | Strength. | Strength.
| | 1-6, 10,000 | 1-6, 10,833.3 | 1-6, 11,666.6
| +-------+-------+-------+-------+-------+-------
| .1875 | 52.08 | 62.49 | 56.42 | 67.70 | 60.76 | 72.91
| .21 | 53.33 | 69.99 | 63.19 | 75.82 | 68.06 | 81.66
| .23 | 53.88 | 76.65 | 66.21 | 83.05 | 74.58 | 89.43
| .25 | 69.44 | 83.32 | 75.22 | 90.26 | 81.01 | 97.21
| .26 | 72.22 | 86.66 | 78.24 | 93.88 | 84.25 |101.10
| .29 | 80.55 | 96.66 | 87.26 |104.71 | 93.98 |112.77
| .3125 | 86.8 |104.16 | 94.03 |112.88 |101.27 |121.52
| .33 | 91.66 |109.99 | 99.3 |119.16 |106.94 |128.32
| .35 | 97.22 |116.66 |105.32 |126.38 |113.42 |136.1
| .375 |104.16 |124.99 |112.84 |135.43 |121.52 |145.32
----------+---------+-------+-------+-------+-------+-------+-------
DEFINITION OF TERMS.
In the accompanying sections, some of the properties of iron and
steel, as employed in the construction of boilers, are given. It is,
therefore, desirable that the meanings applied to the various terms
used should be clearly understood. The definitions necessary are, then,
briefly as follows:—
=Tensile strength= is equivalent to the amount of force which, steadily
and slowly applied in a line with the axis of the test piece, just
overcomes the cohesion of the particles, and pulls it into separate
parts.
=Contraction of area= is the amount by which the area, at the point
where the specimen has broken, is reduced below what it was before any
strain or pulling force was applied.
=Elongation= is the amount to which the specimen stretches, between two
fixed points, due to a steady and slowly applied force, which pulls and
separates it into parts. Elongation is made up of two parts: one due to
the general stretch, more or less, over the length; the other, due to
contraction of area at about the point of fracture.
=Shearing strength= is equivalent to the force which, if steadily and
slowly applied at right angles, or nearly so, to the line of axis of
the rivet, causes it to separate into parts, which slide over each
other, the planes of the surface at the point of separation being at
right angles, or nearly so, to the axis of the rivet.
=Elastic limit= is the point where the addition to the permanent set
produced by each equal increment of load or force, steadily and slowly
applied, ceases to be fairly uniform, and is suddenly, after the point
is reached, increased in amount. It is expressed as a percentage of the
tensile strength.
=Tough.=—The material is said to be “tough” when it can be bent first
in one direction, then in the other, without fracturing. The greater
the angles it bends through (coupled with the number of times it
bends), the tougher it is.
=Ductile.=—The material is “ductile” when it can be extended by a
pulling or tensile force and remain extended after the force is
removed. The greater the permanent extension, the more ductile the
material.
=Elasticity= is that quality in a material by which, after being
stretched or compressed by force, it apparently regains its original
dimensions when the force is removed.
=Fatigued= is a term applied to the material when it has lost in
some degree its power of resistance to fracture, due to the repeated
application of forces, more particularly when the forces or strains
have varied considerable in amount.
=Malleable= is a term applied to the material when it can be extended
by hammering, rolling, or otherwise, without fracturing, and remains
extended. The more it can be extended without being fractured, the more
malleable it is.
=Weldable= is a term applied to the material if it can be united, when
hot, by hammering or pressing together the heated parts. The nearer the
properties of the material, after being welded, are to what they were
before being heated and welded, the more weldable it is.
=Cold-short= is a name given to the material when it cannot be worked
under the hammer or by rolling, or be bent when cold without cracking
at the edges. Such a material may be worked or bent when at a great
heat, but not at any temperature which is lower than about that
assigned to dull red.
=Hot-short= is when the material cannot be easily worked under the
hammer, or by rolling at a red-heat at any temperature which is higher
than about that assigned to a red-heat, without fracturing or cracking.
Such a material may be worked or bent at a less heat.
=Homogeneous= describes a material which is all of the same structure
and nature.
A homogeneous material is the best for boilers, and it should be of
suitable tensile strength with contraction of area and elongation
best suited for the purpose, having an elastic limit that will insure
the structure being reliable; it should be tough and ductile, and its
elasticity fairly good, and be capable of enduring strains without
becoming too quickly or easily fatigued. The material should be
malleable and in some cases weldable; that which is of a decidedly
cold-short or hot-short nature should be avoided.
BOILER REPAIRS.
[Illustration: Fig. 66.]
This cut represents a form of clamp used in holding the plates against
each other when being riveted.
[Illustration: Fig. 67.]
Fig. 67 represents a peculiar form of bolt for screwing a patch to
a boiler. It is threaded into the boiler plate, the chamfer rests
against the patch and the square is for the application of the
wrench. After the bolt is well in place, the head can be cut off with
a cold chisel.
REPAIRING CRACKS.
Cracks in the crown-sheet or side of a fire-box boiler, or top head
of the upright boiler can be temporarily repaired by a row of holes
drilled and tapped touching one another, with 3/8 or 1/2 inch copper
plugs or bolts, screwed into the plates and afterwards all hammered
together.
For a permanent job, cut out the defect and rivet on a patch. This had
better be put on the inside, so as to avoid a “pocket” for holding the
dirt. In putting on all patches, the defective part must be entirely
removed to the solid iron, especially when exposed to the fire.
NOTE.—When fire comes to two surfaces of any considerable extent, the
plate next to the fire becomes red-hot and weakens, hence the inside
plate, in repairs, must be removed.
The application of steel patches to iron boilers is injudicious. Steel
and iron differ structurally and in every other particular, and their
expansion and contraction under the influence of changing temperatures,
is such that trouble is sure to result from their combination.
DEFECTS AND NECESSARY REPAIRS.
[Illustration: Fig. 68.]
Fig. 68 represents a patch called a “spectacle piece.” This is used
to repair a crack situated between the tube ends. These are usually
caused (if the metal is not of bad quality) by allowing incrustation to
collect on the plate inside the boiler, or by opening the furnace and
smoke doors, thus allowing a current of cold air to contract the metal
of the plates round the heated and expanded tubes.
The “spectacle piece” is bored out to encircle the tubes adjacent
to the crack, or in other words, to be a duplicate of a portion of
the tube plate cracked. These plates are then pinned on to the tube
covering the crack.
Steam generators, as they are exposed to more or less of trying service
in steam production, develop almost an unending number and variety of
defects.
When a boiler is new and first set up it is supposed to be clean,
inside and out, but even one day’s service changes its condition;
sediment has collected within and soot and ashes without.
Unlike animals and plants they have no recuperative powers of their
own—whenever they become weakened at any point the natural course of
the defect is to become continually worse.
In nothing can an engineer better show his true fitness than in the
treatment of the beginnings of defects as they show themselves by
well-known signs of distress, such as leaks of water about the tube
ends, and in the boiler below the water line, or escaping steam above
it. In more serious cases, the professional services of a skillful and
honest boiler maker is the best for the occasion.
In a recent report given in by the Inspectors the following list of
defects in boilers coming under their observation was reported. The
items indicate the nature of the natural decay to which steam boilers
in active use are exposed. The added column under the heading of
“dangerous” carries its own lesson, urging the importance of vigilance
and skill on the part of the engineer in charge.
Nature of Defects. Whole Number. Dangerous.
Cases of deposit of sediment 419 36
Cases of incrustation and scale 596 44
Cases of internal grooving 25 16
Cases of internal corrosion 139 21
Cases of external corrosion 347 114
Broken and loose braces and stays 83 50
Settings defective 129 14
Furnaces out of shape 171 14
Fractured plates 181 84
Burned plates 93 31
Blistered plates 232 22
Cases of defective riveting 306 34
Defective heads 36 20
Serious leakage around tube ends 549 57
Serious leakage at seams 214 53
Defective water gauges 128 14
Defective blow-offs 45 9
Cases of deficiency of water 9 4
Safety-valves overloaded 22 7
Safety-valves defective in construction 41 16
Pressure-gauges defective 211 29
Boiler without pressure-gauges 3 0
This list covers nearly, if not all, _the points of danger_ against
which the vigilance of both engineer and fireman should be continually
on guard; and is worth constant study until thoroughly memorized.
NOTE.
Probably one-quarter, if not one-third, of all boiler-work is done
in the way of repairs, hence the advice of men who have had long
experience in the trade is the one safe thing to follow for the
avoidance of danger and greater losses, and for the best results the
united opinion of 1, the engineer, experienced in his own boiler and
2, the boiler-maker with his wider observation and 3, the owner of the
steam plant, all of whom are most interested.
Corrosion is a trouble from which few if any boilers escape. The
principal causes of external corrosion arise from undue exposure to
the weather, improper setting, or possibly damp brick work, leakage
consequent upon faulty construction, or negligence on the part of those
having them in charge.
Internal corrosion maybe divided into ordinary corroding, or rusting
and pitting. Ordinary corrosion is sometimes uniform through a large
portion of the boiler, but is often found in isolated patches which
have been difficult to account for. Pitting is still more capricious in
the location of its attack; it may be described as a series of holes
often running into each other in lines and patches, eaten into the
surface of the iron to a depth sometimes of one-quarter of an inch.
Pitting is the more dangerous form of corrosion, and the dangers are
increased when its existence is hidden beneath a coating of scale.
There is another form of decay in boilers known as grooving; it may
be described as surface cracking of iron, caused by its expansion and
contraction, under the influence of differing temperatures. It is
attributable generally to the too great rigidity of the parts of the
boiler affected, and it may be looked upon as resulting from faulty
construction.
[Illustration: Fig. 69.]
In plugging a leaky tube with a pine plug, make a small hole, of 3/16
of an inch diameter, or less, running through it from end to end. These
plugs should never have a taper of more than 1/8 of an inch to the
foot. It is well to have a few plugs always on hand. Fig. 69 exhibits
the best shape for the wooden plug.
QUESTIONS
BY THE PROPRIETOR TO THE ENGINEER IN CHARGE, RELATING TO CONDITION OF
THE BOILER,
How long since you were inside your boiler?
Were any of the braces slack?
Were any of the pins out of the braces?
Did all the braces ring alike?
Did not some of them sound like a fiddle-string?
Did you notice any scale on flues or crown sheet?
If you did, when do you intend to remove it?
Have you noticed any evidence of bulging in the fire-box plates?
Do you know of any leaky socket bolts?
Are any of the flange joints leaking?
Will your safety-valve blow off itself, or does it stick a little
sometimes?
Are there any globe valves between the safety-valve and the boiler?
They should be taken out at once, if there are.
Are there any defective plates anywhere about your boiler?
Is the boiler so set that you can inspect every part of it when
necessary?
If not, how can you tell in what condition the plates are?
Are not some of the lower courses of tubes or flues in your boiler
choked with soot or ashes?
Do you absolutely know, of your own knowledge, that your boiler is in
safe and economical working order, or do you merely suppose it is?
QUESTIONS
ASKED OF A CANDIDATE FOR A MARINE LICENSE RELATING TO DEFECTS IN BOILER
WITH ANSWERS.
If you find a thin plate, what would you do?
Put a patch on.
Would you put it on inside or outside?
Inside.
Why so?
Because the action that has weakened the plate will then act on
the patch, and when this is worn it can be replaced; but the plate
remains as we found it.
If the patch were put on the outside, the action would still be on
the plate, which would in time be worn through, then the pressure of
the steam would force the water between the plate and the patch, and
so corrode it; and during a jerk or extra pressure, the patch might
be blown off.
It is on the same principle that mud-hole doors are on the inside.
If you found several thin places, what would you do?
Patch each, and reduce the pressure.
If you found a blistered plate?
Put a patch on the fire side.
If you found a plate at the bottom buckled?
Put a stay through the centre of the buckle.
If you found several?
Stay each, and reduce the pressure.
The crown of the furnace down?
Put a stay through the middle, and a dog across the top.
If a length of the crown were down, put a series of stays and dogs.
A cracked plate?
Drill a hole at each end of the crack; caulk the crack, or put a
patch over it.
If the water in the boiler is suffered to get too low, what may be
the consequence?
Burn the top of the combustion chamber and the tubes; perhaps
cause an explosion.
If suffered to get too high?
Cause priming; perhaps cause the breaking of the cylinder covers.
THE INSPECTION OF STEAM BOILERS.
Let it be clearly understood that if there were no steam generators
using steam under pressure _there would he no boiler inspection, and no
licensing of engineers_; it requires no license to be a machinist or
a machine tender, no more would a license be essential to run a steam
engine, except it were connected with the boiler. _The danger to the
public arising from their use requires that the care and management of
high-pressure steam boilers shall be in hands of careful, experienced
and naturally ingenious men_, hence it is on the affairs of the Boiler
Room that the first tests are made, as to the worthiness of an aspirant
for an engineer’s license, hence, too, the success of many firemen in
obtaining the preference over engine-builders or school graduates, in
the line of promotion as steam engineers.
The inspection laws of the various states and cities are framed after
substantially the same leading ideas, and in presenting one the others
may be assumed to be nearly the same.
The special province of the Steam Boiler Inspection and Engineers’
Bureau in the police department in New York City is to inspect and test
all the steam boilers in the city, at certain stated periods, and to
examine every applicant for the position of engineer as to his ability
and qualifications for running an engine and boiler with safety.
According to the laws of the State, every owner, agent or lessee, of a
steam boiler or boilers, in the city of New York, shall annually report
to the board of police, the location of said boiler or boilers, and,
thereupon, the officers in command of the sanitary company shall detail
a practical engineer, who shall proceed to inspect such steam boiler or
boilers, and all apparatus and appliances connected therewith.
When a notice is received from any owner or agent that he has one or
more boilers for inspection, a printed blank is returned to him stating
that on the day named therein the boilers will be tested, and he is
asked to make full preparation for the inspection by complying with the
following rules:
Be ready to test at the above-named time.
Have boiler filled with water to safety-valve.
Have 1-1/4-inch connection.
Have steam gauge.
Steam allowed two-thirds amount of hydrostatic pressure.
More particularly stated, the following have been adopted by one or
more Inspection Companies:
HOW TO PREPARE FOR STEAM-BOILER INSPECTION.
1. Haul fires and all ashes from furnaces and ash pits.
2. If time will permit, allow boiler and settings to cool gradually
until there is no steam pressure, then allow water to run out of
boilers. It is best that steam pressure should not exceed ten pounds if
used to blow water out.
3. Inside of boiler should be washed and dried through manholes and
handholes by hose service and wiping.
4. Keep safety-valves and gauge-cocks open.
5. Take off manhole and handhole plates as soon as possible after
steam is out of boiler, that boiler may cool inside sufficiently for
examination; also _keep all doors shut_ about boilers and settings,
_except the furnace and ash-pit doors_. Keep _dampers_ open in _pipes_
and _chimneys_.
6. Have all ashes removed from under boilers, and fire surfaces of
shell and heads swept clean.
7. Have spare packing ready for use on manhole and handhole plates, if
the old packing is made useless in taking off or is burned. The boiler
attendant is to take off and replace these plates.
8. Keep all windows and doors to boiler room open, after fires are
hauled, so that boilers and settings may cool as quickly as possible.
9. Particular attention is called to Rule 5, respecting doors—which
should be open and which closed—also arrangement of damper. The
importance of cooling the inside of the boiler by removal of manhole
and handhole plates at the same time the outside is cooling, is in
equalizing the process of contraction.
ISSUING CERTIFICATES.
These conditions having been complied with, the boiler is thoroughly
tested, and if it is deemed capable of doing the work required of
it, a number by which it shall hereafter be known and designated is
placed upon it in accordance with the city ordinance: Failure to comply
with this provision is punishable by a fine of $25. A certificate of
inspection is then given to the owner, for which a fee of $2 is paid.
This certificate sets forth that on the day named the boiler therein
described was subject to a hydrostatic pressure of a certain number
of pounds to the square inch. The certificate tells where the boiler
was built, its style or character and “now appears to be in good
condition and safe to sustain a working pressure of —— to the square
inch. The safety-valve has been set to said pressure.” A duplicate of
this certificate is posted in full view in the boiler-room. In case
the boiler does not stand the test to which it is subject, it must be
immediately repaired and put in good working order before a certificate
will be issued.
THE HYDRAULIC TEST.
The hydraulic test is a very convenient method of testing _the
tightness of the work in a new boiler_, in conjunction with inspection
to a greater or lesser degree, in the passing of new work. As a
detector of leakages it has no rival, and its application enables
faulty caulking to be made good before the boiler has left the works,
and before a leak has time to enter on its insidious career of
corrosion. The extent to which it enables the soundness and quality of
the work to be ascertained is another matter, and depends on several
conditions. It will be evident that if the test be applied with this
object to a new boiler, the pressure should range to some point in
excess of the working load if such a test is to be of any practical
value.
What the excess should be so as to remain within safe limits cannot be
stated without regard being paid to the factor of safety adopted in the
structure.
In addition to the advantage which the hydraulic test affords as a
means of proving the tightness of the riveted seams and work generally,
it is also of frequent assistance in determining the sufficiency of
the staying of flat surfaces, especially when of indeterminate shape,
or when the stresses thrown upon them by the peculiar construction of
the boiler are of uncertain magnitude. For the hydraulic test, however,
to be of any real value in the special cases to which we refer, it is
essential that it should be conducted by an expert, and the application
of the pressure accompanied by careful gaugings, so as to enable the
amount of bulging and permanent set to be ascertained. Without such
readings the application of the test in such cases is worthless, and
may be delusive. Indeed, the careful gauging of a boiler as a record
of its behavior should be a condition of every test, and is a duty
requiring for its adequate performance a skilled inspector.
The duty of inspecting a new boiler or witnessing the hydraulic test
properly belongs to one of the regular inspecting companies, who have
men in their employ specially trained for the performance of such work.
The advantage accruing from such a course is well worth the fee charged
for the service, and secures a searching inspection of the workmanship,
which frequently brings to light defects and oversights that a mere
pumping-up of the boiler would never reveal. Such a proceeding in fact,
can only prove that the boiler is water-tight, and a boiler may be
tight under test although the workmanship is of the poorest character.
Besides, it is well to bear in mind that the tightness of a boiler
under test is no guarantee of its tightness after it is got to work.
In a word, as far as new boilers are concerned, the application of
hydraulic pressure unaccompanied by careful inspection and gaugings may
be almost worthless, while with these additions it may be extremely
valuable, especially in the case of boilers of peculiar shape, and is a
precaution that should not be neglected.
ENGINEERS’ EXAMINATIONS.
Keeping in mind the fact that _if there were no steam-boilers there
would be no examinations_ and no public necessity for licenses, these
“points” are added.
Examinations are trying periods with all engineers, as the best are
liable to fail in their answers from a nervous dread of the ordeal, but
the granting of the document is very largely influenced by the personal
experience of the candidate in the practical duties of the engine and
boiler-room, which must be stated and certified to by the evidence of
others.
_A general knowledge of the subject of steam engineering is the first
requisite to success._ A few sample questions are here given to show
the ordinary course pursued by examiners to determine the fitness of
applicants:
How long have you been employed as an engineer, and where? Are you
a mechanic? Where did you learn your trade? Give some idea of the
extent of your experience as an engineer? What kind of boilers have
you had charge of? Describe a horizontal tubular boiler. Describe a
locomotive style boiler. Describe a vertical style boiler. Describe
a sectional water tube boiler. How thick is the iron in the shell
of your boiler? How thick should it be in the shell of your boiler?
How thick are the heads in your boiler? How thick should they be in
your boiler? How are the heads fastened to the shell? What is the
best way to put heads in a boiler? How is the shell riveted? What
size rivets are used? What distance apart are they? How should the
shell be riveted? Why do they double rivet some seams? What ones
are best double riveted? How is a horizontal boiler braced? How is
a locomotive boiler braced? What is the size of and forms of braces
generally used? What is the size of your boiler or boilers, length
and diameter? How many have you in charge? Name the horse power. How
many tubes are in the boiler? What size are they, and how thick? How
long are they? How are they secured? What is the difference between a
socket and a stay bolt? What is the tensile strength of Boiler Iron?
What is the tensile strength of Boiler Steel? What is mild steel?
What is CH No. 1 Iron? What is Flange Iron? What is Hot Short and
Cold Short Iron? What is the common dimensions of a Man Hole? What is
it for? What are Hand Holes for? Do you open them often? How often?
What are Crown Bars and where are they used? How is a Boiler Caulked?
What is a Drift Pin?
MECHANICAL STOKERS.
In the back counties of England for many generations before the steam
engine was evolved from the brains of Trevithick, Watt and Stephenson,
the word “stoke” was used, meaning to “stir the fire.” The word was
derived from an ancient word, stoke, meaning a stick, stock or post.
To-day there are very many men who are called “stokers,” employed
principally on locomotive engines, steam vessels, etc., and then there
is the “stoke hole,” so-called, in which they do their work.
[Illustration: Mechanical Stoker]
But, now comes the “mechanical stoker,” which is well named, as its
office is to feed and “stir the fire” by a machine, thus relieving
the fireman from much excessively hard toil and allowing the time and
energy thus saved to be more profitably used elsewhere. The figure
shows a view of the American Stoker which is a device of the most
advanced type.
The principal parts of the machine are: 1, the Hopper, which may
be filled either by hand shoveling or by elevating and conveying
machinery; 2, the Conveyor Screw, which forces the coal, or indeed, any
description of fuel, forward to the 3, Magazine, shown in the figure
to the left; 4, a Driving Mechanism, which is a steam motor arranged
conveniently in front of the hopper; 5, the Retort, so called from its
being the place (above the conveyor) where the coal is distilled into
gas.
NOTE.—An illustrated printed description of this machine is issued and
sent free upon application by the makers. The American Stoker Co.,
Washington Life Building, Cor. Broadway and Liberty St., New York.
The rate of feeding coal is controlled by the speed of the motor, this
being effected by the simple means of throttling the steam in the
supply pipe to the motor. The shields covering the motor effectually
protect the mechanism from dirt and dust. The motor has a simple
reciprocating piston; its piston rod carries a crosshead, which, by
means of suitable connecting links, operates a rocker arm having a pawl
mechanism, which in turn actuates the ratchet wheel attached to the
conveyor shaft. The stoker is thus entirely self-contained and complete
in itself.
A screw conveyor or worm is located in the conveyor pipe and extends
the entire length of the magazine. Immediately beneath the conveyor
pipe is located the wind-box, having an opening beneath the hopper.
At this point is connected the piping for the air supply, furnished at
low pressure by a volume blower. The other end of the wind-box opens
into the air space between the magazine and outer casing. The upper
edge of the magazine is surrounded by tuyeres, or air blocks, these
being provided with openings for the discharge of air, inwardly and
outwardly.
The stoker rests on the front and rear bearing bars; the space between
the sides of the stoker and side walls is filled with iron plates,
termed “dead grates.” Steam is carried to the motor by a 3/4-inch steam
pipe. The exhaust steam from the motor is discharged into the ash pit.
In operation the coal is fed into the hopper, carried by the conveyor
into the magazine, which it fills, “overflows” on both sides, and
spreads upon the sides of the grates. The coal is fed slowly and
continuously, and, approaching the fire in its upward course, it is
slowly roasted and coked, and the gases released from it are taken up
by the fresh air entering through the tuyeres, which explodes these
gases and delivers the coal as coke on the grates above. The continuous
feeding gives a breathing motion to this coke bed, thus keeping it open
and free for the circulation of air.
It will be noted that in this machine the fuel is introduced from the
bottom of the bed of fuel, technically speaking, upon the principle of
“underfeeding.”
CHEMICAL TERMS
AND EXPLANATIONS RELATING TO FEED WATERS.
=_Chemistry_= is a science which investigates _the composition and
properties of material substances_.
Nature is composed of elementary elements; knowledge of these bodies,
of their mutual combinations, of the forces by which these combinations
are brought about, and the laws in accordance with which these forces
act, constitute chemistry, and the chemistry of steam engineering
largely deals with the foreign bodies contained in the feed water of
steam boilers.
=_Element._= In general, the word element is applied to any substance
which has as yet never been decomposed into constituents or transmuted
to any other substance, and which differs in some essential property
from every other known body. The term simple or _undecomposed
substance_ is often used synonymously with element.
There are about 70 _simple elements_, three-quarters of which are to
be met with only in minute quantities and are called rare elements.
Copper, silver, gold, iron, and sulphur are simple elements—_the metal
irridium, for example, is a rare element_—it is the metal which tips
the ends of gold pens—it is heavier than gold and much more valuable.
Probably there are not two tons of it in existence.
=_A Re-agent_= is a chemical used to investigate the qualities of some
other chemical—example, hydrochloric acid is a re-agent in finding
carbonic acid in limestone, or carbonate of lime, which when treated by
it will give up its free carbonic acid gas, which is the same as the
gas in soda water.
=_An Oxide_= is any element, such as iron, aluminium, lime, magnesia,
etc., combined with oxygen. To be an oxide _it must pass through the
state of oxidization_. Iron after it is rusted is the oxide of iron,
etc.
=_A Carbonate_= is an element, such as iron, sodium, etc., which forms
a union with carbonic acid—the latter is a mixture of carbon and
oxygen in the proportion of 1 part of carbon to 2 of oxygen. Carbonic
acid, as is well known, does not support combustion and is one of the
gases which come from perfect combustion. This acid, or what may be
better termed a gas, is plentifully distributed by nature and is found
principally combined with lime and magnesia, and in this state (_i.e._,
carbonate of lime and carbonate of magnesia) is one of the worst
enemies to a boiler.
=_An Acid_= is a liquid which contains both hydrogen and oxygen
combined with some simple element such as chlorine, sulphur, etc. It
will always turn blue litmus red, and has that peculiar taste known as
acidity; acids range in their power from the corrosive oil of vitriol
to the pleasant picric acid which gives its flavor to fruits.
=_Alkalies_= are the opposite to an acid; they are principally potash,
soda and ammonia—these combined with carbonic acid form carbonates.
Sal-soda is carbonate of soda.
=_A Chloride_= is an element combined with hydro chloric acid—common
salt is a good example of a chloride—being sodium united with the
element chlorine, which is the basis of hydro chloric acid. Chlorides
are not abundant in nature but all waters contain traces of them more
or less and they are not particularly dangerous to a boiler.
=_Sulphates_= are formed by the action of sulphuric acid (commercially
known as the oil of vitriol) upon an element, such as sodium, magnesia,
etc. The union of sodium and sulphuric acid is the well-known Glauber
salts—this is nothing more than sulphate of soda; _sulphate of lime is
nothing more than gypsum_. Sulphates are dangerous to boilers, if in
large quantities _should they give up their free acid_—the action of
the latter being to corrode the metal.
=_Silica_= is the gritty part of sand—it is also the basis of all
fibrous vegetable matter—a familiar example of this is _the ash_ which
shows in packing, which has been burnt by the heat in steam; by a
peculiar chemical treatment silica has been made into soluble glass—a
liquid. 65 per cent. of the earth’s crust is composed of silica—it
is the principal part of rock—pure white sand is silica itself—it is
composed of an element called _silicum_ combined with the oxygen of the
air. Owing to its abundance in nature and its peculiar solubility it is
found largely in all waters that come from the earth and is present in
all boiler scale.
In water analysis the term _insoluble matter_, is silica. This is one
of the least dangerous of all the impurities that are in feed water.
=_Magnesia_= is a fine, light, white powder, having neither taste nor
smell, almost insoluble in boiling, but less so in cold water. Magnesia
as found in feed water exists in two states, oxide and a carbonate,
when in the latter form and free from the traces of iron, tends to give
the yellow coloring matter to scale—in R. R. work, yellow scale is
called magnesia scale.
=_Carbonate of Magnesia_= is somewhat more soluble in cold than in hot
water, but still requires to dissolve it 9,000 parts of the latter and
2,493 of former.
Magnesia, in combination with silica, enters largely into the
composition of many rocks and minerals, such as soapstone, asbestos,
etc.
=_Lime_=, whose chemical name is _calcium_, is a white alkaline earthy
powder obtained from the native carbonates of lime, such as the
different calcerous stones and sea shells, by driving off the carbonic
acid in the process of calcination or burning.
Lime is procured on a large scale by burning the stone in furnaces
called kilns, either mixed with the fuel or exposed to the heated air
and flames that proceed from side fires through the central cavity of
the furnace in which the stones are collected.
The calcined stones may retain their original form or crumble in part
to powder; if protected from air and moisture they can afterwards be
preserved without change.
=_Soda_= is a grayish white solid, fusing at a red heat, volatile with
difficulty, and having an intense affinity for water, with which it
combines with great evolution of heat.
The only reagent which is available for distinguishing its salts from
those of the other alkalies is a solution of antimoniate of potash,
which gives a white precipitate even in diluted solutions.
=_Sodium_= _is the metallic base of soda._ It is silver white with
a high lustre; crystallizes in cubes; of the consistence of wax at
ordinary temperatures, and completely liquid at 194°, and volatilizes
at a bright red heat. It is very generally diffused throughout nature
though apparently somewhat less abundantly than potassium in the solid
crust of the globe.
=_Salt_=, the chloride of sodium, a natural compound of one atom of
chloride and one of sodium. It occurs as a rock inter-stratified with
marl, and sandstones, and gypsum, and as an element of salt springs,
sea water, and salt water lakes.
The proportions of its elements are 60.4 per cent. of chlorine and 39.6
per cent. of sodium.
In salt made of sea water the salts of magnesia with a little sulphate
of lime are the principal impurities.
The above mentioned chemical substances can be classified into two
distinct classes, _i.e._, incrusting and non-incrusting.
Of the incrusting salts, carbonate of magnesia is the most
objectionable, and any feed water that contains a dozen grains per
gallon of magnesia can be expected to have a most injurious effect on
the boiler, causing corrosion and pitting. Carbonate of lime, while not
as bad as the magnesia carbonate, yet has a very destructive action on
a boiler and 20 grains per gallon of this is considered bad water. All
silicates, oxides of iron, and aluminium, and sulphate of lime are also
incrusting. The non-incrusting substances are three, viz., chloride of
sodium (common salt), and sulphate and carbonate of soda.
NOTE.
In view of the increasing importance laid upon a knowledge of the
chemical formation of feed water, these chapters of Chemical Terms and
Analysis of Feed Waters are given to indicate _the direction in which
the advanced engineer must push his inquiries_. There are more millions
of treasure to be made by properly “treating” the water which enters
the steam generators of the world than can be extracted from its gold
mines.
An important “point” is to make sure, before adopting any permanent
system for purifying the waters of a steam plant, that it is always the
same in its ingredients, _i.e._, that the impurities contained in the
water are the same at all times.
ANALYSIS OF FEED WATER.
In response to a generous offer made by a leading engineering journal,
the following compositions of feed water were ascertained and
published. The “Directions” show how the water was forwarded, and the
tables, the result of careful examination, of samples sent from widely
separated sections of the country.
DIRECTIONS.
1. Get a clean gallon jug or bottle and a new cork (or, at all events,
a thoroughly clean one).
2. Wash out the vessel two or three times with the same water that is
going to be sent in it. This is to make sure that the sample may not be
contaminated with any “foreign” ingredient.
3. Tie the cork, after the bottle is filled with the water, with a
strong string or wire. Pack the bottle so secure, with hay or straw,
sawdust, or newspapers, that it may not knock itself to pieces against
the sides of the box.
FROM ARGOS, IND.
Grains per
Gallon.
Silica 1.1096
Oxides of iron and aluminium .1752
Carbonate of lime 11.9010
Carbonate of magnesia 5.4597
Carbonate of soda 1.1324
Chloride of sodium .0715
-------
Total solids 19.8494
FROM SIOUX FALLS, S. D.
Grains per
Gallon.
Silica .8292
Oxides of iron and aluminium .2452
Carbonate of lime 9.0699
Carbonate of magnesia 5.4376
Chloride of sodium 1.7172
Sulphate of sodium 4.5245
Sulphate of lime 2.6976
-------
Total solids 25.0936
FROM LITCHFIELD, ILL. Grains per
Gallon.
Silica .4711
Oxides of iron and aluminium .7475
Carbonate of lime .3800
Carbonate of magnesia 2.2911
Chloride of sodium 8.7543
Sulphate of soda 16.0329
Sulphate of lime 2.8168
-------
Total solids 31.4835
FROM CHELSEA, MASS. Grains per
Gallon.
Silica .1168
Oxides of iron and aluminium .6540
Carbonate of lime 34.5260
Carbonate of magnesia 22.8470
Chloride of sodium 63.2041
Sulphate of soda 28.4711
Carbonate of soda 32.2321
--------
Total solids 182.0511
FROM MEMPHIS, TENN. Grains per
Gallon.
Silica .8292
Oxides of iron and aluminium .4789
Carbonate of lime 1.8337
Carbonate of magnesia .9956
Carbonate of soda 1.9792
------
Total solids 6.1166
FROM PEKIN, ILL. Grains per
Gallon.
Silica 1.0628
Oxides of iron and aluminium Trace
Carbonate of lime 10.0915
Carbonate of magnesia 5.8224
Chloride of soda Trace
Sulphate of soda 1.2456
-------
Total solids 18.6471
FROM TIFFIN, OHIO. Grains per
Gallon.
Silica .5256
Oxides of iron and aluminium .2336
Carbonate of lime 12.6144
Carbonate of magnesia 10.2652
Carbonate of soda 2.4137
Sulphate of soda 6.8296
Chloride of sodium 1.0484
-------
Total solids 33.9395
CORROSION AND INCRUSTATION OF STEAM BOILERS.
No more perplexing question presents itself to the engineer and steam
user than the one to be inferred from the above heading. Enormous
losses of money, danger to life and property and the loss of position
and the reputation of the engineer are involved in it. How to avoid
these actual evils is of the first importance in steam economy. The
subject at first sight seems to the average student a difficult
one to master, but like all other matters pertaining to mechanics,
investigation that is backed with reason, will show that much that
appears obscure is really very plain indeed; this is because nature,
even down to the sediment remaining in a boiler after the conversion of
water into steam, operates in its formation with infinite exactness and
along well known lines.
Question.—What is corrosion?
Answer.—_Corrosion is simply rusting_ or the wasting away of the
surfaces of metals, for particulars of which see page 126.
Question.—What is incrustation?
Answer.—_Incrustation means_ simply _a coating over_.
Water, on becoming steam, is separated from the impurities which it
may have contained, and these form sediment and incrustation.
Boilers corrode _on the outside as well as within_, and to a great
extent unless carefully cleaned and painted; but it is the damage
caused by “hard” and acidulated water within the boiler that is to be
principally guarded against.
An extreme example of incrustation has been described in that of
a locomotive type of a stationary boiler. Its dimensions were:
seventy-two inches in diameter, twenty-two feet long, with 153
three-inch tubes; shell, three-eighths; head, three-eighths, and made
of iron. The scale against the back head was nearly two inches thick
and completely filled the space between the tubes, so that circulation
was impossible, the only wonder being that the boiler did not give out
sooner than it finally did. The scale was even with the top row of
tubes, the only part of the boiler generating steam being the fire box
and the upper row of tubes, the others acting simply as smoke conduits.
There was certainly a great loss of fuel, quite fifty per cent. Had
it been a horizontal boiler it would have burned out before the scale
became so heavy.
In the above instance, the loss in fuel is estimated at one-half.
Careful experiment has proved an average loss of fuel as follows:
1/16 inch of scale causes a loss of 13 per cent. of fuel.
1/4 inch of scale causes a loss of 38 per cent. of fuel.
1/2 inch of scale causes a loss of 60 per cent. of fuel.
It must be remembered that dry steam, as it is used through the engine
or for other purposes, _carries away none of the impurities_ which pass
with the water into the boiler; hence, in a battery of boilers burning,
say, 20 tons of coal per day and evaporating 10 lbs. of water to a
pound of coal, there is a body of water going through them every day of
200 tons. Multiply this by 300 days for a year = 60,000 tons, and it
will be seen how very great is the problem of keeping the interior of
the boilers free from scale and deposit.
Chemically pure water is that which has no impurities, and may be
described as colorless, tasteless, without smell, transparent, and in a
very slight degree compressible, and, were a quantity evaporated from a
perfectly clean vessel, there would be no solid matter remaining.
But, strangely, investigation has proved that water of this purity
rapidly corrodes iron, and attacks even pure iron and steel more
readily than “hard” water does, and sometimes gives a great deal of
trouble where the metal is not homogeneous. Marine boilers would be
rapidly ruined by pure distilled water if not previously “scaled” about
1/32 of an inch.
Water is formed by the union of two gases—oxygen and hydrogen. These
two are _simple bodies_, formed by the Creator in the beginning, which
are found _in combination_ in thousands of different forms. Both when
alone are invisible. Take one volume of oxygen and mix it with two
volumes of hydrogen and they will chemically unite and form water. This
is by measure. _By weight_ water is composed of 88.9 of oxygen to 11.1
of hydrogen = 100 parts. See pages 229, 230 for further information.
It is an important point to remember that when water is expanded about
1,700 times into steam, it is simply expanded water, as ice is hardened
water, _i.e._, in expanding into steam the two constituent gases do not
separate. Hence, in dealing with the impurities inside the boiler,
it is to be observed that in no sense do they change the essential
nature of water itself. The impurities are simply _foreign bodies_,
which have no legitimate place in the boiler, and are to be expelled
as dangerous foes. As a general principle, it may be stated that it is
more profitable to soften and filter the water used in boilers than to
trust to blowing out or dissolving the sediment and scale that will
be otherwise formed, for observations show that “anti-incrustators”
containing organic matter help rather than hinder incrustations, and
are therefore to be avoided. For the remedy of foul water there are
numerous contrivances to prevent it from entering the boiler, which
is far better than trying to extract the sediment after it is there,
though there are many ingenious methods for doing that also, some of
which will be detailed hereafter.
PRELIMINARY PRECIPITATION OF WATER.
A good method of avoiding incrustations in steam boilers is evidently
a preliminary purification of the feed-water, provided it can be done
by means sufficiently simple. This is a problem which it is claimed has
been solved by M. Dehne of Halle, by means of an arrangement which we
will herewith describe. The fresh water, which is taken up by a feed
pump, is sent into a heater where it is raised to a temperature that
will be favorable to chemical reaction. It then passes into a mixer
where it encounters certain reacting agents which have been pumped in
there by a pump of special design. These reacting agents are composed
of a mixture of carbonate of soda and of caustic soda, the carbonate
of soda serving to precipitate the sulphate of lime contained in the
feed water, while the caustic soda precipitates the carbonate of lime
and the magnesia. The relative dimensions between the special pump
and the feed pump are calculated in such a way that the proportions
of carbonate of soda and caustic soda in the mixture have always a
certain relation to the amount of lime and magnesia to be precipitated.
The water of the mixture is frequently very much disturbed by the
precipitations which are formed, and passes into a filter where all the
matters that are held in suspension are retained. It then goes into the
boiler. In cases where the feed-water is taken from a tank, the heater,
the mixer, and filter are put in the suction pipe of the feed pump, but
if, as often happens, the water is already under pressure and will pass
directly through the three, the feed pump will take the water directly
from the filter and pump it directly into the boiler.
A PRECIPITATOR FOR SEA WATER.
It is quite possible to prepare sea water in such a way as to
practically prevent any serious deposit forming from it.
The process employed is to add to the sea water a known quantity of
precipitator powder consisting chiefly of soda ash, and having done
this in a closed vessel, to heat the mixture by blowing into it waste
steam, until a pressure of from 5lbs. to 10lbs. is created; under these
circumstances practically all the magnesium and calcium salts separate
from the water and are easily got rid of by filtering it under pressure
into the hot-well.
A precipitator 6 ft. 4 in. high and 3 ft. in diameter, holds a ton of
water, and the time taken, from the first running the sea water in, to
its delivery into the hot-well, need not exceed 1 hour and 15 minutes,
so that in practice, giving plenty of time between the makes, it would
be perfectly easy to prepare 8 to 12 tons in the 24 hours with a small
precipitator of the size named. The prepared water has a density of
l/32nd, and may with safety be evaporated until its density is 5/32nds,
the salts present not crystalizing out until a density of from 6/32nds
to 7/32nds is reached.
In preparing sea water in the way proposed, every precaution must
be taken to add slightly less of the precipitant than is necessary
to entirely throw down the calcium and magnesium salts, as it is
manifestly impossible in practice to guard against small quantities of
sea water finding way into the boiler either from leaky condensers or
else being fed in by the engineer during some emergency, and if under
these conditions any excess of the precipitant were present in the
boiler, a bulky precipitate would be thrown down and cause trouble,
although it would not bind into a solid scale.
Briefly recapitulated the means which are best adapted for preventing
the formation of the dangerous organic and oily deposits considered are:
I. Filtration of condensed water through a coke column.
II. Free use of the scum cocks.
III. The use of water of considerable density rather than of fresh
water.
IV. The use of pure mineral oil lubricants in the smallest possible
quantity.
SCALE DEPOSITED IN MARINE BOILERS.
The analysis given below may be looked upon as typical of the
incrustation formed by fresh water, brackish water and sea water
respectively in marine boilers:
Constituent. River. Brackish. Sea.
Calcic carbonate 75.85 43.65 0.97
„ sulphate 3.68 34.78 85.53
Magnesic hydrate 2.56 4.34 3.39
Sodic chloride 0.45 0.56 2.79
Silica 7.66 7.52 1.10
Oxides of iron and alumina 2.96 3.44 0.32
Organic matter 3.64 1.55 trace
Moisture 3.20 4.16 5.90
------ ------ ------
100.00 100.00 100.00
From this it is evident we may look upon the incrustation from fresh
water as consisting of impure calcic carbonate, whilst that from sea
water is impure calcic sulphate, the brackish water from the mouths of
rivers yielding, as might be expected, an incrustation in which both
these compounds are present in nearly equal quantities.
The importance of these differences in the deposit formed is very
great, as it enables the shipowner to arrive at the conclusion as to
the treatment that the boilers have received during the voyage, by
examination and analysis of the scale that those boilers contain.
Taking, for instance, the case of a ship which uses fresh water
both for filling and make up, it is manifest that on her return to
port the scale should be very slight and should consist mainly of
calcic carbonate, whilst if the scale exceeds 1/16 in., and shows a
preponderance of calcic sulphate, it is manifest that such scale could
only have been formed by sea water, either leaking in from faulty
condensers or being deliberately fed into the boilers.
With the introduction of high pressure steam a new and dangerous form
of deposit has added to the trouble of the marine engineer; having
entered the boiler, the minute globules of oil, if in great quantity,
coalesce to form an oily scum on the surface of the water, or if
present in smaller quantities, remain as separate drops; but show no
tendency to sink, as they are lighter than water.
Slowly, however, they come in contact with small particles of other
solids separating from the water and sticking to them, they gradually
coat the particles with a covering of oil, which in time enables
the particles to cling together or to the surfaces which they come
in contact with. These solid particles of calcic carbonate, calcic
sulphate, etc., are heavier than the water, and, as the oil becomes
more and more loaded with them, a point is reached at which they have
the same specific gravity as the water, and then the particles rise
and fall with the convection currents which are going on in the water,
and stick to any surface with which they come in contact, in this way
depositing themselves, not as in common boiler incrustation, where they
are chiefly on the upper surfaces, but quite as much on the under sides
of the tubes as on top.
The deposit so formed is a wonderful non-conductor of heat, and also
from its oily surface tends to prevent intimate contact between
itself and the water. On the crown of the furnaces this soon leads to
overheating of the plates, and the deposit begins to decompose by heat,
the lower layer in contact with the hot plates giving off various gases
which blow the greasy layer, ordinarily only 1/64 inch in thickness, up
to a spongy leathery mass often 1/3 inch thick, which, because of its
porosity is an even better non-conductor of heat than before, and the
plate becomes heated to redness.
When water attains a temperature, as it does under increasing pressure,
ranging from 175° to about 420° Fahr., all carbonates, sulphates and
chlorides are deposited in the following order:
First. Carbonate of lime at 176° and 248° Fahr.
Second. Sulphate of lime at 248° and 420°.
Third. Magnesia, or chlorides of magnesium, at 324° and 364°.
It is to take advantage of this fact that mechanically arranged jets,
sprinklers and long perforated pipes are introduced into the interior
of the boiler; these tend to scatter the depositing impurities and also
to bring the feed water more quickly to the highest heat possible.
With regard to the oxide of iron or iron salts in solution, these can
best be treated with small quantities of lime. By adding re-agents,
they set up chemical changes, which result in precipitation, which
give the water a milky appearance; they divide into particles, and
ultimately settle, leaving the water pure and bright. The mechanical
treatment on a limited scale would be easy, a settling tank sufficing;
but this becomes a different matter when large quantities have to be
dealt with.
ANALYSIS OF AVERAGE BOILER SCALE.
Parts per 100 parts
of deposit.
Silica .042 parts.
Oxides of iron and aluminium .044 „
Carbonate of lime 30.780 „
Carbonate of magnesia 51.733 „
Sulphate of soda Trace „
Chloride of sodium Trace „
Carbonate of soda 9.341 „
Organic matter 8.060 „
--------------
Total solids 100. Parts
The percentage only of each ingredient the scale is composed of is
given, as it cannot be told how much water was evaporated to leave this
amount of solid matter.
A LOCOMOTIVE-BOILER COMPOUND.
The lines of a certain great R. R. traverse a country where the
water is very hard and they are compelled to resort to some method
of precipitating the lime that is held in solution. After many tests
and experiments they have made a compound and use it as follows: in
a barrel of water of a capacity of fifty gallons they put 21 lbs. of
carbonate of soda, or best white soda ash of commerce, and 35 lbs. of
white caustic soda. The cost, per gallon, is about 2-1/2 cents.
The compound is carried in this concentrated form, in calomine cans
on the tender of each locomotive. A certain amount, according to the
necessities of the case, is poured into the tender at the water tank
at each filling. This amount is determined by analysis, and varies all
the way from two to fifteen pints to two thousand gallons of water.
The precipitating power of this compound may be taken roughly at 2/3
of a pound of the carbonate of lime, or equivalent amount of other
material, per pint of the compound. On their western lines where they
are dealing with alkali waters and those containing sulphates, the
company use merely 60 pounds of soda ash to a barrel of water. When the
water is pumped into the boiler the heat completes the precipitation
and aggregation of the particles, and this does away with all trouble
of the tenders or injector tubes clogging up.
The case is an interesting one to stationary engineers, because where
the water is pumped into the boiler from tanks the same compound
can be used, provided the water contains the proper constituents to
be precipitated by it; and where the water is taken from city water
mains, it would be a simple matter to devise an apparatus to admit the
compound to the feed pipes.
“POINTS” RELATING TO THE SCALING OF STEAM BOILERS.
The peculiarity about the sulphate of lime is that _the colder the
water the more of it will be held in solution_. Water of ordinary
temperature may hold as high as 7 per cent. of lime sulphate in
solution, but when the temperature of the water is raised to the
boiling point a portion of it is precipitated, leaving about .5 of one
per cent. still in solution. Then as the temperature of the water is
raised, still more of the substance is precipitated and this continues
until a gauge pressure of 41 pounds has been reached which gives a
temperature of about 200 degrees; at this point all the sulphate of
lime has been precipitated. Many other scale forming substances act in
a similar manner. This shows quite plainly that any temperature that
can be produced by the use of exhaust steam would not be sufficient to
cause the precipitation of all the substances which might be contained
in the water.
That boiler incrustations are the immediate causes of the majority of
steam boiler explosions is no longer a doubtable question.
Nearly all foreign matter held in solution in water, on first becoming
separated by boiling, _rises to the top in the form of what is commonly
called scum_, in which condition much of it may be removed by the
surface blow-off. If not removed, however, the heavier particles will
be attracted to each other until they have become sufficiently dense to
fall to the bottom, where they will be deposited in the form of scale,
covering the whole internal surface of the boiler below the water line,
with a more or less perfect non-conductor of heat.
It is recorded that the engineer of the French ocean steamer _St.
Laurent_ omitted to remove a bar of zinc when repairing and cleaning
out his boilers. On opening the boilers at the end of the voyage to his
great surprise he found that the zinc had disappeared, but his boilers
were entirely free from scale and the boiler plates not injured in the
least.
It has been recently determined by some German experimenters that
sugar effects a strong action upon boilers. It has an acid reaction
upon the iron which dissolves it with a disengagement of hydrogen. The
amount of damage done increases with the amount of sugar in the water.
These results are worthy of note in sugar refineries and places where
sugar sometimes finds its way into the boilers by means of the water
supplied. The experimenters in question also find that zinc is strongly
attacked by sugar; copper, tin, lead and aluminium are not attacked.
Two reasons, relating to incrustations, for not blowing out a boiler
while under steam pressure may be given as follows: One is, that the
foreign matter floating on top of the water will be deposited on the
shell of the boiler as the water gradually subsides, and, second,
the heated walls of the furnace will communicate a sufficiently high
temperature to the boiler to dry and flake the sediment that would
otherwise remain in the boiler in the shape of mud, which could easily
be washed out were it not for the baking process.
Bark, such as is used by tanners, has an excellent effect on boiler
incrustations. It may be used as follows: Throw into the tank or
reservoir from which the boilers are fed a quantity of bark in the
piece, in sufficient quantity to turn the water to a light brown
color. Repeat this operation every month at least, using only half
the quantity after the first month. Add a very small quantity of the
muriate of ammonia, about one pound for every 2,000 gallons of water
used. This will have the effect of softening as well as disintegrating
_the carbonate of lime_ and other impurities deposited by the action of
evaporation.
NOTE.—Care must be exercised in keeping the bark, as it becomes broken
up, from the pump valves and blow-off valves. This may be accomplished
by _throwing it into the reservoir confined in a sack_.
Among the best samples of boiler compounds ever sent to the laboratory
for analysis was found to be composed of:
Pounds
Sal soda 40
Catechu 5
Sal ammoniac 5
This solution was formerly sold at a good round figure, but since its
nature became more generally known, it is not found in market, but is
largely used, consumers putting it up in lots sufficient to last a year
or so at a time.
The above is strongly recommended by those who have used it, _one pound
of the mixture being added to each barrel of water used_ but after the
scale is once thoroughly removed from the boiler, the use of sal soda
alone is all that is necessary. By the use of ten pounds per week a
boiler 26 feet long and 40 inches in diameter in one of the iron mills
of New Albany, Ind., has been kept clean of scale equal to a new boiler.
There are other evils sometimes inherent in hard waters over and above
the mere production of a crust. Some waters contain a great deal of
soluble magnesia salts, together with common salt. When this is the
case there is a great chance of corrosion, for the former is acted on
by steam at high pressure in such a way that muriatic acid fumes are
produced, which seriously corrodes the boiler, and, what is far worse,
passes with the steam into the engine, and produces corrosion in the
cylinders and other delicate fittings into contact with which the
steam passes. All this can, however, be obviated by the removal of the
magnesia from the water.
There has not been, and never can be, made a mechanical device which
will precipitate all the ingredients contained in a water taken from
a natural source of supply, and if it were possible to do so it would
be the most ruinous thing one could do for the boilers, as water is
the greatest _solvent_ known to chemistry, and its nature is to hold
in solution and be impregnated with the different elements it comes in
contact with, to a certain per cent., and if its lime, magnesia, and
the mineral salts are taken away, and the pure water is pumped into
the boilers, it will take up the iron, causing pitting and grooving of
the boilers. It is better to let nature take its course, to a certain
extent, and neutralize what little mineral deposit forms in the boilers
with as small an amount of vegetable matter as possible.
It is well to note that different waters require different treatment;
what will be of benefit in one instance will be of no value whatever in
a different water, many of the “compounds” sold to prevent and remove
scale will certainly destroy a boiler if they are used persistently,
because they are composed of the exact opposite chemicals which should
be used; as an example it is stated that at one establishment one
thousand dollars were expended annually for a mixture which it is said
resulted in the reduction of the life and usefulness of the boilers of
50 per cent.
ENGINEERS’ TESTS
FOR IMPURITIES IN FEED WATER.
Much expense can be saved in fuel and boiler repairs by a little
preliminary expenditure of money in securing a supply of good water
for the steam boilers of a new establishment. Well water is nearly
always inferior to the running water of streams; water from mines is
especially hurtful, containing, as they do, large quantities of free
sulphuric acid. Wells along the sea shore or on the banks of rivers
affected by the tides, are likely to be saturated with chloride of
magnesium. It is in determining these points that these ready tests of
feed water are most useful.
A thorough and really scientific analysis of feed water is a costly
and tedious process, but _a simple and perhaps sufficiently accurate
test_ may be made as follows: take a large (or tall) clear glass vessel
and fill it with the water to be tested; add a few drops of water of
ammonia, until the water is distinctly alkaline; next add a little
phosphate of soda; the action of this is to change the lime, magnesia,
etc., into phosphates, in which form they are deposited in the bottom
of the glass. The amount of the matter thus collected gives a crude
idea of the relative quality of sediment and scale-making material in
the water.
Water turning _blue litmus paper red_, before boiling, contains an
acid, and if the blue color _can be restored by heating_, the water
contains carbonic acid. Litmus paper is sold by druggists.
If the water has a foul odor, giving a black precipitate with acetate
of lead, it is sulphurous.
An experiment may be tried by dissolving common white or other pure
soap in a glass of water, and then stirring into the glasses of water
to be tested a few teaspoonsful of the solution; the matter which will
be deposited will show the comparative amount of the scale-making
material contained in the feed water.
_In order to ascertain the proportion of soda to the feed water the
following method is recommended_:
1. Add 1/16th part of an ounce of the soda to a gallon of the feed
water _and boil it_. 2. When the sediment thrown down by the boiling
has settled to the bottom of the kettle, pour the clear water off, and
3, add 1/2 drachm of soda. Now, if the water remains clear, the soda,
which was first put in, has removed the lime, but if it becomes muddy,
the second addition of soda is necessary.
In this way a sufficiently accurate estimate of the quantity of soda
required to eliminate the impurities of the feed water can be made and
the due proportion added to the feed water.
By exercising a little judgment, the use of pure chemicals, with
well cleaned vessels, test tubes, etc., the following reagents will
determine the character of the most important elements which injure the
iron surfaces of a steam boiler.
Carbonic acid is indicated by baryta water.
Sulphates are indicated by chloride of barium.
Chlorides are indicated by nitrate of silver.
Lime salts are indicated by oxalate of ammonia.
Organic matter is indicated by chloride of mercury.
The “base” of the better class of the various patented boiler compounds
is tannin (whence tannic acid) and some form of alkali, and if the
compounds were to be deprived of these two elements they would be
absolutely worthless.
Where they contain, as some certainly do, sal-ammoniac, muriatic,
hydrochloric and sulphuric acids, they cannot but act as boiler
destroying agents.
Tannin or tannic acid is the principal ingredient used in preparing
leather. It is found in a great variety of plants—sassafras root has
it in large proportion, the gall nut and the bark of various trees,
especially the oak produce it.
It is the presence of this acid that gives their only value to very
many “compounds,” tan bark, gum catechu (which sometimes contains
one-half part of tannic acid), etc. The acid seems to have but little
effect where large quantities of sulphate of lime are present, but in
waters where carbonate of lime predominates its detersive qualities are
more marked.
The records of the Patent Office show that one boiler compound
_contains 23 per cent. of catechu_, and others, 60, 81, 5,
respectively, by which may be inferred the large quantity of this
agent, which has been sold in combination with other chemicals,
principally soda.
NOTE.
While the product of water steeped in clean tan bark may be favorable
in its action upon boiler incrustation, _it has been found to be very
unsafe, in practice, to use the “tan liquor” taken from the vats_.
The danger arises from the fact that sometimes during the process of
tanning leather, the required acidity cannot be produced by natural
fermentation when sulphuric acid is added, in order to bring the liquor
to its required strength—in due course, this corrosive substance acts
injuriously on the boiler.
USE OF PETROLEUM OIL IN BOILERS.
The use of crude (unrefined) mineral oil in steam boilers is attended
by risks caused by impurities and foreign substances mixed with it.
These are likely to combine with the earthy matter in the water and
tend to form instead of preventing scale; the tar and wax contained in
crude petroleum combine with the sediment in steam boilers, and the
paste prevents the water from reaching and protecting the plates. This
is true particularly in shell boilers which have flat surfaces over the
fire. Refined mineral oil has none of these disadvantages.
Kerosene oil has all the advantages to be derived from the use of crude
petroleum and the above objections quite removed.
In one system of the application of steam the use of kerosene and
petroleum cannot be recommended: that is _when live steam is used for
cooking purposes_, the odor from the oil will impregnate the meat and
other products designed for food consumption.
KEROSENE OIL IN BOILERS.
Under certain conditions, and with care and judgment, the use of
refined petroleum has been found to be of great advantage in removing
and preventing scaling in steam boilers.
There is no well authenticated case where a systematic, regular and
uniform feed of pure kerosene oil to a steam boiler has failed to
operate beneficially upon the scale formation.
The best results are obtained by the use of the oil _under the same
arrangement that cylinder oil is fed to an engine_. The kerosene is
sometimes introduced through a one-fourth inch branch to the suction
pipe of the feed pump, leading to the vessel containing the oil,
so that any quantity, large or small, can be put into the boiler
simultaneously with the usual feed. The drawback to this arrangement
is that when the feed water heater has to be cleaned, a gallon or more
of the oil is often lost, which together with a very unpleasant odor,
when used in this manner, tends to condemn its use. _But when piped
between the boiler and heater_, these objections cease. We present an
arrangement which is illustrated by cut on page 157.
This is nothing more than a storage system with sight feed, by use of
which the oil can be fed drop by drop as desired—for each drop of water
entering the reservoir a drop of oil is forced down the small 1/4-in.
pipe, up the glass tube and on into the boiler.
In piping it is necessary to have the water or larger pipe (1/2 in.)
attached through the lower plug as shown in cut, and the oil as shown,
going through the smaller or 1/4-in. pipe—_i.e._, the oil pipe must,
under all circumstances, be the smaller of the two.
In the figure is shown a piece of 6-in. gaspipe, about a foot in
length, plugged at each end; the top plug has one opening, for an
inch nipple “a” with top. This opening is to be used in filling the
reservoir with oil. The bottom plug has two holes, one for the 1/2-inch
water pipe, and the second for a small pet cock “B,” to let the water
out, whenever it is necessary to refill the tank with kerosene. The
water gauge connection is the ordinary, cheap brass fixture, with
boxes, nipples, etc., used in boilers, with gasket of rubber bottom
and top of the glass. The glass plainly exhibits the depth of water
and oil in the reservoir as well as the feed of minute drops of oil as
they speed on their beneficent mission softening the injurious scale.
There are the usual 2 valves on the water glass; by opening the lower
one more or less, the amount of oil used can be regulated to a nicety.
The valves can be used to entirely cut off the apparatus at any time
desired.
[Illustration: METHOD OF FEEDING KEROSENE OIL TO BOILER.—Fig. 69.]
NOTE.—Should the end of the screw connection inside the holder which
each one of these valves control, not be 1/4 inch, a reduced elbow
should be used, as 1/4-in. pipe will give the best satisfaction when
used as a stand pipe inside the reservoir.
The quantity of oil to be fed to a boiler is very largely to be
determined by experiment commencing with a minimum and increasing the
amount as found necessary to keep down the scale formation. The use
of 2 qts. of the oil per week has been found to be sufficient for a
boiler 4 feet in diameter and 12 feet long, and three quarts per week
on boilers 5 feet in diameter. This quantity may be regarded as the
smallest advisable to use and from that up to 1 to 2 gallons per diem
in boilers, say of 125 horse power, when pushed to their capacity in
evaporating water.
The result of careful experiments justifies the use of kerosene, the
scale being less than in four years’ previous experience, and a large
portion of the boiler showing the clean black steel, in as apparently
good condition as when new.
Despite the small quantity of kerosene used in the boilers in this
case, the odor was perceptible by opening an air valve to any steam
radiator in any of the buildings. When as much as a gallon per week was
used, the odor was very strong, but with one half that amount it was
hardly perceptible, and only to be noticed when an air valve had been
open a long time. And since commencing to use the oil a much greater
deposit of rust scales than usual has been found in the various steam
traps in the buildings, indicating that the oil is also exerting a
cleansing influence on the pipes of the whole system.
NOTE.—Provision must be made for the removal of the scale as it drops
from the internal surfaces of the boiler, as at times many bushels of
it have been deposited directly over the furnace; hence, if a boiler
is known to be badly incrusted, the kerosene should not be put in the
first time more than three days before it is intended to wash the
boiler.
NOTE 2.—The safety valve should be opened to allow the escape of the
gas arising from the kerosene before cleaning out the boiler; where a
lighted lamp or candle is used, as it must necessarily be—indeed this
is a precaution which ought always to be observed in all cases, viz.,
properly to ventilate boilers, heaters, and tanks of all descriptions
before entering them with lighted lamps and torches. While these gases
are not likely to cause an explosion, they burn quite rapidly and
should be promptly removed without giving opportunity for an accident.
The accumulation of gas is not confined to the use of kerosene oil for
the prevention of scale in steam boilers, but is also found in flour
mills, confectioners’, conduits for electric wires, brewers’ vats,
etc. So, with common sense precautions, no extra risk is run in using
kerosene oil in steam boilers.
MECHANICAL BOILER CLEANERS.
Owing to the fact (1) that nearly, if not quite all, the impurities
which exist in feed water are set free by a high temperature attained
under pressure; (2) that these impurities are left in the boiler by
the constant use of the steam, there follows the result that the water
remaining is more and more impregnated with the residuum composed of
the foreign matters which (the water removed) constitutes mud, scale,
etc.
The custom has been and is now to regularly “blow off” one or two
gauges of this water once or twice per day replacing it with fresh
water of less density; that this is a very imperfect method for
removing the foreign matter is readily allowed, besides wasting
absolutely all the units of heat contained in the water blown off.
Now, within the boiler while in use, under the operation of the fierce
heat of the furnaces, are constant changes in the position of the
water caused by the boiling, by the withdrawal of the steam and by the
constant effort of the hot water to rise and the cold water to fall.
The water thus keeps in circulation everything within the boiler,
including the sediment, _except in places where the water is from
any cause without motion_. In these quiet nooks there is a constant
depositing of the elsewhere active foreign matters contained in the
water, which deposits, in the form of mud and scale, left undisturbed,
causes loss and danger.
It is in taking advantage of these facts, and of the principles of the
circulation of hot and cold water, that mechanical boiler cleaners are
brought into successful use.
These devices for the stilling of the water and collection of the
sediment are made in various forms and all sizes and capacities, and
are located at the sides or back of the boiler setting and even on top
of the boiler. There is a system where pipes in a coil are fixed in
the sides of the furnace and exposed to its greatest heat, and which,
owing to their enlarged area, act as most efficient reservoirs. In
all these devices there is an _upflow pipe_ connected with the lower
and coolest water, and a _return pipe_ connecting with the top of the
water where it is hottest. This arrangement assures a constant current
which is more or less rapid according to the intensity of the fire and
which keeps up as long as the firing is done. Where this current passes
through the reservoir, the enlarged area and comparative quiet is
favorable for the deposit of the sediment and in practical experience
it does deposit nearly all of it. The collection of the impurities is
helped by a _funnel-shaped appliance_ placed at the opening of the
upflow pipe, which, aided by the rapid flow of the hot water, carries
the floating scum towards it into the reservoir. Attached to the
reservoir is the blow-off pipe through which the deposited matter is
removed as often as necessary.
The use of these mechanical cleaners is readily understood: (1) they
provide a place of accumulation for the sediment; (2) they save the
necessity of opening the boilers to remove by hand, the refuse of the
boiler; (3) save fuel by avoiding the necessity of frequent blowing off
one or two gauges of water, and (4) by the preventing the formation of
scale with its attendant evils.
SCUMMING APPARATUS.
In addition to the bottom blow-out apparatus every boiler should be
provided with means for blowing out water from the surface in order
to remove the fine particles of foreign matter floating there, which
afterward settle and consolidate as scale on the heating surfaces.
[Illustration: Fig. 70.
_Scum Cock_]
It consists, in its simplest form, of a pan, or a conical scoop, near
the surface of the water, but below it, connected with a pipe passing
through the boiler-shell, on which is a cock, or valve, for regulating
the escape of the water laden with the impurities deposited in the pan.
There are patented apparatus for this purpose which are well designed
and easily fitted to a boiler.
The office of the surface blow-off, illustrated in Fig. 70, is to
remove the foreign matter which is precipitated from its solution in
the water.
A surface blow-off used occasionally will remove the greater portion
of this scum and keep the boilers reasonably free from scale and mud.
Where dirty or muddy water is fed into the boilers the surface blow-off
is one of the cheapest and most efficient means for keeping the boiler
clean. The efficiency of the surface blow-off is not so great as that
of some of the mechanical boiler-cleaners, as by their use it is not
required that any hot water shall be wasted, and this is the greatest
objection to the surface blow-off, as in the hands of some people a
large amount of boiling water is wasted each time it is used. But
both of these arrangements are virtually skimmers, as they remove the
precipitated mineral and vegetable matter from the surface of the water
in the boiler. One does it by blowing out the scum and some water at
the same time, while the mechanical boiler-cleaner removes the scum,
but returns the water to the boiler.
There are several efficient ways of arranging a surface blow-off. The
principal part of the blow-off is a pan or perforated pipe placed
horizontally at the water level having a pipe leading outside the
boiler to any convenient place where the scum may be blown. When a
perforated pipe is used the action is to force the scum from the top of
the water during the time the valve is open, and blow it through the
pipe. In using an apparatus of this kind it should be blown often, but
only for a moment at a time, as all the scum near the pipe is removed
immediately, and to keep the valve open longer than necessary to remove
the scum near the pipe would allow the escape of clean water or steam
which would be wasteful. If a pan is used and is fastened so that the
top is secured at the ordinary water level, as shown in Fig. 70, the
blow-off pipe leading from near the bottom of the pan, it will be more
efficient than the perforated pipe arrangement as it will not require
to be used so often, and the waste of water and steam will not be so
great. The pan, by producing an eddy in the water, causes all the
scum to gather over the top, and as the water is quiet there it will
gradually settle into the pan, where it will remain as mud. When the
blow-off valve is opened the greater part of the mud which is gathered
is blown out, and but very little water is carried with it.
USE OF ZINC IN MARINE BOILERS.
Zinc has been used in marine boilers for many years, but it was not
until the publication in 1880 of the report of the Admiralty committee
that the use of zinc became general. It has been used in various ways:
1.—Virgin spelter, as imported in oblong slabs of various sizes.
2.—Cast, or remelted zinc. 3.—Cast zinc buttons, generally made from
virgin spelter or new clean zinc trimmings. 4.—Zinc spheres. 5.—Rolled
zinc blocks, generally 12 inches by 6 inches, and thicknesses varying
from 1/4 inch to 1-1/2 inch, generally with a 13/16-inch hole in the
centre.
It is desirable that close-grained zinc of uniform structure and free
from impurities should be used, and rolled zinc appears to meet this
want. The wear is entirely confined to the surface. It does not appear
to become distorted or broken up. On the contrary, it gradually wastes
away till only a slight shred, a sort of skeleton frame work, remains
to indicate what it has been.
The primary object in the use of zinc in boilers is the prevention
of corrosion, but it has also some effect in reducing the amount of
incrustation, and rendering it softer and less adherent.
TABLE
_Showing Amount of Sediment collecting in a steam boiler when
evaporating 6,000 gallons per week, of 58,318 grains each._
-----------------------+--------------------
When a gallon of feed |
water evaporated to |The amount of solid
dryness at 212 degrees | matter collecting
Fahrenheit, leaves of |in boiler per week
solid matter in grains:| will be:
-----------------------+---------+----------
Grains. | Pounds. | Ounces.
1 | | 13.714
2 | 1 | 11.428
3 | 2 | 9.143
4 | 3 | 6.857
5 | 4 | 4.571
6 | 5 | 2.285
7 | 6 |
8 | 6 | 13.714
9 | 7 | 11.428
10 | 8 | 9.142
15 | 12 | 13.713
20 | 17 | 2.284
25 | 21 | 6.855
30 | 25 | 11.426
35 | 30 |
40 | 34 | 4.571
45 | 38 | 9.143
50 | 42 | 13.714
55 | 47 | 2.285
60 | 51 | 6.857
65 | 55 | 11.428
70 | 60 |
75 | 64 | 4.571
80 | 68 | 9.143
85 | 72 | 13.714
90 | 77 | 2.285
95 | 81 | 6.857
100 | 85 | 11.428
110 | 94 | 4.571
120 | 102 | 13.714
130 | 111 | 6.857
140 | 120 |
150 | 128 | 9.142
160 | 137 | 2.285
170 | 145 | 11.428
180 | 154 | 4.571
-----------------------+---------+----------
BOILER FIXTURES AND BELONGINGS.
A boiler is not complete without certain fixtures. There must be
a feed-pump or injector, with a supply-pipe, feed-valve, safety
feed-valve, and check-valve, in order to supply water properly to
the boiler; gauge-cocks, a glass water-gauge, a blow-pipe, with its
valve, to reduce the height of the water in the boiler, or to empty
it entirely; a safety-valve to allow the steam to escape from the
boiler when it exceeds a fixed pressure; a scumming apparatus to remove
the foreign matters from the water as much as possible; a steam-pipe
to convey the steam to the place where it is wanted; man-holes and
hand-holes, with their covers and guards, for examination and cleaning;
a non-corrosive steam-gauge, to accurately indicate at all times the
amount of pressure in the boiler; and a fusible plug to give warning in
case of “low water.”
Thus we see that in speaking of a boiler, not only the boiler proper is
meant, but also the whole of its fixtures and belongings, of which the
following is only a partial list:
Feed Pump,
Injector or Inspirator,
Check Valve,
Gauge Cocks,
Glass Water Gauge,
Try Cocks,
Blow-out Apparatus,
Blow-off Valve,
Safety Valve,
Scum Apparatus,
Steam Gauge,
Fusible Plug,
Surface Blow Cocks,
Grate Bars,
Baffle or Shield Plates,
Mud Drum,
Feed Water Heaters,
Boiler Fronts,
Dead Plate,
Steam Pressure Recording
Gauge,
Drain Cock for Steam Gauge,
Steam Trap,
Steam Whistle.
All these are attachments to the boiler proper, having direct reference
to its internal functions; but in addition there are the lugs,
pedestals, or brackets which support the boiler; the masonry in which
it is set, with its binders, rods, and wall-plates; the boiler front,
with its doors, anchor-bolts, etc.; the arch-plates, bearer-bars,
grate-bars, and dampers, and last, but not least, the chimney. These
are all equally necessary to enable the boiler to perform its duty
properly. And besides, there are required fire-tools, flue brushes and
scrapers, and scaling tools, with hose also, to wash out the boiler, to
say nothing of hammers, chisels, wrenches, etc.
The fittings and attachments of the marine boiler are similar to those
belonging to the land steam generators, and vary only in accommodating
themselves to their peculiar surroundings.
The proper operation of the boiler as to efficiency and economy is
largely dependent upon the number, appropriate proportion and harmony
of action of its numerous attachments, and the utmost care and skill
are requisite for designing and attaching them.
It must not be supposed that a complete list and description of all
steam boiler attachments are here presented—that were a task beyond the
limits of the entire volume.
BOILER FRONTS.
Boiler fronts are made in many different styles, almost every maker
having some peculiar points in design that he uses on his own boilers
and which nobody else uses.
In the illustrations here given may be seen the four principal designs:
1. The flush front is shown in Fig. 72.
2. The overhanging front as seen in Fig. 73.
3. The cutaway front, Fig. 74.
4. Fronts with breaching as shown in Fig. 75.
The flush front is one of the earliest forms of fronts, and though it
often gives good satisfaction, yet it is liable to certain accidents.
[Illustration: Front for Water Tube Boiler.—Fig. 71.]
[Illustration: Flush Front.—Fig. 72.]
As will be seen from cut 72, the front of the smoke arch, in this form
of setting, is flush with the front of the brickwork, and the dry sheet
just outside of the front head is built into the brickwork. The heat
from the fire, striking through the brickwork, impinges on this sheet,
which is unprotected by water on the inside. So long as the furnace
walls are in proper condition the heat thus transmitted should not be
sufficient to give trouble; but after running some time bricks are very
apt to fall away from over the fire door, and thus expose portions of
the dry sheet to the direct action of the fire, causing it to be burned
or otherwise injured by the heat, and perhaps starting a leakage around
the front row of rivets when the head is attached to the shell.
In the overhanging front this tendency is entirely prevented by setting
the boiler _in such a manner that the dry sheet projects out into the
boiler room_. If the brickwork over the fire door falls away when a
boiler is set in this manner, the only effect is to slightly increase
the heating surface. No damage can be done, since the sheet against
which the heat would strike is protected by water on the inside.
[Illustration: Overhanging Front.—Fig. 73.]
The objection is sometimes raised against the projecting front, that it
is in the way of the fireman. To meet this point and yet preserve all
the advantages of this kind of front, the cutaway style has come into
use. In this form the lower portion or the front sheet is cut obliquely
away, so that at the lowest point the boiler projects but little beyond
the brickwork.
[Illustration: Cutaway Front—Fig. 74.]
It will be noticed that in the flush and overhanging fronts, the doors
open sidewise, swing about on vertical hinges; in the cutaway front
the best way to arrange the tube door is to run a hinge along the top
of it, horizontally, and to have the door open upward. But with such a
disposition of things the door is not easy to handle. For the purpose
of support a hook and chain, hanging from the roof should be provided.
[Illustration: Front for Manhole.—Fig. 75.]
Fig. 75 shows a boiler the setting of which is similar in general
design to the other three, except that in the place of a cast-iron
front it has bolted to it a sheet iron breeching that comes down over
the tubes and receives the gases of combustion from them. In Fig. 75 a
manhole is shown under the tubes. This, of course, is not an essential
feature of the breeching, but it will be seen that manholes can readily
be put below the tubes on fronts of this kind, in such a manner as to
be very convenient of access.
In addition to these more general styles of boiler fronts, there are
fronts designed particularly for patent boilers, water-front boilers,
etc., which are made, very often, in ornamental and attractive designs.
In Fig. 71 is shown a beautiful and appropriate design in use in
connection with water tubular boilers.
FURNACE DOORS.
The chief points to be considered in the design of furnace doors are
to prevent the radiation of heat through them, and to provide for
the admission of air above the burning fuel in order to aid in the
consumption of smoke and unburnt gases.
In all cases where the doors are exposed to very rough usage—such,
for instance, as in locomotive and marine boilers—the means for
admitting air must be of the simplest, and consist generally of small
perforations as shown in Fig. 76 which represents a front view, and
section of the furnace door of a locomotive boiler. The heat from the
burning fuel is prevented from radiating through the perforation in
the outer door, by attaching to it a second or baffle plate, _a_, at a
distance of about 1-1/2 inches, the holes in which do not coincide in
direction with the door proper. By the constant entry of cold air from
the outside the greater part of any heat which may be communicated to
the door by radiation or conduction is returned to the furnace.
[Illustration: Fig. 76.]
Doors similar to the above provide for the constant addition of limited
quantities of fresh air above the fuel, but in actual practice,
however, air is only needed above the fire for a few minutes after
fresh fuel has been thrown on the grates and then is required in
considerable quantities. In the case of land boilers, the furnace
doors of which undergo comparatively mild treatment, it is possible to
introduce the necessary complications to effect this object.
[Illustration: Fig. 77.]
Fig. 77 shows an arrangement largely in use in New England, in which,
by means of a diaphragm, the air is passed back and forth across the
heated inner or baffle plate with the very best results.
The air is first drawn by the natural draught into the hollow space
between the iron door and its lining, through a row of holes _A_, in
the lower part of the door, controlled however, by a slide not shown
in the cut, then caused to flow back and forth across the width of
the door by simply arranged diaphragms, and finally injected into the
furnace through a series of minute apertures drilled in the upper part
of the door liner, as indicated in cut at _B_.
It will be seen that while the air may enter the door at a low
temperature, it constantly becomes heated during its circulation until
the instant it enters the furnace, it is ready to flash into flame with
intense heat upon its incorporation with the expanding gases of the
furnace.
An arrangement in common use in Cornish and Lancashire boilers consists
of a number of radial slits in the outer door which can be closed or
opened at will in the same manner as an ordinary window ventilator.
Other and more complicated arrangements have been frequently devised,
which work admirably so long as they remain in order, but the frequent
banging to which furnace doors are subjected, even in factory boilers,
soon deranges delicate mechanism.
Furnace doors should be made as small as possible considering the
proper distribution of fuel over the grate area, as otherwise the great
rush of cold air, when the door is opened rapidly, cools down the flues
and does considerable injury to tube plates, etc.; for this reason it
is desirable, when grates are over forty inches in width to have two
doors to each furnace, which can be fired alternately.
The great loss arising from a rush of cold air on opening the
furnace doors for replenishing the fires with fuel has led to costly
experiments to produce “a mechanical stoker,” or self boiler feeding
arrangement for supplying the coal as needed.
FUSIBLE PLUGS.
In some States the insertion of fusible plugs at the highest fire line
in boilers is compelled by law under a heavy penalty. Its design is
to give the most emphatic warning of low water, and at the same time
relieve the boiler of dangerous pressure.
[Illustration: Fig. 78.]
[Illustration: Fig. 79.]
Figs. 78 and 79 exhibit two of the forms most commonly used, and on
the succeeding page, in cut 80, is shown the device in operation where
the water has sunk to a dangerously low level. In the illustration
the device is shown in connection with a locomotive boiler, in the
common tubular boiler the plug is usually inserted in the rear head of
the boiler, so that in case of its operation it will not endanger the
fireman.
These devices are designed to be screwed into the boiler shell at the
safety line. The Figs. 78 & 79 exhibit their construction. The part
to be screwed into the boiler is called _the shell_ and is commonly
made of brass; the internal part is plug and is made of a soft metal
like banca tin or a compound consisting of lead, tin and bismuth. This
composition melts easily at the proper point to allow escape, where the
water has sunk to a dangerously low level.
There is considerable diversity in the make up of the material used for
filling the plug, which must not have its melting point at anything
less than the temperature of the steam lest it should “go off” at the
wrong time.
[Illustration: FUSIBLE SAFETY PLUG
Fig. 80.]
If the accident of low water occurs at a time where it is important to
continue operations with the least possible delay, a pine plug may be
driven in the opening left by the melting of the fusible metal. In any
event it is but a short job to renew the fusible cap, it being only
necessary to unscrew the nut and insert a new cap, the rest of the
device remaining intact.
The plug should be renewed occasionally and the surface exposed inside
the boiler be kept free from scale and deposit. It is to be understood
that the fusible portion extends entirely through the shell of the
boiler and when melted out makes a vent for the water or steam.
All marine boilers in service in the United States are required to have
fusible plugs, one-half inch in diameter, made of pure tin, and nearly
all first-class boiler makers put them in each boiler they build.
GRATE BARS.
[Illustration: Fig. 81.]
THE GRATE BARS are a very important part of the furnace appliances.
These consist of a number of cast iron bars supported on iron bearers
placed at and across the front and back of the furnace. Innumerable
forms of grate bars have been contrived to meet the cases of special
kinds of fuel. The type in common use is represented in Fig. 82.
[Illustration: Fig. 82.]
These cuts show a side view and a section of a single bar, and a plan
of three bars in position. Each bar is in fact a small girder, the top
surface of which is wider than the bottom. On each bar are cast lugs,
the width of which determines the size of the opening for the passage
of air. This opening varies in width according to the character of the
fuel; for anthracite 3/4 inch is a maximum, while the soft coals 5/8
to 3/4 inch is often used; for pea and nut coal still smaller openings
than either of those are used, _i.e._ 1/4 and 3/8 inches. For wood the
opening should be a full inch in width.
For long furnaces the bars are usually made into two lengths, with a
bearer in the middle of the grate, as shown in Fig. 83. As a rule long
grates are set with a considerable slope towards the bridge in order
to facilitate the distribution of the fuel; an inch to a foot is the
rule commonly approved.
[Illustration: Fig. 83.]
[Illustration: Fig. 84.]
_Rocking and shaking grates_ are now very extensively used; these
combine a dumping arrangement, and very largely lessen the great labor
of the fireman, and by allowing the use of slack and other cheap forms
of fuel are very economical. Several patents are issued upon this form
of grate bars all working on essentially the same principle. Fig. 84
exhibits an efficient form of a shaking grate. As shown in the cut,
the grates are arranged to dump the ashes and clinkers. By the reverse
motion the flat surface of the grates are restored.
Trouble with grate bars comes from warping or twisting caused by
excessive heat, and burning out, produced by the same cause—this
explains the peculiar shape in which grates are made—very narrow
and very deep. A free introduction of air not only causes perfect
combustion but tends towards the preservation of the bars.
Grate bars are usually placed so as to incline towards the rear, the
inclination being from one to two inches; this facilitates somewhat the
throwing of the coal into the furnace.
The proportion between grate and heating surface should be determined
by the kind of fuel to be used. The greatest economy will be attained
when the grate is of a size to cause the fire to be forced, and have
the gases enter the chimney only a few degrees hotter than the water in
the boiler.
If the grate is too large to admit of forcing the fire, the combustion
is naturally slower, and consequently the temperature in the furnace is
lower, and the loss from the escaping gases is greater.
It must be borne in mind that the only heat which can be utilized is
that due to the difference in temperature between the fire and the
water in the boiler. For example, if the temperature in the furnace be
975°, and the water in the boiler have a temperature due to 80 pounds
of steam, viz.: 325°, it is evident that the heat which can be utilized
is the difference between them, or 2/3 of the total heat. Now if the
fire be forced, and the furnace temperature raised to 2600°, 7/8 of the
total heat can be utilized; so it can be readily seen that the grate
should be of such a size as to have the fire burn rapidly.
The actual ratio of grate to heating surface should not in any case
be less than 1 to 40, and may with advantage, in many cases, be 1 to
50. This proportion will admit of very sharp fires, and still insure
the greater portion of the heat being transmitted to the water in the
boiler.
The water grate bars, invented in 1824, and since frequently applied to
locomotives and marine boilers, do not seem to grow in popular favor,
and are scarcely known in stationary boilers.
The objections urged against them are the expense of maintenance, their
fittings and attachments, and the possibility of serious consequences
should they rupture or burn out.
WATER GAUGE COCKS.
It is of the first importance that those in charge of a boiler shall
know with certainty the position of the water level within the boiler.
[Illustration: Fig. 85.]
These attachments, also called Try cocks, are usually placed in a
conspicuous and accessible position on the front of boilers. They are
so arranged that one will blow only steam, one at the working level of
the water, and the third at the lowest water level or say three inches
above the highest point of the fire line of the boiler. The cut, Fig.
85, exhibits them as commonly arranged.
It is not essentially requisite, that the cocks themselves should be
placed at the point indicated, so long as they have pipes projecting
internally into the boiler, with their ends corresponding to the height
of water above mentioned. In order that these cocks may readily be
cleaned out, a plug is usually fitted into bit of cock opposite the
port or opening of the plug, upon removing which a pricker can be
readily inserted.
The gauge or cocks should be tested many times each day, and when
opened the top one should always give _steam_ and the bottom one
_water_. They should be allowed to remain open long enough to make sure
whether steam or water is issuing from the cock. This is a matter of
instruction, but the beginner with a little experience can detect the
difference by the sound.
In so universal an appliance as this there are very many forms and
arrangements, but they all work upon the same principle as stated
above.
GLASS GAUGES.
These are the second and auxiliary arrangements for ascertaining
the water line. Nearly all boilers are supplied with both try cocks
and glass gauges, and so important is it considered to be correctly
informed as to the water line that a third method consisting of a float
which is carried on the water surface, is sometimes added to the two
named.
[Illustration: Fig. 86.]
The glass water gauge _column_ consists of an upright casting bolted to
the front of the boiler, in which are fixed two cocks having stuffing
boxes for receiving the gauge glass. The lower of these cocks is also
fitted with a drain cock for blowing out the glass.
The try cocks are frequently placed on the above-mentioned standard or
column.
The action of the gauge glass is to show the level of the water in the
boiler by natural gravitation and the best position for it is in view
of the engine room, as close to the boiler as possible and preferably
in the middle line of its diameter, at such height that its lowest
portion is about two inches above the highest part of the fire line of
the boiler, and its centre, nine inches above that, making the total
visible portion of glass eighteen inches long.
Glass water gauges sometimes have pipe connections top and bottom. The
object of this arrangement is to have an undisturbed water level in
the glass by carrying one pipe to the steam dome and the other near to
the bottom of the boiler; the one position not being so liable to be
affected by foaming and the other by the boiling of the water. Cocks
should always be fitted to the boiler ends of these pipes, in order
that in case of accident to the pipes, steam and water may be shut off.
The glasses are liable to burst and become choked up with dirt.
The former defect is easily repaired by shutting off the cocks in
connection with the boiler and putting in a new glass. The mud or
sediment is cleaned out by opening the above-mentioned drain or
blow-out cock and allowing the steam or water, or both, to rush through
the glass, which will effectually blow out all sediment and leave the
glass in good condition again to show the height of the water in the
boiler.
In opening the cocks connected with the glasses, it should be done
cautiously, as the glass is liable to burst.
A strip of white running the whole length of the glass on the side
toward the boiler is a great help in observing the variations of the
water line in the tube.
It is not needed to remove the gauge glasses to clean them. There are
good fixtures in the market that by taking out the plug in the top,
the glass may be cleaned with a bit of wicking on the end of a stick.
A slight scratch will break the glass, hence do not use wire. Use soft
rubber gaskets when setting the glass, screw up until all leaking
stops. Don’t let the glass come in contact with the metal _anywhere_.
Don’t try to reset the glass with an old hard gasket. Two glasses from
the same bundle will not act alike.
The glasses used to show the water line are made of a soft glass known
as “lead glass,” and are easily cut, or broken square across. Most
of them can be broken by filing a notch at the point at which it is
necessary to break them. After filing the notch, place the thumbs as
if you would break the glass; it will crack easily, and the fracture
be straight and clean. If the tube be brittle, as some are, to avoid
cutting the hands wrap two pieces of paper around the glass, each side
of the notch. If the ends are rough or uneven, they can be made smooth
by filing or by the grindstone.
The Manchester, Eng., Boiler Association attribute more accidents to
inattention to water gauges than to all other causes put together. It
is, therefore, of much importance that these glasses should be kept
clean. It is not an uncommon thing to go into a boiler room and find
that a leaky stuffing box has allowed the steam or water to blow out,
and, by running down the outside of the glass, leave a deposit of lime
scale. After this deposit has been formed, it is sometimes difficult
to remove—and more than a few glasses have been broken by the engineer
attempting to remove the scale. After this scale has once been formed,
unless it is soft enough to be wiped off with a piece of waste, it
is best to take the glass out and soak or wash it in a solution of
one-half muriatic acid and one-half water until it is clean or the
scale so softened that it may be readily wiped off. To prevent the
scale from again forming and hardening, the glass should be dipped in
glycerine before replacing.
THE MUD DRUM.
The mud drum is attached to a boiler with the expectation that it will
catch and hold the larger portion of the sediment precipitated from
the water. The mud drum to be effective should be protected from the
heat of the fire, for so soon as it receives sufficient heat to boil
the water within it can no longer serve the purpose for which it was
intended as all the sediment which may have gathered would be expelled
by the ebullition of the water. When the drum is located under the
boiler it is not in a good position to catch the sediment, as the
boiling water produces sufficient current to carry the sediment to the
top, or keep it violently agitated, so that there is little opportunity
for it to be deposited anywhere so long as the boiler is making steam.
Afterward when the water is quiet the sediment for the most part is
deposited on the tubes and the curve of the shell; the small portion
falling into the neck of the drum serves principally to show the
inefficiency of the device. Located under the boiler as it generally
is, makes it extremely difficult to get at for examination, and as
a consequence of its being enclosed, as it must be, to be of much
importance, it is subject to greater deterioration than would otherwise
be the case, and as the enclosure to be most efficient would enclose
the neck also, the difference of expansion at or near the junction
would soon produce leaking if not worse. When the mud drum is located
outside the boiler walls where it would be most efficient, if properly
connected, it loses its identity and becomes a mechanical boiler
cleaner. In consequence of these drawbacks the mud drum is becoming
antiquated as a boiler appliance, and is now seldom used.
BAFFLE PLATES.
These are a device sometimes used inside steam boilers to check the too
sudden flow of steam towards the exit pipe, they are simply plate to
baffle the rush of the steam so as to avoid foaming.
In Fig. 90 baffle plate is illustrated by the division casting against
which the steam strikes on its passage from the boiler to the engine.
The liners or inner plates of the boiler doors are baffle plates.
DEAD PLATE.
This is a flat plate of iron immediately inside the furnace door and is
used in many boilers in order to insure the more perfect combustion of
the coal.
When the fresh fuel is laid on, it is placed on the dead plate instead
of on the grate; in this position the coal is coked, the gases from
the coal being ignited as they pass over the already intensely hot
fuel in the furnace, the fuel from the dead plate is pushed forward to
make place for another charge to be put on the dead plate. But more
frequently, as elsewhere described, the fuel is thrown over and across
the dead plate directly upon the hot fire.
STEAM WHISTLES.
These are of two kinds, known as the bell-whistle and organ-tube
whistle; the latter is now fast superseding the former on account of
the simplicity of construction and superior tone. An improved form has
a division in the tube so as to emit two distinct notes, which may be
in harmony, or discord, and when sounded together may be heard a long
distance.
It is important that the whistle shall sound as soon as the steam
is turned on; to ensure this great care must be taken to keep the
whistle-pipe free from water.
THE STEAM GAUGE.
The principle of construction of the dial steam gauge is, that the
pressure may be indicated by means of a pointer in a divided dial
similar to a clock face, but marked in division, indicating pounds
pressure per square inch instead of hours and minutes.
Figs. 87 and 88 show the ordinary style of gauge which consists of an
elliptical tube, connected at one end to a steam pipe in communication
with the boiler pressure and at the other end with gearing to a pointer
spindle as shown in cut.
An inverted syphon pipe is usually formed under the gauge, its object
being to contain water and thus prevent the heat of the steam injuring
the machinery of the gauge, or distorting its action by expansion.
[Illustration: Fig. 87.]
[Illustration: Fig. 88.]
[Illustration: Fig. 89.]
A small drain cock should be fitted to the leg of the syphon of a steam
gauge, leading to the boiler, at a level with the highest point the
water can rise in the other leg, otherwise an increased pressure will
be indicated, due to the head of water which would otherwise collect in
the boiler leg of the syphon.
Steam gauges indicate the pressure of steam above the atmosphere only,
the total pressure being measured from a perfect vacuum which will add
14-7/10 lbs. on the average to the pressure shown on the steam gauge.
These gauges are apt to get out of order in consequence of water
lodging in the end of the heat tube and corroding the latter. It may
be easily known when they are out of order by raising the pressure of
the steam in the boiler and watching when it commences to blow off at
the safety valve, and then noting the position of the index finger. The
pressure registered by the finger should, of course, then correspond
with the known blow off pressure of the valves; if it does not, one or
the other or both of these instruments must be out of order; therefore,
when this is the case and a disagreement occurs, the steam gauge may be
presumed to need correction.
It should also be noted that the steam gauge finger points to zero when
steam pressure is cut off. A two-way cock should be used for closing
the connection between the steam gauge and the boiler, and at the same
time to let air into the steam gauge.
The steam should never be allowed to act directly on a steam gauge when
located in cold situations where they are liable to freeze. The valve
on the boiler should be closed and the water allowed to drip out, and,
before the steam is turned on from the boiler, the drip on the gauge
should be closed, in order that sufficient steam may be condensed in
the pipe to furnish the quantity of water necessary to keep the steam
from striking the gauge.
_A ready method for being always able to prove the correctness of your
steam gauge._
When steam is at some point not over half the usual pressure, place the
ball on the safety valve at the point where it commences to blow off
and mark the place. Move the ball twice as far from the fulcrum as this
mark, and it should blow off at twice the pressure as indicated by the
gauge, or it is not right. Any other relative distance may be used to
advantage.
STEAM SEPARATOR.
This appliance, which is also called an interceptor or catch water, is
generally a T shaped pipe.
[Illustration: Fig. 90.]
This, although not a boiler fixture or fitting, is intimately connected
with them: it is an appliance fast coming into use both for land and
marine engines, to guard against the danger to steam engine cylinders
arising from “the priming” of the boilers when the steam is used at a
high pressure with high speed of the piston.
The separator is usually placed in the engine room, so as to be well
in sight. The steam is led down the pipe round a diaphragm plate and
then up again to the engine steam pipe. By this means any priming or
particles of water that may be brought from the boiler with the steam
will fall to the bottom of the interceptor or catch water, from whence
it can be blown out, according to the arrangement of the pipes, by
opening the drain cock fixed on the bottom. It has a water gauge fixed
on the lower end, so as to show whether water is accumulating; and the
engineers attention is required to see that this water is from time to
time blown off.
In the illustration, Fig. 90, is shown the simplest form in which the
device can be made. The arrows exhibit the direction in which the steam
travels, the aperture whence the water is to be blown out and the
place for attachment of a water column. In practical construction the
separator should have a diameter twice that of the steam pipe and be
2-1/2 to 3 diameters long. It is often made with a round top and flat
bottom and sometimes with both ends hemispherical. The division plate
should extend half the diameter of the steam pipe below the level of
the bottom of the steam pipe.
In Fig. 91 is shown an improved form of a steam separator which
consists of a shell or casing in which there is firmly secured a
double-ended cone. On this cone there are cast a number of wings,
extending spirally along its exterior. On entering the separator the
steam is spread and thrown outward by the cone and given a centrifugal
motion by the spiral wings. These wings are constructed with a curved
surface.
It will be noticed that the steam on entering the separator is
immediately expanded from a solid body into an annular space of equal
volume to the steam pipe, whereby its particles are removed from the
centre and thus receive a greater amount of centrifugal motion. The
entrained water or grease, etc., is thus precipitated against, and
flows along the shell of the separator, and is collected in a well of
ample proportions at base of separator, where it is entirely isolated
from the flow of dry steam.
[Illustration: Fig. 91.]
SENTINEL VALVE.
It was formerly required for each marine boiler to have a small valve
loaded with a weight to a few pounds per square inch above the working
pressure, so that in case of the safety valves sticking fast and the
gauge being false, an alarm might be given when there was an excess of
pressure. Such valves were about 3/4 inch in diameter and sometimes
as small as 3/8. An arrangement of a small safety valve attached to
a whistle has been introduced, but with advances in other directions
relating to safety these specialties are now getting to be only known
by name.
DAMPER REGULATORS.
These are well-known devices for so controlling the draught of the
chimney that the steam pressure in the boiler will be increased or
decreased automatically, that is, without the aid of a person. The
regulator shown in Fig. 92, which is one of many excellent forms on the
market, has the power to move the damper in both directions by water
pressure, exerting a force on the end of the lever of nearly 200 lbs.,
thus compelling a certain and positive motion of the damper when a
variation in the boiler pressure takes place. It will open or close the
damper upon the variation of less than one pound of pressure. The close
regulation affords a test for the correctness of the steam gauge.
[Illustration: Fig. 92.]
This regulator, by using the water pressure from the boiler as a motive
power, becomes a complete engine without the connecting rod and crank,
having a balanced piston valve, the valve stem of which is enlarged
where it passes through the upper end of the chest into a piston of
small area, working in a small open ended cylinder cast on the chest.
The pressure forcing this piston outward is counterbalanced by weights
as shown in illustration.
The differential motion is accomplished by the device shown at the top
of small cylinder.
FUEL ECONOMIZER AND FEED WATER PURIFIER.
This device, shown in Fig. 93, is designed to utilize the waste
products of combustion as they pass from the furnace to the chimney.
Its use permits a high and consequently efficient temperature under the
boilers and yet saves the excess of heat. It acts also as a mechanical
boiler cleaner, furnishing a settling chamber for the deposit of the
impurities separated by the heat which nearly equals that of the live
steam in the boiler. This device adds largely to the water capacity of
the boiler, frequently containing one-half the weight of the water held
in the boiler itself.
It will be readily understood that the openings between the vertical
tubes are ample for the chimney flue area and that the device is
located between the chimney and the boiler, with the waste furnace heat
passing between the tubes.
[Illustration: Fig. 93.]
The economizer shown in Fig. 93 consists of sections of vertical
4-1/2″ boiler tubes fitted to their top and bottom headers by taper
joints. The top headers are provided with caps over each tube to permit
cleaning out the sediment and remove and replace any tube that may
become damaged. The several top headers are connected together at one
end by lateral openings and the bottom headers are also connected as
shown in cut, having hand holes opposite each bottom header to provide
for cleaning out.
_Mechanical scrapers_ are made to travel up and down each tube to keep
them clear of soot. These are controlled by an automatic mechanism and
driving head, as shown in Fig. 93.
The important features about the economizer are, 1, its adaptability
to any type of boiler, 2, the saving attained by utilizing that heat
which has necessarily been an almost total waste, 3, the purifying of
the water by means of the intense heat and slow circulation of the feed
water.
SAFETY VALVES.
[Illustration: Fig. 94.
(SECTIONAL VIEW.)]
_The safety valve_ is a circular valve seated on the top of the boiler,
and weighted to such an extent, that when the pressure of the steam
exceeds a certain point, the valve is lifted from its seating and
allows the steam to escape. Safety valves can be loaded directly with
weights, or the load can be transmitted to the valve by a lever. Again,
the end of the lever is sometimes held down by a spring, or the spring
may be applied directly to the valve seat.
Fig. 94 (2 views) exhibits _a spring loaded safety valve_. These are
generally provided with a reaction lip, surrounding the seat, which
causes them to open much further, and thus enables them to discharge a
larger volume of steam than a lever valve of equal diameter.
The operation can be easily understood by examining the figures. As
soon as the steam pressure is high enough to lift the valve disc clear
from its seat, the steam will escape around the valve seat as in an
ordinary lever safety valve, but instead of escaping directly into
the atmosphere, the current of steam is turned downward against the
reaction lip, by the curved projection on the valve disc, which can be
seen in the figure. The steam pressure is thus assisted in holding the
valve open, as well as raising it much higher, giving a larger opening
than would be the case if the valve were lifted by the pressure alone.
Spring loaded valves are mostly used on marine boilers, locomotives and
portable boilers, and wherever outside disturbances interfere with the
action of a weight.
_A “pop” safety valve_ is a common form of safety valve and takes its
name from the fact that it takes a little more pressure to raise it off
its seat than what it is set at, consequently it releases itself with a
“pop.”
[Illustration: Fig. 95.]
Fig. 95 shows a form of dead weight safety valves when _a_ is the valve
which rests on the seating _b_.
The valve is attached to the circular casting A, A, A, so that both
rise and fall together. The weights W, W, etc., are disposed on the
casting in rings, which can be adjusted to the desired blow off
pressure. Owing to the center of gravity of the casting and weight
being below the valve, the latter requires no requires no guides to
keep it in position. This is a great advantage as guides frequently
stick, and prevent the valve from acting. Another advantage of this
form of valve is, that it is difficult to tamper with. For instance, a
four-inch valve, intended to blow off at 100 lbs. per square inch would
require weight of over 1,200 lbs., which require a considerable bulk.
An unauthorized addition of a few pounds to such a mass would make no
appreciable addition to the blowing off pressure, while any effectual
amount added to the weight would be immediately noticed. It is quite
different with the lever safety valve about to be described, a small
addition to the weight at the end of the lever is multiplied several
times at the valve.
U. S. RULES RELATING TO SAFETY VALVES.
Extract from rules and regulations passed and approved Feb. 25, 1885,
by the United States Board of Supervising Inspectors of Steam Vessels:
SECTION 24. “Lever safety valves to be attached to marine boilers shall
have an area of not less than one square inch to two square feet of the
grate surface in the boiler, and the seats of all such safety valves
shall have an angle of inclination of forty-five degrees to the centre
line of their axis.
“The valves shall be so arranged that each boiler shall have one
separate safety valve, unless the arrangement is such as to preclude
the possibility of shutting off the communication of any boiler with
the safety valve or valves employed. This arrangement shall also apply
to lock-up safety valves when they are employed.
“Any spring-loaded safety valves constructed so as to give an increased
lift by the operation of steam, after being raised from their seats,
or any spring-loaded safety valve constructed in any other manner, or
so as to give an effective area equal to that of the aforementioned
spring-loaded safety valve, may be used in lieu of the common
lever-weighted valve on all boilers on steam vessels, and all such
spring-loaded safety valves shall be required to have an area of not
less than one square inch to three square feet of grate surface of the
boiler, and each spring-loaded valve shall be supplied with a lever
that will raise the valve from its seat a distance of not less than
that equal to one-eighth the diameter of the valve opening, and the
seats of all such safety valves shall have an angle of inclination
to the centre-line of their axis of forty-five degrees. But in no
case shall any spring-loaded safety valve be used in lieu of the
lever-weighted safety valve, without first having been approved by the
Board of Supervising Inspectors.”
The following size “Pop” Safety Valves are required for boilers having
grate surfaces as below:
2 inch “Pop” Valve for 9.42 square feet of grate surface.
2-1/2 inch “Pop” Valve for 14.72 square feet of grate surface.
3 inch “Pop” Valve for 21.20 square feet of grate surface.
4 inch “Pop” Valve for 37.69 square feet of grate surface.
5 inch “Pop” Valve for 58.90 square feet of grate surface.
6 inch “Pop” Valve for 84.82 square feet of grate surface.
PROFESSOR RANKIN’S RULE.—Multiply the number of pounds of water
evaporated per hour by .006, and the product will be the area in square
inches of the valve.
The U. S. Steamboat Inspection Law requires for the common lever valve
one square inch of area of valve for every two square feet of area of
grate surface.
United States Navy Department deduced from a series of experiments the
following rule: Multiply the number of pounds of water evaporated per
hour by .005, and the product will be the area of the valve in square
inches.
Rule adopted by the Philadelphia Department of Steam Engine and Boiler
Inspection:
1. Multiply the area of grate in square feet by the number 22.5. 2. Add
the number 8.62 to the pressure allowed per square inch. Divide (1) by
(2) and the quotient will be the area of the valve in square inches.
This is the same as the French rule.
The maximum desirable diameter for safety valves is four inches, for
beyond this the area and cost increase much more rapidly than the
effective discharging around the circumference.
There should not be any stop valve between the boiler and safety valve.
The common form of safety valve is shown in Fig. 96.
Here the load is attached to the end _B_ of the lever _A_, _B_, the
fulcrum of which is at _c_. The effective pressure on the valve, and
consequently the blowing off pressure in the boiler can be regulated
within certain limits, by sliding the weight _W_ along the arm of the
lever. In locomotive engines, as well as on marine boilers, the weight
would on account of the oscillations, be inadmissible and _a spring_ is
used to hold down the lever.
In the calculations regarding the lever safety valve, there are five
points to be determined, and it is necessary to know four of these in
order to find the fifth. These are: (1) The Steam Pressure, (2) The
Weight of Ball, (3) The Area of Valve, (4) The Length of Lever, (5) The
Distance from the Valve Centre to the Fulcrum.
[Illustration: Fig. 96.]
In making these calculations it is necessary to take into account the
load on the valve due to the weight of the valve-stem and lever. The
leverage with which this weight acts is measured by the distance of its
centre of gravity from the fulcrum. The centre of gravity is found by
balancing the lever on a knife edge, and the weight of the valve-stem
and lever can be found by actual weighing. This load can also be found
by attaching a spring balance to the lever exactly over the centre of
the valve stem when they are in position. The following examples will
be computed under these conditions: (1) Steam Pressure, 120 pounds; (2)
Weight of Ball, 100 pounds; (3) Weight of Valve and Lever, 60 pounds,
weighed in position; (4) Length of Lever, 45 inches; (5) Length of
Distance from Valve Centre to Fulcrum, 5 inches; (6) Area of Valve, 8
square inches.
_To find the area of the valve:_
RULE.—Multiply the length of the lever by the weight of the ball,
and divide the product by the distance from the valve centre to the
fulcrum, and to the quotient add the effective weight of the valve and
lever, and divide the sum by the steam pressure.
_Example._
45 inches, length of the lever,
100 pounds, weight of the ball,
----
Fulcrum, 5 in. )4500
----
900
60 pounds, weight of valve and lever,
----
Steam pressure 120 lbs. )960 (8 square inches, area of valve.
960
_To find the pressure at which the valve will blow off:_
RULE.—Multiply the length of the lever by the weight of the ball;
divide this product by the distance from the valve centre to the
fulcrum, and to the quotient add the effective weight of the lever and
valve, and divide the sum by the area of the valve.
_Example._
45 inches, length of lever,
100 pounds, weight of ball,
----
Fulcrum, 5 in. )4500
----
900
60 pounds, weight of valve and lever,
----
Area of Valve 8 ) 960
----
120 pounds, pressure at which valve will blow.
_To find the weight of ball:_
RULE.—Multiply the steam pressure by the area of the valve, and from
the product subtract the effective weight of the valve and lever, then
multiply the remainder by the distance from the valve centre to the
fulcrum, and divide the product by the length of the lever.
_Example._
120 pounds, steam pressure,
8 inches, area of valve,
----
960
60 pounds, weight of valve and lever,
----
900
5 inches, fulcrum,
----
Length of lever, 45 in. )4500
----
100 pounds, weight of ball.
_To find the length of lever:_
RULE.—Multiply the steam pressure by the area of the valve, and from
the product subtract the effective weight of the valve and lever, then
multiply the remainder by the distance from the valve centre to the
fulcrum, and divide the product by the weight of the ball.
_Example._
120 pounds, steam pressure,
8 inches, area of valve,
----
960
60 pounds, weight of valve and lever,
----
900
5
----
100)4500(45 length of lever.
Every boiler should be provided with two safety valves, one of which
should be put beyond the control of the attendant.
Safety valves that stick will do so even though tried every day, if
they are simply lifted and dropped to the old place on the seat again.
_If a boiler should be found with an excessively high pressure, it
would be one of the worst things to do to start the safety valve from
its seat unless extra weight was added_, for should the valve once
start, it would so suddenly relieve the boiler of such a volume of
steam as would cause a rush of water to the opening, and by a blow,
just the same as in water hammer, rupture the boiler.
Such a condition is very possible to occur of itself when a safety
valve sticks. The valve holds the pressure, that gets higher and
higher, until so high that the safety valve does give way and allows so
much steam to escape that the sudden changing of conditions sets the
water in motion, and an explosion may result.
The noise made by a safety valve when it is blowing off may be
regarded in two ways. First, by it is known that the valve is capable
of performing its proper function, and that there is, therefore, a
reasonable assurance that no explosion will result from excessive
pressure of steam or other gas, and on the other hand too much noise of
this kind indicates wasted fuel.
The hole of the safety valve may be 2, 3 or 4 inches; that does not
say that the area is 3.1416, 7.06 or 12.56 square inches, but the area
is that which is inside of the joint. The valve opening may be, say
2 inches, but _the circle of contact of valve to seat_ may be of an
average diameter of 2-1/8 inches, if so, all the close calculations
otherwise will not avail. In the first place, the area of 2 inches
equals 3.1416; that of 2-1/8 diameter equals 3.5466, showing a
difference of .4 square inches.
NOTE.
Very extended rules issued by the U. S. Government for calculating
the safe working pressure, dimensions and proportions of the safety
valves for marine boilers are reprinted in “Hawkins’ Calculations” for
engineers.
When a safety valve is described as a “2 inch safety valve,” etc.,
it means that two inches is _the diameter_ of the pipe; hence the
following rule and examples for finding the area.
RULE FOR FINDING AREA OF VALVE OPENING.
Square the diameter of the opening and multiply the product by the
decimal .7854.
EXAMPLE.
What is the area of a three inch valve? Now then:
3 × 3 = 9 × .7854 = 7.06 square inches, Ans.
NOTE.—A shorter method of calculating by .7854 in larger sums is to
multiply by 11 and divide by 14, for decimal .7855 = the fraction
11/14th. Note: .7854 is the area of a circular inch.
When valves rise from their seats under increasing steam pressure
they do so by a constantly diminished ratio which has been carefully
determined by experiment and reduced to the following table.
+----------------+----------------+
|Pressure in Lbs.| Rise of Valve. |
+----------------+----------------+
| 12 | 1-36 |
| 20 | 1-48 |
| 35 | 1-54 |
| 45 | 1-65 |
| 50 | 1-86 |
| 60 | 1-86 |
| 70 | 1-132 |
| 80 | 1-168 |
| 90 | 1-168 |
+----------------+----------------+
The following useful table was prepared by the Novelty Iron Works, New
York.
+----------------+----------------+
|Boiler Pressure |Area of Orifice |
| in Lbs. Above | in Sq. In. for |
|the Atmosphere. |Each Sq. Ft. of |
| |Heating Surface.|
+----------------+----------------+
| 0.25 | .022794 |
| 0.5 | .021164 |
| 1. | .018515 |
| 2. | .014814 |
| 3. | .012345 |
| 4. | .010582 |
| 5. | .009259 |
| 10. | .005698 |
| 20. | .003221 |
| 30. | .002244 |
| 40. | .001723 |
| 50. | .001389 |
| 60. | .001176 |
| 70. | .001015 |
| 80. | .000892 |
| 90. | .000796 |
| 100. | .000719 |
| 150. | .000481 |
| 200. | .000364 |
+----------------+----------------+
FEED WATER HEATERS.
[Illustration: Fig. 97.]
There are two forms of feed water heaters: (1) _The closed heater_,
where the feed water passes through tubes, which are enclosed in a
shell, through which the exhaust steam passes.(2) _The open heater_, in
which the steam and water come into contact. In the latter the water is
sprayed into a space, through which the exhaust steam passes, or is run
over a number of inclined perforated copper plates, mingled with the
exhaust steam.
The original feed water heater called a “pot heater,” consisted of
a vessel so constructed that the feed water was sprayed through the
exhaust steam into a globe formed tank, from the bottom of which the
heated water was pumped into the boiler; its name was originally the
“pot heater,” but as it was open to the air through the exhaust pipe,
it was, with its successively improved forms called the open heater.
All the heat imparted to the feed water, before it enters the boiler,
is so much saved, not only in the cost of fuel, but by the increased
capacity of the boiler, as the fuel in the furnace will not have this
duty to perform. There are two sources of waste heat which can be
utilized for this purpose: the chimney gases and the exhaust steam.
The gases escaping to the chimney after being reduced to the lowest
possible temperature contain a considerable quantity of heat. This
waste of heat energy may be largely saved by the device illustrated on
page 186.
[Illustration: Fig. 98.]
How much saving is obtained under any given condition is a question
requiring for its solution a careful calculation of all of the
conditions which have a bearing on the subject. Exhaust steam under
atmospheric pressure only has a sensible temperature of 212 degrees,
but exhaust steam contains also a large number of heat units which are
given up when the steam is condensed into water; for this reason it
might be thought possible to raise the temperature of the feed water a
few degrees higher even than the sensible temperature of the exhaust
steam. But this should not be expected, on account of the radiation of
heat that would occur above that of the steam.
The steam which escapes from the exhaust pipe dissipates into the
atmosphere or discharges into the condenser over nine tenths of the
heat it contained when leaving the boiler. This can be best utilized
by _exhaust feed water heaters_, for the use of live steam heaters
represents no saving in fuel, as all the heat imparted to the feed
water by their use comes directly from the boiler. The purpose for
which they are used is to elevate the temperature of the feed water
above the boiling point, so as to precipitate the sulphate of lime
and other scale forming substances, and prevent them from entering
the boiler. Neither does the heat in the feed water introduced by
an injector represent saving, as it comes from the boiler and was
generated by the fuel.
It is important to note these two statements: 1, That neither live
steam feed water heaters, nor 2, injectors save the heat from the
escaping steam.
It is also well to remember that it requires _a pound of water_ to
absorb 1.146 heat units, and that this quantity of heat is distributed
through the whole quantity of water, and _as a pound of steam is the
same as a pound of water_, it may be understood that at 212° each pound
of exhaust steam contains 1,146 heat units; ten pounds of steam contain
11,460 heat units distributed through the mass, etc.: thus, to explain
still further:
To evaporate water into steam, it must first be heated to the boiling
point, and then sufficient heat still further added to change it from
the liquid to the gaseous state, or steam. Take one pound of water at
32 degrees and heat it to the boiling point, it will have received 212°
- 32° = 180 heat units. A heat unit being the amount of heat necessary
to raise one pound of water through one degree at its greatest density.
To convert it into steam after it has been raised to the boiling point,
requires the addition of 966 heat units, which are called latent, as
they cannot be detected by the thermometer. This makes 180 + 966 =
1146 heat units, which is the total heat contained _in one pound of
water_ made into steam at the atmospheric pressure. And at atmospheric
density the volume of this steam is equal to 26.36 cubic feet, and this
amount of steam contains 1,146 units of heat, distributed throughout
the whole quantity, while the temperature at any given point at which
the thermometer may be inserted is 212 degrees. If two pounds of water
be evaporated, making a volume of 52.72 cubic feet, then the number of
heat units present would be doubled, while the temperature would still
remain at 212, the same as with one pound.
If by utilizing the heat that would otherwise go to waste, the
temperature of the feed water is raised 125 degrees, the saving would
be 125/1146 of the total amount of heat required for its evaporation,
or about 11 per cent. Thus it can be seen the percentage of saving
depends upon the initial temperature of the feed water, and the
pressure at which it is evaporated.
For example, a boiler carrying steam at 100 pounds pressure has the
temperature of the feed water raised from 60 to 200 degrees, what is
the percentage of gain?
By referring to a table pressure of “saturated steam,” it will be seen
that the total heat in steam at 100 pounds pressure is 1185 heat units.
These calculations are from 32 degrees above zero, consequently the
feed must be computed likewise.
In the first case, the heat to be supplied by the furnace is the total
heat, less that which the feed water contains, or 1185 - 28 = 1157
heat units. In the second case it is 1185 - 168 = 1017 heat units,
the difference being 1157 - 1017 = 140, which represents a saving of
140/1157 or about 12 per cent.
Where feed water is heated no more than 20 degrees above its normal
temperature the gain effected cannot amount to more than 2%, not
sufficient to pay for the introduction and maintenance of a feed water
heating device, no matter how simple, but if the temperature of the
water can be increased 60 degrees the gain will be in the neighborhood
of 5%. To make feed water heating practical and economical it would be
necessary to increase the temperature of the water about 180 degrees at
least, and to do this, using the exhaust from a non-condensing engine
without back pressure, would require such a capacity of heater as would
give fully 10 square feet of heating surface to each horse power of
work developed, and to raise the temperature above this would require a
certain amount of back pressure or an increased capacity of heater, so
that the subject resolves itself into a question of large capacity of
heater, or a higher temperature of the exhaust steam, which could only
be obtained through a given amount of back pressure.
In the same way has been calculated the following table, showing
percentages of saving of fuel by heating feed-water to various
temperatures by exhaust steam, otherwise waste:
_Percentage of saving._ (_Steam at 60 pounds gauge pressure._)
-----+--------------------------------------------------------------
Final| Initial Temperature of Water (Fahrenheit).
Temp.+--------+--------+--------+--------+--------+--------+--------
Fahr.| 32 Deg.| 40 Deg.| 50 Deg.| 60 Deg.| 70 Deg.| 80 Deg.| 90 Deg.
-----+--------+--------+--------+--------+--------+--------+--------
60 | 2.39 | 1.71 | 9.86 | … | … | … | …
80 | 4.09 | 3.43 | 2.59 | 1.74 | 0.88 | … | …
100 | 5.79 | 5.14 | 4.32 | 3.49 | 2.64 | 1.77 | .90
120 | 7.50 | 6.85 | 6.05 | 5.23 | 4.40 | 3.55 | 2.68
140 | 9.20 | 8.57 | 7.77 | 6.97 | 6.15 | 5.32 | 4.47
160 | 10.90 | 10.28 | 9.50 | 8.72 | 7.91 | 7.09 | 6.26
180 | 12.60 | 12.00 | 11.23 | 10.46 | 9.68 | 8.87 | 8.06
200 | 14.36 | 13.71 | 13.00 | 12.20 | 11.43 | 10.65 | 9.85
220 | 16.00 | 15.42 | 14.70 | 14.00 | 13.19 | 12.33 | 11.64
-----+--------+--------+--------+--------+--------+--------+--------
|100 Deg.|120 Deg.|140 Deg.|160 Deg.|180 Deg.|200 Deg.|
-----+--------+--------+--------+--------+--------+--------+--------
60 | … | … | … | … | … | … |
80 | … | … | … | … | … | … |
100 | … | … | … | … | … | … |
120 | 1.80 | … | … | … | … | … |
140 | 3.61 | 1.84 | … | … | … | … |
160 | 5.42 | 3.67 | 1.87 | … | … | … |
180 | 7.23 | 5.52 | 3.75 | 1.91 | … | … |
200 | 9.03 | 7.36 | 5.62 | 3.82 | 1.96 | … |
220 | 10.84 | 9.20 | 7.50 | 5.73 | 3.93 | 1.98 |
-----+--------+--------+--------+--------+--------+--------+--------
A good feed-water heater of adequate proportions should readily raise
the temperature of feed-water up to 200° Fahr., and, as is seen by
inspection of the table, thus effect a saving of fuel, ranging from
14.3 per cent. to 9.03 per cent., according as the atmospheric or
normal temperature of the water varies from 32° Fahr. in the height of
winter, to 100° Fahr. in the height of summer.
The percentage of saving which may be obtained from the use of exhaust
steam for heating the feed water, with which the boiler is supplied,
will depend upon the temperature to which the water is raised, and
this, in turn, will depend upon the length of time that the water
remains under the influence of the exhaust steam. This should be as
long as possible, and unless a sufficient amount of heating surface is
employed in the heater best results cannot be expected.
It does not necessarily require all the exhaust steam—or the whole
volume of waste steam passing from the engine to bring the feed water
up to the temperature desired, and the larger the heating appliance the
smaller proportion is needed—hence heaters are best made with two exits
nicely proportioned to avoid back pressure and at the same time utilize
enough of the exhaust to heat the feed water.
An impression prevails among many who are running a condenser on their
engine that a feed water heater can not be used in connection with it;
large numbers of heaters running on condensing engines with results as
follows: the feed water is delivered to the boiler at a temperature of
150° to 160° Fahr., depending on the vacuum: the higher the vacuum the
less the heat in the feed water.
A heater applied to a condensing engine generally increases the vacuum
one to two inches.
When cold water is used for the feed water, the saving in fuel by the
use of the heater is from 7 to 14 per cent.
When feed water is taken from the hot well, it will save 7 to 8 per
cent.
Where all the steam generated by a boiler is used in the engine and the
exhaust passed through a heater it is found by actual experiment, where
iron tubes are used in the heater, that approximately ten square feet
of heating surface will be required for each 30 lbs. of water supplied
to the boiler at a temperature of 200 degrees Fahr.
Ten square feet of heating surface in the feed water heater also
represents one horse power.
CAPACITY OF CISTERNS.
The following table gives the capacity of cisterns for each twelve
inches in depth:
_Diameter._ _Gallons._
25 feet 3671
20 „ 2349
15 „ 1321
14 „ 1150
13 „ 992
12 „ 846
11 „ 710
10 „ 587
9 „ 475
8 „ 376
7 „ 287
6-1/2 „ 247
6 „ 211
5 „ 147
4-1/2 „ 119
4 „ 94
3 „ 53
2-1/2 „ 36
2 „ 23
Supposing it was required to find the weight of the water in any
cistern or tank; it can be ascertained by multiplying the number of
gallons by the weight of one gallon, which is 8-1/3 pounds, 8.333. For
instance, taking the largest cistern in the above table containing 3671
gallons: 3671 × 8.33 = 30579.43 pounds.
The table above gives the capacities of round cisterns or tanks. If the
cistern is rectangular the number of gallons and weight of water are
found by multiplying the dimensions of the cistern to get the cubical
contents. For instance, for a cistern or tank 96 inches long, 72 inches
wide, and 48 inches deep, the formula would be: 96 × 72 × 48 = 331,776
cubic inches.
As a gallon contains 231 cubic inches; 331,776 divided by 231 gives
l,436 gallons, which multiplied by 8.33 will give the weight of water
in the cistern.
For round cisterns or tanks, the rule is: Area of bottom on inside
multiplied by the height, equals cubical capacity. For instance, taking
the last tank or cistern in the table: Area of 24 inches (diameter)
is 452.39, which multiplied by 12 inches (height) gives 5427.6 cubic
inches, and this divided by 231 cubic inches in a gallon gives 23
gallons.
Supposing the tank to be 24 inches deep instead of 12 inches, the
result would be, of course, twice the number of gallons.
RULE FOR OBTAINING CONTENTS OF A BARREL IN GALLONS.
Take diameter at bung, then square it, double it, then add square of
head diameter; multiply this sum by length of cask, and that product
by .2618 which will give volume in cubic inches; this, divided by 231,
will give result in gallons.
WATER METERS.
Water meters, or measurers (apparatus for the measurement of water),
are constructed upon two general principles: 1, an arrangement called
an “_inferential meter_” made to divert a certain proportion of the
water passing in the main pipe and by measuring accurately the small
stream diverted, _to infer_, or estimate the larger quantity; 2,
_the positive meter_; rotary piston meters are of the latter class
and the form usually found in connection with steam plants. They are
constructed on the positive displacement principle, and have only one
working part—a hard rubber rolling piston—rendering it almost, if not
entirely, exempt from liability to derangement. It measures equally
well on all sized openings, whether the pressure be small or great; and
its piston, being perfectly balanced, is almost frictionless in its
operation.
Constructed of composition (gun-metal) and hard rubber, it is not
liable to corrosion. An ingenious stuffing-box insures at all times a
perfectly dry and legible dial, or the registering mechanism which is
made of a combination of metals especially chosen for durability and
wear, and inclosed in a case of gun-metal.
[Illustration: Fig. 99.]
Fig. 99 is a perspective view of the meter, showing the index on the
top. It is shown here as when placed in position. The proper threads
at the inlet and outlet make it easy of attachment to the supply and
discharge pipes.
The hard rubber piston (the only working part of the Meter) is made
with spindle for moving the lever communicating with the intermediate
gear by which the dial is moved.
The water, through the continuous movement of the piston, passes
through the meter in an unbroken stream, in the same quantity as with
the pipe to which it is attached when the opening in the meter equals
that of the service pipe; the apparatus is noiseless and practically
without essential wear.
“POINTS” RELATING TO WATER METERS.
In setting a meter in position let it be plumb, and properly secured to
remain so. It should be well protected from frost.
If used in connection with a steam boiler, or under any other
conditions where it is exposed to a back pressure of steam or hot
water, it must be protected by a check valve, placed between the outlet
of the meter and the vessel it supplies.
It is absolutely necessary to blow out the supply pipe before setting a
new meter, so that if there be any accumulation of sand, gravel, etc.,
in it, the same may be expelled, and thus prevented from entering the
meter. Avoid using red lead in making joints. It is liable to work into
the meter and cause much annoyance by clogging the piston.
This engraving, Fig. 100, shows the counter of the Meter. It registers
cubic feet—one cubic foot being 7-48/100 U. S. gallons and is read in
the same way as the counters of gas meters.
[Illustration: Fig. 100.]
The following example and directions may be of service to those
unacquainted with the method:
If a pointer be between two figures, the smallest one must always be
taken. When the pointer is so near a figure that it seems to indicate
that figure exactly, look at the dial next below it in number, and if
the pointer there has passed 0, then the count should be read for that
figure. Let it be supposed that the pointers stand as in the above
engraving, they then read 28,187 cubic feet. The figures are omitted
from the dial marked “ONE,” because they represent but tenths of one
cubic foot, and hence are unimportant. From dial marked “10,” we get 7;
from the next marked “100,” we get 8; from the next marked “1,000,” we
get the figure 1; from the next marked “10,000,” the figure 8; from the
next marked “100,000,” the figure 2.
THE FISH TRAP used in connection with water meters is an apparatus (as
its name denotes) for holding back fishes, etc.
THE STEAM BOILER INJECTOR.
For safety sake, every boiler ought to have two feeds in order to avoid
accidents when one of them gets out of order, and one of these should
be an injector.
This consists in its most simple form, of a steam nozzle, the end of
which extends somewhat into the second nozzle, called the combining
or suction nozzle; this connects with or rather terminates in a third
nozzle or tube, termed the “forcer.” At the end of the _combining
tube_, and before entering the forcer, is an opening connecting the
interior of the nozzle at this point with the surrounding area. This
area is connected with the outside air by a check valve, opening
outward in the automatic injectors, and by a valve termed the overflow
valve.
The operation of the injector is based on the fact, first demonstrated
by Gifford, that the motion imparted by a jet of steam to a surrounding
column of water is sufficient to force it into the boiler from which
the steam was taken, and, indeed, into a boiler working at a higher
pressure. The steam escaping from under pressure has, in fact, a much
higher velocity than water would have under the same pressure and
condition. The rate of speed at which steam—taking it at an average
boiler pressure of sixty pounds—travels when discharged into the
atmosphere, is about 1,700 feet per second. When discharged with the
full velocity developed by the boiler pressure through a pipe, say
an inch in diameter, the steam encounters the water in the combining
chamber. It is immediately condensed and its bulk will be reduced say
1,000 times, but its velocity remains practically undiminished. Uniting
with the body of water in the combining tube, it imparts to it a large
share of its speed, and the body of water thus set in motion, operating
against a comparatively small area of boiler pressure, is able to
overcome it and pass into the boiler. The weight of the water to which
steam imparts its velocity gives it a momentum that is greater in the
small area in which its force is exerted than the boiler pressure,
although its force has actually been derived from the boiler pressure
itself.
The following cut 101 represents the outline of one of the best of a
large number of injectors upon the market, from which the operation of
injectors may be illustrated.
[Illustration:
S. Steam jet. V. Suction jet.
R. Ring or auxiliary check.
M. Steam valve and stem, handle.
X. Overflow cap.
C-D. Combining and delivery tube.
P. Overflow valve. O. Steam plug.
N. Packing nut. K. Steam valve
Fig. 101.]
The steam enters from above, the flow being regulated by the handle K.
The steam passes through the tube S and expands in the tube V, where it
meets the water coming from the suction pipe. The condensation takes
place in the tubes V and C, and a jet of water is delivered through
the forcer tube D to the boiler. Connection passages are made to the
chamber surrounding the tubes C, D, and to the end of tube V. If the
pressure in this surrounding chamber becomes greater than that of the
atmosphere, the check valve P is lifted and the contents are discharged
through the overflow.
So long as the pressure in this chamber is atmospheric, the check valve
P remains closed, and all the contents must be discharged through the
tube D.
There are three distinct types of live steam injectors, the “simple
fixed nozzle,” the “adjustable nozzle,” and the “double.” The first has
one steam and one water nozzle which are fixed in position but are so
proportioned as to yield a good result. There is a steam pressure for
every instrument of this type at which it will give a maximum delivery,
greater than the maximum delivery for any other steam pressure either
higher or lower. The second type has but one set of nozzles, but they
can be so adjusted relative to each other as to produce the best
results throughout a long range of action; that is to say, it so
adjusts itself that its maximum delivery continually increases with the
increase of steam pressure.
The double injector makes use of two sets of nozzles, the “lifter” and
“forcer.” The lifter draws the water from the reservoir and delivers it
to the forcer, which sends it into the boiler. All double injectors are
fixed nozzle.
All injectors are similar in their operation. They are designed to
bring a jet of live steam from the boiler in contact with a jet of
water so as to cause it to flow continuously in the direction followed
by the steam, the velocity of which it in part assumes, back into the
boiler and against its own pressure.
As a thermodynamical machine, the injector is nearly perfect, since
all the heat received by it is returned to the boiler, except such a
very small part as may be lost by radiation; consequently its thermal
efficiency should be in every case nearly 100 per cent. On the other
hand, because of the fact that its heat energy is principally used in
warming up the cold water as it enters the injector, its mechanical
efficiency, or work done in lifting water, compared with the heat
expended, is very low.
The action of the injector is as follows: Steam being turned on, it
rushes with great velocity through the steam nozzle into and through
the combining tube. This action induces a flow of air from the suction
pipe, which is connected to the combining tube, with the result that a
more or less perfect vacuum is formed, thus inducing a flow of water.
After the water commences to flow to the injector it receives motion
from the jet of steam; it absorbs heat from the steam and finally
condenses it, and thereafter moves on into the forcer tube simply as
a stream of water, at a low velocity compared with that of the steam.
At the beginning of the forcer tube it is subjected only to atmospheric
pressure, but from this point the pressure increases and the water
moves forward at diminished velocity.
“POINTS” RELATING TO THE INJECTOR.
In nine cases out of ten, where the injector fails to do good service,
it will be either because of its improper treatment or location, or
because too much is expected of it. The experience of thoroughly
competent engineers establishes the fact that in almost every instance
in which a reliable boiler feed is required, an injector can be found
to do the work, provided proper care is exercised in its selection.
The exhaust steam injector is a type different from any of the
above-named, in that it uses the exhaust steam from a non-condensing
engine. Exhaust steam has fourteen and seven-tenths (14.7) pounds of
work, and the steam entering the injector is condensed and the water
forced into the boiler upon the same general principle as in all
injectors.
The exhaust steam injector would be still more extensively used were it
not for a practical objection which has arisen—it carries over into the
boiler the waste oil of the steam cylinder.
Some injectors are called by special names by their makers, such as
ejectors and inspirators, but the term injectors is the general name
covering the principle upon which all the devices act.
The injector can be, and sometimes is, used as a pump to raise water
from one level to another. It has been used as an air compressor, and
also for receiving the exhaust from a steam engine, taking the place in
that case of both condenser and air pump.
The injector nozzles are tubes, with ends rounded to receive and
deliver the fluids with the least possible loss by friction and eddies.
Double injectors are those in which the delivery from one injector is
made the supply of a second, and they will handle water at a somewhat
higher temperature than single ones with fixed nozzles.
The motive force of the injector is found in the heat received from the
steam. The steam is condensed and surrenders its latent heat and some
of its sensible heat. The energy so given up by each pound of steam
amounts to about 900 thermal units, each of which is equivalent to a
mechanical force of 778 foot pounds. This would be sufficient to raise
a great many pounds of water against a very great pressure could it be
so applied, but a large portion of it is used simply to heat the water
raised by the injector.
The above explanation will apply to every injector in the market, but
ingenious modifications of the principles of construction have been
devised in order to meet a variety of requirements.
That the condensation of the steam is necessary to complete the process
will be evident, for if the steam were not condensed in the combining
chamber, it would remain a light body and, though moving at high speed,
would have a low degree of energy.
Certain injectors will not work well when the steam pressure is too
high. In order to work at all the injector must condense the steam
which flows into the combining tube. Therefore, when the steam pressure
is too high, and as a consequence the heat is very great, it is
difficult to secure complete condensation; so that for high pressure
of steam good results can only be obtained with cold water. It would
be well when the feed water is too warm to permit the injector to work
well, to reduce the pressure, and consequently the temperature of the
steam supplied to the injector, as low pressure steam condenses much
easier, and consequently can be employed with better result. Throttling
the steam supplied by means of stop valves will often answer well in
this case. The steam should not be cold or it will not contain heat
units enough to allow it to condense into a cross section small enough
to be driven into the boiler. This is the reason why exhaust injectors
fail to work when the exhaust steam is very cold. It also explains why
such injectors work well when a little live steam is admitted into the
exhaust sufficient to heat it above a temperature of 212°.
Leaks affect injectors the same as pumps, and in addition, the
accumulation of lime and other mineral deposits in the jets stops the
free flowing of the water. The heat of the steam is the usual cause of
the deposits, and where this is excessive it would be well to discard
the injector and feed with the pump.
The efficient working of the injector depends materially upon the size
of the jet which should be left as the manufacturer makes it; hence in
repairs and cleaning a scraper or file should not be used.
For cleaning injectors, where the jets have become scaled, use a
solution of one part muriatic acid to from nine to twelve parts of
water. Allow the tubes to remain in the acid until the scale is
dissolved or is so soft as to wash out readily.
The lifting attachment, as applied to any injector, is simply a steam
jet pump. It is combined with the injector proper and is operated by
a portion of the steam admitted to the instrument. Nearly all the
successful injectors on the market are made with these attachments, and
will raise water about 25 feet, if required, from a well or tank below
the boiler level.
Where an injector is required to work at different pressures it must
be so constructed that the space between the receiving tube and the
combining tube can be varied in size. As a rule this is accomplished by
making both combining and receiving tubes conical in form and arranging
the combining tube so that it can be moved to or from the receiving
tube, and the water space thereby enlarged or contracted at will. The
adjustment of the space between the two tubes by hand is a matter of
some difficulty, however; at least it takes more time and patience
than the average engineer has to devote to it, and the majority of the
injectors in use are therefore made automatic in their regulation.
The injector is not an economical device, but it is simple and
convenient, it occupies but a small amount of space, is not expensive
and is free from severe strains on its durability; moreover, where a
number of boilers are used in one establishment, it is very convenient
to have the feeding arrangements separate, so that each boiler is a
complete generating system in itself and independent of its neighbors.
LAWS OF HEAT.
Heat is a word freely used, yet difficult to define. The word “heat” is
commonly used in two senses: (1) to express the sensation of warmth;
(2) the state of things in bodies which causes that sensation. The
expression herein must be taken in the latter sense.
Heat is transmitted in three ways—by _conduction_, as when the end of
a short rod of iron is placed in a fire, and the opposite end becomes
warmed—this is conducted heat; by _convection_ (means of currents) such
as the warming of a mass of water in a boiler, furnace, or saucepan;
and by _radiation_, as that diffused from a piece of hot metal or
an open fire. Radiant heat is transmitted, like sound or light, in
straight lines in every direction, and its intensity diminishes
inversely as the square of the distance from its center or point of
radiation. Suppose the distance from the center of radiation to be 1,
2, 3 and 4 yards, the surface covered by heat rays will increase 1,
4, 9 and 16 square feet; the intensity of heat will diminish 1, 1/4,
1/9, and 1/16. and so on in like proportions, until the heat becomes
absorbed, or its source of supply stopped.
Whenever a difference in temperature exists, either in solids or
liquids that come in contact with or in close proximity to each other,
there is a tendency for the temperature to become equalized; if water
at 100° be poured into a vessel containing an equal quantity of water
at 50°, the tendency will be for the whole to assume a temperature of
75°; and suppose the temperature of the surrounding air be 30°, the
cooling process will continue until the water and the surrounding air
become nearly equal, the temperature of the air being increased in
proportion as that of the water is decreased.
The heat generated by a fire under the boiler is transmitted to the
water inside the boiler, when the difference in the specific gravities,
or, in other words, the cold water in the pipes being heavier than that
in the boiler sinks and forces the lighter hot water upward. This heat
is radiated from the pipes, which are good conductors of heat to the
air in the room, and raises it to the required temperature. That which
absorbs heat rapidly, and parts with it rapidly, is called a good
conductor, and that which is slow to receive heat, and parts with it
slowly, is termed a bad conductor.
The following tables of conductivity, and of the radiating properties
of various materials, may be of service:
CONDUCTING POWER OF VARIOUS SUBSTANCES.—DESPRITZ.
_Material._ _Conductivity._
Gold 100
Silver 97
Copper 89
Brass 75
Cast iron 56
Wrought iron 37
Zinc 36
Tin 30
Lead 18
Marble 2.4
Fire clay 1.1
Water 0.9
RADIATING POWER OF VARIOUS SUBSTANCES.—LESLIE
_Radiating_
_Material._ _Power._
Lampblack 100
Water 100
Writing paper 98
Glass 90
Tissue paper 88
Ice 85
Wrought lead 45
Mercury 20
Polished lead 19
Polished iron 15
Gold, silver 12
Copper, tin 12
From the above tables, it will be seen that water, being an excellent
radiator, and of great specific heat, and iron a good conductor, these
qualities, together with the small cost of the materials, combine to
render them efficient, economic and convenient for the transmission and
distribution of artificial heat.
By adopting certain standards we are enabled to define, compare and
calculate so as to arrive at definite results, hence the adoption of a
standard unit of heat, unit of power, unit of work, etc.
The standard unit of heat is the amount necessary to raise the
temperature of one pound of water at 32° Fahr. one degree, _i.e._, from
32° to 33°.
Specific heat is the amount of heat necessary to raise the temperature
of a solid or liquid body a certain number of degrees; water is adopted
as the unit or standard of comparison. The heat necessary to raise one
pound of water one degree, will raise one pound of mercury about 30
degrees, and one pound of lead about 32 degrees.
TABLE OF THE SPECIFIC HEAT OF EQUAL WEIGHTS OF VARIOUS SUBSTANCES.
_Specific_
_Solid bodies._ _Heat._
Wood (fir and pine) 0.650
„ (oak) 0.570
Ice 0.504
Coal 0.280
Charcoal (animal) 0.260
„ (vegetable) 0.241
Iron (cast) 0.241
Coke 0.201
Limestone 0.200
Glass 0.195
Steel (hard) 0.117
„ (soft) 0.116
Iron (wrought) 0.111
Zinc 0.095
Copper (annealed) 0.094
„ (cold hammered) 0.093
Tin 0.056
Lead 0.031
_Liquids._
Water 1.000
Alcohol 0.158
Acid (pyroligneous) 0.590
Ether 0.520
Acid (acetic) 0.509
Oil (olive) 0.309
Mercury 0.033
_Gases._
Hydrogen 3.409
Vapor of alcohol 0.547
Steam 0.480
Carbonic oxide 0.245
Nitrogen 0.243
Oxygen 0.217
Atmospheric air 0.237
Carbonic acid 0.202
THE STEAM PUMP.
It is difficult to overestimate the importance, in connection with a
steam plant, of the appliance which supplies water for the boiler, not
only, but a hundred other uses. Upon the steady operation of the pump
depends the safety and comfort of the engineer, owner and employee, and
indirectly of the success of the business with which the “plant” is
connected. Hence the necessity of acquiring complete knowledge of the
operation of a device so important.
[Illustration: Fig. 102.]
Pumps now raise, convey and deliver water, beer, molasses, acids,
oils, melted lead. Pumps also handle, among the gases, air, ammonia,
lighting gas, and oxygen. Pumps are also used to increase or decrease
the pressure of a fluid.
Pumps are made in many ways, and defined as rope, chain, diaphragm,
jet, centrifugal, rotary, oscillating, cylinder.
Cylinder pumps are of two classes, single acting and double acting.
In single acting—in effect is _single ended_—in double acting, the
motion of the cylinder in one direction causes an inflow of water and
a discharge at the same time, in the other; and on the return stroke
the action is renewed as the discharge end becomes the suction end. The
pump is thus double acting.
A _direct pressure_ steam pump is one in which the liquid is pressed
out by the action of steam upon its surface, without the intervention
of a piston. A direct acting steam pump is an engine and pump combined.
A cylinder or reciprocating pump is one in which the piston or plunger,
in one direction, causes a partial vacuum, to fill which the water
rushes in pressed by the air on its head.
NOTE.—A _suction valve_ prevents the return of this water on the return
stroke of the piston, and a _discharge valve_ permits the outward
passage of the fluid from the pump but not its return thereto or to the
reservoir through the suction pipe.
The force against which the pump works is gravity or the attraction of
the earth which prevents the water from being lifted. This is shown
by the fact that water can be led, or trailed, an immense distance,
limited only by the friction, by a pump.
NOTE.—It may be noted that the difference between a fluid and _liquid_
is shown in the fact that the latter can be poured from one vessel to
another, thus: air and water are both fluids, but of the two water
alone is liquid: air, ammonia, etc., are _gases_, while they are also
fluids, _i.e._, they flow.
The idea entertained by many that water is raised by suction, is
erroneous. Water or other liquids are raised through a tube or hose by
the pressure of the atmosphere on their surface. When the atmosphere is
removed from the tube there will be no resistance to prevent the water
from rising, as the water outside the pipe, still having the pressure
of the atmosphere upon its surface, forces water up into the pipe,
supplying the place of the excluded air, while the water inside the
pipe will rise above the level of that outside of it proportionally to
the extent to which it is relieved of the pressure of the air.
If the first stroke of a pump reduces the pressure of the air in the
pipe from 15 pounds on the square inch to 14 pounds, the water will be
forced up the pipe to the distance of 2-1/4 feet, since a column of
water an inch square and 2-1/4 feet high is equal in weight to about
1 pound. Now if the second stroke of the pump reduces the pressure of
the atmosphere in the pipe to 13 pounds per inch, the water will rise
another 2-1/4 feet; this rule is uniform, and shows that the rise of
the column of water within the pipe is equal in weight to the pressure
of the air upon the surface of the water without.
There are pumps (Centrifugal) especially designed for pumping water
mingled with mud, sand, gravel, shells, stones, coal, etc., but with
these the engineer has but little to do, as they are used mostly for
wrecking and drainage.
The variety of pattern in which pumps are manufactured and the still
greater variation in capacity forbids an attempt to fully illustrate
and describe further than their general principles, and to name the
following general
CLASSIFICATION OF PUMPS.
1st. Pumps are divided into Vertical and Horizontal.
Vertical pumps are again divided into:
1. Ordinary Suction or Bucket Pumps.
2. Suction and Lift Pumps.
3. Plunger or Force Pumps.
4. Bucket and Plunger Pumps.
5. Piston and Plunger Pumps.
Horizontal Pumps are divided into:
1. Double-acting Piston Pumps.
2. Single-acting Plunger Pumps.
3. Double-acting Plunger Pumps.
4. Bucket and Plunger Pumps.
5. Piston and Plunger Pumps.
[Illustration: Fig. 103.
A—Air Chamber.
B—Water Cylinder Cap.
C—Water Cylinder with Valves and Seats in.
D—Rocker Shafts, each, Long or Short.
E—Removable Cylinders, each.
F—Water Piston and Follower, each.
„—Water Piston Followers, each.
G—Rocker Stand.
H—Suction Flange, threaded.
I—Discharge Flange, threaded.
J—Intermediate Flanges, each.
K—Water Cylinder Heads, each.
L—Concaves complete, with Stuffing Boxes, each.
M—Steam Cylinder, without Head, Bonnet and Valve.
N—Steam Cylinder Foot.
O—Crosshead Links, each.
P—Steam Piston complete with Rings and Follower, each.
m—Steam Piston Head.
n—Steam Piston Follower.
Steam Piston Rings, including Spring and Breakjoint.
Q—Side Water Cylinder Bonnet, each.
R—Steam Chest Bonnet, each.
S—Steam Chest Stuffing Box Gland, each.
T—Steam Slide Valve, each.
U—Piston Rods, each.
V—Crossheads, each.
W—Rocker Arms, each, Long or Short.
X—Valve Rod Links, each, Long or Short.
Y—Steam Valve Stems, each.
Z—Steam Cylinder Heads, each.
aa—Piston Rod Nuts, each.
hh—Piston Rod Stuffing Glands, each.
ii—Water Valve Seats, each.
jj—Rubber Valves, each.
kk—Water Valve Stems, each.
ll—Water Valve Springs, each.
gg—Removable Cylinder Screws, each.
b—Steam Valve Stem Forks, each.
c—Steam Valve Stem Fork Bolts, each.
e—Valve Rod Link Bolts, each.
d—Rocker Arm Pins, each.
f—Crosshead Link Bolts, each.
o—Collar Bolts, each.
pp—Brass Steam Cylinder Drain Cocks, each.
Water Packings, each.
Brass Piston Rods, each.
Brass Lined Removable Cylinders, extra, each.
Piston Rod Stuffing Gland Bolts, each.
Water Cylinder Cap Bonnets, each.
Top Valve Caps, each.
Valve Cap Clamps, each.
]
In Figs. 102 and 103 are exhibited the outlines of _the double acting
steam pump_, which is undoubtedly the pattern most thoroughly adapted
for feeding steam boilers, as it is equipped for the slowest motion
with less risk of stopping on a centre.
From the drawing with reference letters may be learned the terms
applied generally to the parts of all steam pumps: example: “k” shows
the water valve stems, “K” the water cylinder heads.
It may be remarked that nearly all pump makers furnish valuable printed
matter, giving directions _as to repairs_, and best method of using
their particular pumps—especially valuable are their repair sheets in
which are given cuts of “parts” of the pumps. It were well for the
steam user and engineer to request such matter from the manufacturers
for the special pump they use.
POINTS RELATING TO PUMPS.
Blow out the steam pipe thoroughly with steam before connecting it to
the engine; otherwise any dirt or rubbish there might be in the pipe
will be carried into the steam cylinder, and cut the valves and piston.
Never change the valve movement of the engine end of the pump. If any
of the working parts become loose, bent or broken, replace them or
insert new ones, in precisely the same position as before.
Keep the stuffing boxes nearly full of good packing well oiled, and set
just tight enough to prevent leakage without excessive friction.
Use good oil only, and oil the steam end just before stopping the pump.
It is absolutely necessary to have a full supply of water to the pump.
If possible avoid the use of valves and elbows in the suction pipe, and
see that it is as straight as possible; for bends, valves and elbows
materially increase the friction of the water flowing into the pump.
See that the suction pipe is not imbedded in sand or mud, but is free
and unobstructed.
All the pipes leading from the source of supply to the pump must be
air-tight, for a very small air-leak will destroy the vacuum, the pump
will not fill properly; its motion will be jerky and unsteady, and the
engine will be liable to breakage.
A suction air chamber (made of a short nipple, a tee, a piece of pipe
of a diameter not less than the suction pipe and from two to three feet
long, and a cap, screwed upright into the suction pipe close to the
pump) is always useful; and where the suction pipe is long, in high
lifts, or when the pump is running at high speed, it is a positive
necessity.
Never take a pump apart before using it. If at any time subsequently
the pump should act badly, always examine the pump end first. And if
there is any obstruction in the valve, remove it. See that the pump is
well packed, and that there are no cracks in pipes or pump, nor any
air-leaks.
In selecting a pump for boiler feeding it is well to have it plenty
large enough, and also these other desirable features: few parts, have
no dead points or center, be quiet in operation, economical of steam
and repairs, and positive under any pressure.
Granted motion to the piston or plunger, a pump fails because it
leaks. There can be no other reason, and the leak should be found and
repaired. Leaky valves are common and should be ground. Leaky pistons
are not so common, but sometimes occur. Repairing is the remedy. Leaky
plungers are common. They need re-turning. The rod must be straight as
far as in contact with the packing. The packing around the plungers is
sometimes neglected too long, gets filled with dirt and sediment, and
hardens and scores an otherwise perfect rod, and so leaks.
The lifting capacity of a pump depends upon proper proportion of
clearance in the cylinder and valve chamber, to displacement of the
piston and plunger.
An injector is a sample of a _jet pump_—this may either lift or force
or both.
The most necessary condition to the satisfactory working of the steam
pump is a full and steady supply of water. The pipe connections should
in no case be smaller than the openings in the pump. The suction lift
and delivery pipes should be as straight and smooth on the inside as
possible.
When the lift is high, or the suction long, a foot valve should be
placed on the end of the suction pipe, and the area of the foot valve
should exceed the area of the pipe.
The area of the steam and exhaust pipes should in all cases be fully as
large as the nipples in the pump to which they are attached.
The distance that a pump will lift or draw water, as it is termed,
is about 33 feet, because water of one inch area 33 feet weighs 14.7
pounds; but pumps must be in good order to lift 33 feet, and all pipes
must be air-tight. Pumps will give better satisfaction lifting from 22
to 25 feet.
In cold weather open all the cocks and drain plugs to prevent freezing
when the pump is not in use.
When purchasing a steam pump to supply a steam boiler, one should be
selected capable of delivering one cubic foot of water per horse-power
per hour.
No pump, however good, will lift hot water, because as soon as the air
is expelled from the barrel of the pump the vapor occupies the space,
destroys the vacuum, and interferes with the supply of water. As a
result of all this the pump knocks. When it becomes necessary to pump
hot water, the pump should be placed below the supply, so that the
water may flow into the valve chamber.
The air vessel on the delivery pipe of the steam pump should never be
less than five times the area of the water cylinder.
There are many things to be considered in locating steam pumps, such as
the source from which water is obtained, the point of delivery, and the
quantity required in a given time; whether the water is to be lifted or
flows to the pump; whether it is to be forced directly into the boiler,
or raised into a tank 25, 50 or 100 feet above the pump.
The suction chamber is used to prevent pounding when the pump reverses
and to enable the pump barrel to fill when the speed is high.
Suction is the unbalanced pressure of the air which is at sea level
14-7/10 per inch, or 2096.8 per square foot.
When a valve is spoken of in connection with a pump it may be
understood that there may be several valves dividing and performing the
functions of one.
A simple method of obtaining tight pump-valves consists simply in
grooving the valve-sheets and inserting a rubber cord in the grooves.
As the valves seat themselves the cord is compressed and forms a tight
joint. An additional advantage is that it prevents the shock ordinarily
produced by rapid closing and prolongs the life of the valve seat. The
rubber cord when worn can be easily and quickly replaced.
CALCULATIONS RELATING TO PUMPS.
_To find the pressure in pounds per square inch_ of a column of water,
multiply the height of the column in feet by .434, Approximately, we
say that every foot elevation is equal to 1/2 lb. pressure per square
inch; this allows for ordinary friction.
_To find the diameter of a pump cylinder_ to move a given quantity of
water per minute (100 feet of piston being the standard of speed),
divide the number of gallons by 4, then extract the square root, and
the product will be the diameter in inches of the pump cylinder.
_To find quantity of water_ elevated in one minute running at 100 feet
of piston speed per minute. Square the diameter of the water cylinder
in inches and multiply by 4. Example: capacity of a 5 inch cylinder is
desired. The square of the diameter (5 inches) is 25, which, multiplied
by 4, gives 100, the number of gallons per minute (approximately).
_To find the horse power_ necessary to elevate water to a given height,
multiply the weight of the water elevated per minute in lbs. by the
height in feet, and divide the product by 33,000 (an allowance should
be added for water friction, and a further allowance for loss in steam
cylinder, say from 20 to 30 per cent.).
_The area of the steam piston_, multiplied by the steam pressure, gives
the total amount of pressure that can be exerted. _The area of the
water piston_, multiplied by the pressure of water per square inch,
gives the resistance. _A margin_ must be made between the _power_ and
the _resistance_ to _move_ the piston at the required speed—say from 20
to 40 per cent., according to speed and other conditions.
_To find the capacity of a cylinder_ in gallons. Multiplying the area
in inches by the length of stroke in inches will give the total number
of cubic inches; divide this amount by 231 (which is the cubical
contents of a U. S. gallon in inches), and product is the capacity in
gallons.
The temperature 62° F. is the temperature of water used in calculating
the specific gravity of bodies, with respect to the gravity or density
of water as a basis, or as unity.
[Illustration: Fig. 104.]
Important stress has been laid upon keeping all floating objects,
gravel, etc., away from the acting parts of the pump. In Fig. 104 is
presented a cut of an approved strainer which can be removed, freed
from obstruction, and replaced by simply slacking one bolt, the entire
operation occupying one minute. The advantages of this strainer will be
readily apparent.
IMPORTANT PRINCIPLES RELATING TO WATER.
There are some underlying natural laws and other data relating to water
which every engineer should thoroughly understand. Heat, _water_,
steam, are the three properties with which he has first to deal.
_Weight of one cubic foot of Pure Water._
At 32° F. = 62.418 pounds.
At 39.1°F = 62.425 „
At 62° (Standard temperature) = 62.355 „
At 212° = 59.640 „
The weight of a cubic foot of water is about 1000 ounces (exactly 998.8
ounces), at the temperature of maximum density.
The weight of a cylindrical foot of water at 62° F. is 49 lbs.
(nearly). The weight of a cylindrical inch is 0.4533 oz.
There are four notable temperatures for water, namely,
32° F., or 0° C. = the freezing point under one atmosphere.
39.1° or 4° = the point of maximum density.
62° or 16°.66 = the standard temperature.
212° or 100° = the boiling point, under one atmosphere.
_Water rises to the same level in the opposite arms of a recurved
tube_, hence water will rise in pipes as high as its source.
_The pressure on any particle of water is proportioned to its depth
below the surface_, and as the side pressure is equal to the downward
pressure.
_Water at rest presses equally in all directions._ This is a most
remarkable property, the upward direction of the pressure of water is
equal to that pressing downwards, and the side pressure is also equal.
_Any quantity of water, however small, may be made to balance any
quantity, however great._ This is called the Hydrostatic Paradox, and
is sometimes exemplified by pouring liquids into casks through long
tubes inserted in the bung holes. As soon as the cask is full and
the water rises in the pipe to a certain height the cask bursts with
violence.
_Water is practically non-elastic._ A pressure has been applied of
30,000 pounds to the square inch and the contraction has been found to
be less than one-twelfth.
_The surface of water at rest is horizontal._ A familiar example of
this may be noted in the fact that the water in a battery of boilers
seeks a uniform level, no matter how much the cylinders may vary in
size.
_A given pressure or blow impressed on any portion of a mass of water
confined in a vessel is distributed equally through all parts of the
mass_; for example a plug forced inwards on a square inch of the
surface of water, is suddenly communicated to every square inch of the
vessel’s surface, however large, and to every inch of the surface of
any body immersed in it.
WEIGHT AND CAPACITY OF DIFFERENT STANDARD GALLONS OF WATER.
+-------------+------------+------------+------------+------------+
| |Cubic inches|Weight of a |Gallons in a|Weight of a |
| |in a Gallon.| Gallon in | cubic foot.| cubic foot |
| | | pounds. | | of water, |
+-------------+------------+------------+------------+ English |
|Imperial or | | | | standard, |
| English | 277.264 | 10.00 | 6.232102 |62.221 lbs. |
|United States| 231. | 8.33111 | 7.480519 |Avoirdupois.|
+-------------+------------+------------+------------+------------+
STORING AND HANDLING OF COAL.
The best method of storing coal is a matter of economy and needs the
attention of the engineer.
Coal, as it comes from the mine, is in the best possible condition for
burning in a furnace; its fracture is bright and clean, and it ought
to be preserved up to the time of using it in such manner as to avoid
as much as possible any alteration of its condition so as to prevent
deterioration.
So far as actual experience goes it has been found that a brick
building, with double walls to promote coolness, with high narrow slits
instead of windows, with ventilating holes along the bottom of the
walls, having a high-pitched roof with overhanging eaves, and holes for
ventilation well sheltered under the eaves, and with ventilators along
the edge of the roof, is best suited to keep the coal in the condition
most nearly approaching that of the freshly mined. The floor of the
building should be preferably paved with brick on edge or flagstones;
the doors should be large and kept open in damp weather, and closed
when the weather is hot.
Some persons recommend sprinkling the coal occasionally during the hot
weather, but it is much better to wet down the paving all around the
building outside, and the exposed floor of the building, as well as the
walls inside and outside, and let the moisture of the evaporation have
its effect upon the coal. It will be found to be amply sufficient for
the purpose.
It has been found long since that it is better to have coal sheds dark,
as light assists greatly in impairing the fuel.
The best arrangement for a boiler room floor is to have a coal-bin,
paved with stone flags, opening into the fire-room by a door, while the
fire-room itself should be paved diagonally with brick, set on edge
upon a concrete foundation, well rammed to within about three feet of
the boiler front, and the remaining space should be floored with iron
plates.
The coal should be wheeled from the bins and dumped upon these plates,
never on the brick floor. These plates should be laid on an incline
of about an inch toward the boilers, and it is well to have a trough
or gutter, of about six inches in width, and having a depth of about
one and a half inches cast in them, at the edge lying nearest the
boilers, so that the water from the gauge-cock, drip-pipes, and that
from wetting down the ashes may run into it and drain into a proper
sewer-pipe laid under the flooring.
CHEMISTRY OF THE FURNACE.
A careful estimate by a Broadway Chemist of the contents or
constituents of a ton of coal presents some interesting facts, not
familiar certainly to unscientific minds. It is found that, besides
gas, a ton of ordinary gas coal will yield 3,500 pounds of coke, twenty
gallons of ammonia water and 140 pounds of coal tar. Now, destructive
distillation of this amount of coal tar gives about seventy pounds of
pitch, seventeen pounds of creosote, fourteen pounds of heavy oils,
about nine and a half pounds of naphtha yellow, six and one-third
pounds of naphthaline, four and three-fourth pounds of alizarine,
two and a fourth pounds of solvent naphtha, one and a fifth pound of
aniline, seventy-nine hundredths of a pound of toludine, forty-six
hundredths of a pound of anthracine, and nine-tenths of a pound of
toluches—from the last-named substance being obtained the new product,
saccharine, said to be 230 times as sweet as the best cane sugar.
From an engineer’s standpoint the main constituents of all coal are
carbon and hydrogen; in the natural state of coal these two are
united and solid; their respective characters and modes of entering
into combustion, are however essentially different. The hydrogen is
convertable into heat only in the gaseous state; the carbon, on the
contrary, is combustible only in the solid condition. It must be borne
in mind that neither is combustible while they are united.
There are, however, other elements existing in coal in its natural
state, and new ones are formed during burning or combustion as will be
noted in the succeeding paragraphs.
For raising steam the process of combustion consists in disentangling,
letting loose or evolving the different elements locked up in coal; the
power employed in accomplishing this is _heat_. The chemical results of
this consumption of the fuels may be divided into four stages or parts.
First stage, application of existing heat to disengage the constituent
gases of the fuel. In coals this is principally mixed carbon and
hydrogen.
Second stage, application or employment of existing heat to separate
the carbon from the hydrogen.
Third stage, further employment of existing heat to increase the
temperature of the two combustibles, carbon and hydrogen, until they
reach the heat necessary for combination with the air. If this heat is
not obtained, chemical union does not take place and the combustion is
imperfect.
Fourth and last stage, the union of the oxygen of the air with the
carbon and hydrogen of the furnace in their proper proportions,
when intense heat is generated and light is also given off from the
ignited carbon. The temperature of the products of combustion at this
final stage depend upon the quantity of air in dilution. Sir H. Davy
estimates this heat as greater than the white heat of metals.
In the first stages heat is absorbed, but is given out in the last.
When the chemical atoms of heat are not united in their proper
proportions, then carbonic oxide, mixed carbon and hydrogen, and other
combustible gases escape invisibly, with a corresponding loss of heat
from the fuel.
When the proper union takes place, then only steam, carbonic acid and
nitrogen, all of which are incombustible, escape.
The principal products, therefore, of perfect combustion are: steam,
invisible and incombustible; carbonic acid, invisible and incombustible.
The products of imperfect combustion are: carbonic oxide, invisible but
combustible; smoke, partly invisible and partly incombustible.
Steam is formed from the hydrogen gas given out by the coals combining
with its equivalent of oxygen from the air. Smoke is formed from
the hydrogen and carbon which have not received their respective
equivalents of oxygen from the air, and thus pass off unconsumed. The
color of the smoke depends upon the carbon passing off in its dark,
powdery state.
The heat lost is not dependent upon the amount of carbon alone, but
also upon the invisible but combustible gases, hydrogen and carbonic
oxide; so that while the color may indicate the amount of carbon in the
smoke, it does not indicate the amount of the heat lost; hence, the
smokeless locomotive burning coke may lose more heat in this way than
that arising from the imperfect burning of coal under the stationary
engine boiler.
A practical and familiar instance of imperfect combustion is exhibited
when a lamp smokes and the unconsumed carbon is deposited all about in
the form of soot. When the evolving or disengagement of the carbon is
reduced by lowering the wick to meet the supply of oxygen, the carbon
is all consumed and the smoke ceases. What takes place in a lamp also
occurs in a furnace, so that the proper supply of air is a primary
thing, relating to economy, both as regards its quantity and its mode
of admission to a fire.
The economical generation of heat is one thing, the use made of
that heat afterwards is another. Combustion may be perfect, but the
absorption of heat by a boiler may be inferior.
The chief agents operating in the furnace are carbon, hydrogen and
oxygen, and their union in certain proportions produces other bodies,
as water or steam, carbonic acid, besides others of less practical
importance.
OXYGEN is an invisible gas, has no smell, and remains permanently in
receptacles, unchanged by time. It can be obtained in an experimental
quantity by heating the chlorate of potash, and collecting the gas
given off in a bladder or jar. It is a trifle heavier than common
air, _i.e._, 1.106 times and a cubic foot at 32° temperature weighs
1.428 ounces. It is one of the most abundant bodies in nature, and is
combined with many others in a great variety of ways.
CARBON is one of the most interesting elementary substances in
nature. It is combustible and forms the base of charcoal, and enters
largely into mineral coal. It is a mineral capable of being reduced to
a feathery powder, and is found in many different forms. It is obtained
by various processes: from oil lamps as lamp-black; from coal as coke,
and from wood as charcoal; the mineral particles of carbon in a state
of combustion render flame luminous from either gas, oil or candles.
Carbon unites with iron to form steel, and with hydrogen to form the
common street gas. Carbon is considered as the next most abundant body
in nature to oxygen. In the furnace the carbon of the fuel unites
with the oxygen of the air to produce heat; if the supply of air is
correctly regulated, there will be perfect combustion, but if the
supply of air be deficient, combustion will be imperfect.
HYDROGEN is an invisible gas, and the lightest known body in the world,
being many times lighter than oxygen. It is combustible and gives out
much heat. In our gas establishments it is made in large quantities and
combined with carbon for illuminating streets, shops and dwellings. It
is the source of all common flame. When united with sulphur in coal
mines it becomes explosive. By passing a current of steam through a hot
iron tube partly filled with filings, hydrogen gas is given off and
burns with a pale yellow flame.
The more hydrogen, therefore, there is in the fuel, the greater in
general is its heating power. But it must be borne in mind that the
element of hydrogen is, nevertheless, to a greater or less degree
neutralized by the other element, oxygen, when it is present as a
constituent of the fuel; since the affinity of hydrogen for oxygen is
superior to that of carbon, and the oxygen saturated with hydrogen is
converted into steam and rises in this form from the fuel bed without
producing heat. Thus it is that the more oxygen there is in the fuel
the less is its power for developing heat by combustion.
NITROGEN is also an elementary body. It neither supports life nor
combustion; it is lighter than air and has no taste or smell. One cubic
foot at 32° temperature weighs a trifle less than one ounce.
SULPHUR is also an elementary body, of a yellow color, brittle, does
not dissolve in water, is easily melted, and inflammable. It is also
called brimstone or _burnstone_, from its great combustibility. It
burns with a blue flame, and with a peculiar, suffocating odor.
CARBONIC ACID GAS is formed by the burning of sixteen parts of oxygen
and six parts of carbon. Its specific gravity is 1.529; it is fatal to
life, and it also extinguishes fire.
CARBONIC OXIDE is a colorless, transparent, combustible gas, which
burns with a pale blue flame, as may be seen at times on opening a
locomotive fire-box door. Its presence in a furnace is evidence of
imperfect combustion from a deficient supply of air, as it indicates
that only eight parts of oxygen instead of sixteen parts have united
with six parts of carbon.
TABLE.
The following table exhibits the comparative amounts of water which can
be, under perfect conditions, evaporated from the substances named:
One pound burned. Water evaporated.
Hydrogen 64.28
Carbon (average of several experiments) 14.77
Carbonic Oxide 4.48
Sulphur 4.18
Alcohol 13.40
Oil gas 22.11
Turpentine 20.26
The last four substances are compounds, and the last three consist
almost wholly, or chiefly of carbon and hydrogen. The total heating
power of average coal is, it may be noted to advantage, about 12.83
pounds of water upon the same conditions as above described. Hydrogen,
it is seen, stands pre-eminently at the head of the list for heating
power, represented by the evaporation of 64-1/4 pounds of water, whilst
carbon, the next in order, and the staple combustible element in fuel,
has only a heating power of 14-3/4 pounds of water.
HEAT-PROOF AND ORNAMENTAL PAINTS.
Steam pipes, boiler fronts, smoke connections and iron chimneys are
often so highly heated that the paint upon them burns, changes color,
blisters and often flakes off. After long protracted use under varying
circumstances, it has been found that a silica-graphite paint is well
adapted to overcome these evils. Nothing but _boiled linseed oil_ is
required to thin the paint to the desired consistency for application,
no dryer being necessary. The paint is applied in the usual manner with
an ordinary brush. The color, of course, is black.
Another paint, which admits of some variety in color, is made by mixing
soapstone, in a state of fine powder, with a quick-drying varnish
of great tenacity and hardness. This will give the painted object
a seemingly-enameled surface, which is durable and not affected by
heat, acids, or the action of the atmosphere. When applied to wood it
prevents rotting, and it arrests disintegration when applied to stone.
It is well known that the inside of an iron ship is much more severely
affected by corrosion than the outside, _and this paint has proven
itself to be a most efficient protection from inside corrosion_. It is
light, of fine grain, can be tinted with suitable pigments, spreads
easily, and takes hold of the fibre of the iron or steel quickly and
tenaciously.
Turpentine well mixed with black varnish also makes a good coating for
iron smoke pipes.
Much brighter and more pleasant appearing engine rooms can be made by
making the surfaces white. Lime is a good non-conductor of heat, and
it has the further quality of protecting iron from rust, so it would
appear that whitewash was as good a material with which to cover boiler
fronts, smoke stacks, steam pipes, etc., as any other substance.
To prepare whitewash for this purpose it is only necessary to add a
little salt or glue to the water used for dissolving the lime, as
either of these substances will make it stick readily and it cannot
afterward be easily rubbed off; but perhaps the best way to prepare
the whitewash would be to boil a pound of rice until it has become the
consistency of starch, all of the solid particles having been broken up
by boiling, and add this solution to the solution of lime in water.
This last preparation is also very good for outside work, for after it
has been applied and has an opportunity to dry, no amount of rain will
wash it off and its appearance is almost equal to white paint, and no
amount of heat ordinarily met with will discolor it, although the heat
of the fire box doors, if it was applied in such place, would give it a
brownish cast of color. Even the brick setting of a boiler looks very
much better when nicely whitewashed than when of its natural color,
and if the ceiling and walls of the boiler room are also whitewashed
the effect is quite pleasing, more healthful and conduces greatly to
cleanliness.
Any engineer who tries this, renewing the whitewash as frequently as he
would paint, will give this plan of painting pipes and boiler front the
preference over the use of any kind of black paint.
PRESSURE RECORDING GAUGE.
This device is an ingenious mechanism actuated by clock work and the
varying pressures of steam formed within the boiler; it records the
time and the pressure upon a revolving roll of paper and preserves an
accurate account of the varying conditions which have existed within
the boiler.
[Illustration: Fig. 105.]
The advantages derived from its use may be thus summarized: 1, It is a
monitor constantly teaching the fireman to be careful to maintain an
equal pressure of steam. 2, This uniform steam made possible by the use
of the gauge is productive of the greatest possible economy. 3, The
even strain maintained insures a long life to the boiler and a minimum
of repairs. 4, It is the vindication of an attentive and careful
fireman and allows him due credit for his skill and faithfulness, which
is too often ill appreciated for lack of a reliable record.
Although described as a boiler room fixture, where it is frequently
found in position, the proper place for this admirable device is in
the steam user’s office, thus establishing _a nerve connection_,
between engineer and owner, relating to the safety and economy of the
power-plant to their mutual great advantage.
HORSE POWER AS APPLIED TO BOILERS.
By general agreement a horse power as applied to steam boilers is
thirty (30) pounds of feed water at a temperature of 100 degrees Fahr.
converted into steam in 1 hour at 70 pounds gauge pressure.
The standard is all that can be asked because the same test will
determine two things; first the steam making capacity of the boiler and
second its evaporative efficiency, which is all that is necessary to
know in determining the commercial rating of boilers.
But it is a fact that, without an engine attached, there is no
such thing as calculating the horse power of a boiler upon general
principles. A well constructed engine with a given pressure of steam
upon a piston of a given area and moving at a certain velocity in feet
per minute, will always and under all conditions develop the same power
so long as the boiler is able to furnish a sufficient quantity of steam
to keep up that pressure; and it matters not whether the steam is taken
from a boiler rated at 60 horse power or 30.
An evidence of the fact that there is no standard rule for calculating
the horse power of boilers that can be depended upon, is that no two
engine builders send out the same sized boilers with the engine of the
same rated power. Experience has taught them that to furnish steam
sufficient to work their engines up to their ratings that a certain
sized boiler is required, and what would be considered 30 horse power
by one manufacturer might be considered 35 or more by another—the
difference being in the economy of the engine of using the steam, and
not in the boiler for making it.
Then, again, a boiler that might furnish a sufficient quantity of steam
to work a certain type of engine up to 40 horse power without forcing
the fire might, with another style of engine, in order to generate
the same power and perform the same duty, require to be forced beyond
the limits of safety or economy. Therefore, considering the varying
conditions under which all steam boilers are placed, there is no such a
thing as any reliable standard rule for calculating the horse power of
boilers, but only an approximate one at the best.
Hence it is best to select an engine of a certain power, and then let
the same manufacturers furnish a boiler to correspond with it; and so
long as the two are adapted to each other and the boiler of sufficient
capacity to work the engine up to its full ratings, it matters but
little whether the boiler figures the same horse power or not.
It has been found in practice that it is not good economy to carry
pressure higher than eighty pounds in single cylinder automatic cut off
engines.
As pressures increase, it becomes possible to use more economical
engines, reducing water consumption per horse power per hour, thus
requiring a smaller amount of heating surface and grate surface, that
is to say, a smaller boiler and furnace for a given power.
For pressure between eighty and one hundred and twenty pounds, the
compound engine gives the best results, while for higher pressures
triple and quadruple expansion engines are the most economical.
RULE FOR ESTIMATING HORSE POWER OF HORIZONTAL TUBULAR STEAM BOILERS.
Find the square feet of _heating surface_ in the shell, heads and
tubes, and divide by 15 for the nominal horse power.
The office of a boiler is to make steam and its real efficiency or the
measure of its utility to the purchaser is measured by the amount of
water it can turn into steam in a certain length of time and the amount
of coal it requires to do this work.
An ordinary 54″×16′ boiler with forty 4″ tubes, 25 sq. ft. of grate
surface and 800 sq. ft. of heating surface, in a general way is a 75 h.
p. boiler, but good practice will get from it 100 h. p., and the very
best modern engines 200 h. p.
BOILER SETTING.
The method, either ill or good in which steam boilers are “set” or
arranged in their brick work and connections, will vary the quantity of
fuel used by as much as one-fifth; hence the importance of knowing the
correct principles upon which the work should be done.
[Illustration: Fig. 106.]
The portion of the steam plant called “the boiler” is composed of two
parts—the boiler and _the furnace_, and the latter may be considered a
part of the “setting” as it is mainly composed of brick work.
Two kinds of brick are used in boiler setting—the common brick
for walls, foundations and backing to the furnace, and so-called
fire-brick, which should be laid at every point where the fire operates
directly upon the furnace and passages.
Fire brick should be used in all parts of the setting which are exposed
to the hot gases. It is better to have fire brick lining tied in with
red brickwork, unless the lining is made 13-1/2 inches thick, when it
can be built up separate from outside walls. This arrangement will
require very heavy walls. As usual, but 9 inches fire brick lining is
used in the fireplace and 4-1/2 inches behind the bridge wall. Joints
in the fire brick-work should be as thin as possible.
Fig. 106 represents some of the different shapes in which fire brick
are made to fit the side of the furnace. They are called by special
names indicated by their peculiar form, circle-brick, angle-brick,
jamb-brick, arch-brick, etc. The common fire brick are 9″×4-1/2″×2-1/2″
in size, as shown in the figure.
The peculiar quality in fire bricks is their power to resist for a long
time the highest temperatures without fusion; they should be capable of
being subjected to sudden changes of temperature without injury, and
they should be able to resist the action of melted copper or iron slag.
Fire brick are cemented together with fire clay which is quite unlike
the ordinary mortar which is most suitable for common brick.
The setting as well as construction of boilers differs greatly, but in
all the end to be sought for is _a high furnace heat_, with as little
_waste as possible, at the chimney end_. To attain this there must
be (1) a sufficient thickness of wall around the furnace, including
the bridge, to retain as nearly as may be every unit of heat. (2) A
due mixture of air admitted at the proper time and temperature to the
furnace. (3) A proportionate area between the boiler and the surface of
the grates for the proper mixing of the gases arising from combustion.
(4) A correct proportion between the grate surface, the total area of
the tubes and the height and area of the chimney.
The principal parts and appendages of a furnace are as follows:
_The furnace_ proper or fire box, being the chamber in which the
solid constituents of the fuel and the whole or part of its gaseous
constituents are consumed.
_The grate_, which is composed of alternate bars and spaces, to support
the fuel and to admit the air.
_The dead-plate_, that part of the bottom of the furnace which consists
of an iron plate simply.
_The mouth piece_, through which the fuel is introduced and often some
air. The lower side of the mouth piece is the dead plate.
_The fire door_: Sometimes the duty of the fire door is performed by a
heap of fuel closing up the mouth of the furnace.
_The furnace front_ is above and on either side of the fire door.
_The ash pit._ As a general rule the ash pit is level, or nearly so,
with the floor on which the fireman stands, and as for convenient
firing, the grate should not be higher than 28 to 30 inches, the depth
of ash pit is thereby determined.
_The ash pit door_ is used to regulate the admission of air.
_The bridge wall._
_The combustion or flame chamber._
[Illustration: Fig. 107.]
[Illustration: Fig. 108.]
[Illustration: Fig. 109.]
[Illustration: Fig. 110.]
The arrangement of the space behind the bridge wall is found usually to
be in some one of the following forms: Level from bridge wall to back
(Fig. 107). A square box, depth ranging from 15 inches to 6 feet (Fig.
108). A gradual rise from bridge to back end of boiler, where only six
inches is found and generally circular in form (Fig. 109). A gradual
slope toward back, leaving a distance of about 36 inches from boiler
(Fig. 110).
The advocates of Fig. 107 claim that the office of the flame is to
get into as close contact with the bottom as possible, and this form
compels the flame to do so. In burning soft coal this form is found to
soot up the bottom of the boiler very badly.
Fig. 108 is followed more extensively than any other, the variations
being the depth of chamber; with depth generally from 36 to 40 inches.
Fig. 109 has nothing to commend it, except in cases where bridge is too
low.
Fig. 110 is followed a great deal and gives very good satisfaction.
This form allows for the theory of combustion, namely, the expansion of
the gases after leaving bridge wall.
Space behind the bridge wall should be enlarged, as it will reduce the
velocity of fire gases, and thus have them give up more of their heat
to the boiler.
The bridge wall should not be less than 18 inches at bottom, but may be
tapered off toward top to 9 or 13 inches.
SETTING OF WATER TUBE BOILERS.
On page 67, Fig. 26, is exhibited a steam boiler with inclined tubes.
The setting in this style of boilers is as follows:
A brick wall is laid for the front with suitable openings for the doors
of the furnace and ash pit, and protected on the outside by a front of
cast iron, and on the inside by a lining of fire brick.
At the back of the grates a bridge wall is run up to the bottom of the
inclined water tubes, so that the hot gases that arise over it must
circulate among the tubes.
A counter wall is laid on an incline from the top of the tubes to the
back of the drum. This is laid on perforated plates or bars and is
covered with fire brick. A wall is also built at the lower and back end
of the tubes to carry them.
Back of the whole is the outer wall with openings for giving access
to the tubes and smoke chambers. Side walls are raised to enclose the
same and are arched at the top to come nearly in contact with the drum,
which is carried partly by brackets and partly by the connections to
the tubes.
POINTS RELATING TO BOILER SETTING.
Long and heavy boilers are best suspended from two beams or girders by
two or three bolts at each end. Boilers over 40 feet long should have
three or even four sets of hangers, as the case may require.
Side brackets resting on masonry may be used for short boilers. If used
on long boilers, side plates or expansion rollers should be used at
one end of boiler. There ought to be not more than two brackets on one
side, so divided that the distance between them is about three-fifths
of the total length of the boiler, or the distance from ends of boiler
to center of bracket is equal to one-fifth the length of boiler.
The side walls in boiler-setting should not be less than twenty inches
with a two inch air space; the rear wall may vary from 12 to 16 inches
according to the size of the boiler; the front wall 9 inches and the
bridge wall may be from 18 to 24 and perfectly straight across the rear
of the furnace. If the boilers are supported by side walls, the outside
walls should be not less than 13 inches thick and have pilasters where
the boiler is resting.
Flues touching the boiler above the water space should be emphatically
condemned.
Unless the boiler walls are very heavy, they should be stayed by cast
or wrought iron bunch stays, held together by rods at tops and bottoms.
It is dangerous to have large spaces in which gases may collect for
sudden ignition, producing the so-called “back draft.”
Connections between the rear end of the boiler and brickwork is best
made with cast-iron plates or fire-brick, suspended, when boilers are
suspended, as the expansion and contraction will destroy an arch in
a short time. If resting on mud-drum stand, this connection can be
arched, as in this case the rear end of boiler will remain stationary.
If the draughts from the different boilers come in the same direction,
or nearly so, no special provision is necessary, but if the draught
enters from directly opposite directions a centre wall should be
provided.
An advantage claimed for water in the ash pit is: by the dropping
of hot ashes and cinders from the grate into the water, steam is
generated, which, in passing through the hot coal lying on the grate,
is there divided into oxygen and hydrogen, thus helping the combustion.
A dry brick will absorb a pound of water, and it is the water in the
mortar that causes it to set, and harden. To prevent this loss of the
water of crystalization, and give it time to harden and adhere to the
brick, the brick must be well saturated with water, before they are
laid.
Whenever steam is allowed to come in contact with mortar or cement an
injurious effect is produced. The action of the steam is much more
rapid than that of air and water, or water alone, when in abundance,
as the effect of the steam in every case is to soften the mortar and
penetrate to a greater depth than water could possibly do.
The distance between the rear head of the boiler and brickwork should
not be less than 12 inches.
In setting steam boilers, allowance must be made for the expansion
and contraction of the structure and this is usually done by placing
rollers under the rear lug or side bearing of the boiler. Care should
be exercised that the boiler rests are always in good condition so that
they may move freely and not place the boiler in any danger of sticking
and buckling.
KINDLING A FURNACE FIRE.
In kindling a coal fire in a furnace the phosphorus of a match inflames
at so low a temperature (150 degrees Fahr.) that mere friction ignites
it, and in burning (combining with oxygen of the air) it gives out heat
enough to raise the sulphur of the match to the temperature of ignition
(500 degrees Fahr.), which, combining in its turn with the oxygen of
the atmosphere, gives out sufficient heat to raise the temperature
of the wood to the point of ignition (800 degrees Fahr.), and at
this temperature the wood combines with oxygen supplied by the air,
giving out a temperature sufficient to raise the coal to the point
of ignition (1000 degrees Fahr.), and the coal then combines with the
free oxygen of the air, the ensuing temperature in the furnace varying,
according to circumstances, from 3000 degrees to 4000 degrees Fahr.
Thus we see that the ignition of the coal is the last of a series of
progressive steps, each increasing in temperature.
And in each step it will be noted that a combination of oxygen is the
essential connecting link and _that the oxygen is supplied in each
instance at the same average temperature_—this fact contains a “point”
relating to supplying furnaces with so called “hot air.”
SAWDUST FURNACE.
[Illustration: Sawdust Furnace Section]
Referring also to page 33 for information relating to the burning of
sawdust and shavings S. S. Ingham, _in the Stationary Engineer_, says
upon this important matter:
“Regarding a furnace for burning sawdust, I submit the accompanying
cuts. I have built numbers of these oven furnaces for burning this fuel
in the south, and all have given excellent results. The dimensions
are for 60″ × 16′ return tubular (4″ tubes) boiler with stack 50 per
cent. greater area than the flues; a good draft is necessary.” It will
be understood that the upper cut is designed to show end view of the
furnace whose side is shown in sectional view at the bottom of the page.
[Illustration: Sawdust Furnace Side View]
GAS PIPE.
[Illustration: Fig. 111.]
[Illustration: Fig. 112.]
PIPES AND PIPING.
Next in importance after the skill necessary for the steam generator
and the engine, is the proper arrangement and care and management of
the pipes and valves belonging to a steam plant.
It is the first thing an engineer does in taking charge of a new place,
to ascertain the exact course and operation of the water, steam, drain
and other pipes.
Examiners for licensing marine and land engineers base their questions
much more to ascertain the applicant’s knowledge of piping than is
generally known; hence the importance of the “points” in the succeeding
pages relating to this subject.
Pipes are used for very many purposes in connection with the boiler
room, and of course vary in size, in material and in strength,
according to the purposes for which they are designed. There are pipes
for conveying and delivering illuminating gas; pipes for conveying and
delivering drinking water, and for fire purposes; pipes for draining
and carrying off sewage and surface water; pipes for delivering hot
water under high pressure, for heating purposes and power; pipes
for delivering live steam under pressure, for heating purposes and
power; pipes for delivering compressed air, for purposes of power and
ventilation; pipes for conveying mineral oils, etc.
In Figs. 111, 112 113 and 114 are given approximate sizes of gas
pipe and boiler tubes, taken from the catalogue of one of the oldest
steamfitting establishments in the country. It will be observed that
the size of gas pipe is computed from the internal diameter, while
boiler tubes are estimated from the outside: thus, 3 in. gas pipe has
an external diameter of 3-1/2 inches, while 3 in. boiler tubes have an
outside diameter of 3 inches only. It may be noted that boiler-tubes
are made much more accurately as to size than gas pipe; this is
especially true of the outside surfaces which are much smoother in one
case than in the other.
BOILER TUBES.
[Illustration: Fig. 113.]
[Illustration: Fig. 114.]
SURFACES AND CAPACITIES OF PIPES.
---------------+-----+-----+------+------+------+------
SIZES OF PIPES.| 1/2 | 3/4 | 1 | 1-1/4| 1-1/2| 2
| in. | in. | in. | in. | in. | in.
---------------+-----+-----+------+------+------+------
1. Outside | | | | | |
circumferences | | | | | |
of pipes in | | | | | |
inches |2.652|3.299|4.136 | 5.215| 5.969|7.461
| | | | | |
2. Length of | | | | | |
Pipe in feet to| | | | | |
give a square | | | | | |
foot of outside| | | | | |
surface |4.52 |3.63 |2.90 | 2.30 | 2.01 |1.61
| | | | | |
3. Number of | | | | | |
square feet of | | | | | |
outside surface| | | | | |
in ten lineal | | | | | |
feet of Pipe |2.21 |2.74 |3.44 | 4.34 | 4.97 |6.21
| | | | | |
4. Cubic in. | | | | | |
of internal | | | | | |
capacity in | | | | | |
ten lineal feet| | | | | |
of pipe |36.5 |63.9 |103.5 | 179.5| 244.5|402.6
| | | | | |
5. Weight in | | | | | |
lbs. of water | | | | | |
in ten lineal | | | | | |
feet of pipe | 1.38| 2.31| 3.75 | 6.5 | 8.8 | 14.6
---------------+-----+-----+------+------+------+------
---------------+-----+-----+------+------+------+------
SIZES OF PIPES.|2-1/2| 3 | 3-1/2| 4 | 4-1/2| 5
| in. | in. | in. | in. | in. | in.
---------------+-----+-----+------+------+------+------
1. Outside | | | | | |
circumferences | | | | | |
of pipes in | | | | | |
inches |9.932|10.99| 12.56| 14.13| 15.70|17.47
| | | | | |
2. Length of | | | | | |
Pipe in feet to| | | | | |
give a square | | | | | |
foot of outside| | | | | |
surface |1.32 |1.09 | .954 | .849 | .763 | .686
| | | | | |
3. Number of | | | | | |
square feet of | | | | | |
outside surface| | | | | |
in ten lineal | | | | | |
feet of Pipe |7.52 |9.16 | 10.44| 11.78| 13.09|16.56
| | | | | |
4. Cubic in. | | | | | |
of internal | | | | | |
capacity in | | | | | |
ten lineal feet| | | | | |
of pipe |573.9|886.6|1186.4|1527.6|1912.6|2398.8
| | | | | |
5. Weight in | | | | | |
lbs. of water | | | | | |
in ten lineal | | | | | |
feet of pipe | 20.8| 32.1| 43.6 | 55.4 | 69.3 | 86.9
---------------+-----+-----+------+------+------+------
Pipe manufactured from double thick iron is called X-strong pipe, and
pipe made double the thickness of X-strong is known as XX-strong pipe.
Both X-strong and XX-strong pipe are furnished plain ends—no threads,
unless specially ordered.
The table “Data relating to iron pipe” will be found especially useful
to the engineer and steam fitter. The size of pipes referred to in
the table range from 1/8 to 10 inches in diameter. In the successive
columns are given the figures for the following important information:
1. Inside diameter of each size.
2. Outside diameter of each size.
3. External circumference of each size.
4. Length of pipe per square foot of outside surface.
5. Internal area of each size.
6. External area of each size.
7. Length of pipe containing one cubic foot.
8. Weight per foot of length of pipes.
9. Number of threads per inch of screw.
10. Contents in gallons (U. S. measure) per foot.
11. Weight of water per foot of length.
DATA
RELATING TO IRON PIPE.
+---------+---------+--------------+----------+---------+---------+
| | | | Length of| | |
| Inside | Outside | External | Pipe per |Internal |External |
|Diameter.|Diameter.|Circumference.| sq. ft. | Area. | Area. |
| | | |of Outside| | |
| | | | Surface. | | |
+---------+---------+--------------+----------+---------+---------+
| Inches. | Inches. | Inches. | Feet. | Inches. | Inches. |
| 1/8 | .40 | 1.272 | 9.44 | .012 | .129 |
| 1/4 | .54 | 1.696 | 7.075 | .049 | .229 |
| 3/8 | .67 | 2.121 | 5.657 | .110 | .358 |
| 1/2 | .84 | 2.652 | 4.502 | .196 | .554 |
| 3/4 | 1.05 | 3.299 | 3.637 | .441 | .866 |
| 1 | 1.31 | 4.134 | 2.903 | .785 | 1.357 |
| 1-1/4 | 1.66 | 5.215 | 2.301 | 1.227 | 2.164 |
| 1-1/2 | 1.9 | 5.969 | 2.01 | 1.767 | 2.835 |
| 2 | 2.37 | 7.461 | 1.611 | 3.141 | 4.430 |
| 2-1/2 | 2.87 | 9.032 | 1.328 | 4.908 | 6.491 |
| 3 | 3.5 | 10.996 | 1.091 | 7.068 | 9.621 |
| 3-1/2 | 4. | 12.566 | .955 | 9.621 | 12.566 |
| 4 | 4.5 | 14.137 | .849 | 12.566 | 15.904 |
| 4-1/2 | 5. | 15.708 | .765 | 15.904 | 19.635 |
| 5 | 5.56 | 17.475 | .629 | 19.635 | 24.299 |
| 6 | 6.62 | 20.813 | .577 | 28.274 | 34.471 |
| 7 | 7.62 | 23.954 | .505 | 38.484 | 45.663 |
| 8 | 8.62 | 27.096 | .444 | 50.265 | 58.426 |
| 9 | 9.68 | 30.443 | .394 | 63.617 | 73.715 |
| 10 | 10.75 | 33.000 | .355 | 78.540 | 90.792 |
+---------+---------+--------------+----------+---------+---------+
+---------+----------+----------+----------+-----------+----------+
| | Length | Weight | No. of | Contents |Weight of |
| Inside | of Pipe | per ft. | Threads | in |Water per |
|Diameter.|containing| of |per inch |Gallons[A] | foot of |
| |one Cubic | Length. |of Screw. |per foot. | Length. |
| | Foot. | | | | |
+---------+----------+----------+----------+-----------+----------+
| Inches. | Feet. | Lbs. | | | Lbs. |
| 1/8 | 2500. | .24 | 27 | .0006 | .005 |
| 1/4 | 1385. | .42 | 18 | .0026 | .021 |
| 3/8 | 751.5 | .56 | 18 | .0057 | .047 |
| 1/2 | 472.4 | .84 | 14 | .0102 | .085 |
| 3/4 | 270. | 1.12 | 14 | .0230 | .190 |
| 1 | 166.9 | 1.67 | 11-1/2 | .0408 | .349 |
| 1-1/4 | 96.25 | 2.25 | 11-1/2 | .0638 | .527 |
| 1-1/2 | 70.65 | 2.69 | 11-1/2 | .0918 | .760 |
| 2 | 42.36 | 3.66 | 11-1/2 | .1632 | 1.356 |
| 2-1/2 | 30.11 | 5.77 | 8 | .2550 | 2.116 |
| 3 | 19.49 | 7.54 | 8 | .3673 | 3.049 |
| 3-1/2 | 14.56 | 9.05 | 8 | .4998 | 4.155 |
| 4 | 11.31 | 10.72 | 8 | .6528 | 5.405 |
| 4-1/2 | 9.03 | 12.49 | 8 | .8263 | 6.851 |
| 5 | 7.20 | 14.56 | 8 | 1.020 | 8.500 |
| 6 | 4.98 | 18.76 | 8 | 1.469 | 12.312 |
| 7 | 3.72 | 23.41 | 8 | 1.999 | 16.662 |
| 8 | 2.88 | 28.34 | 8 | 2.611 | 21.750 |
| 9 | 2.26 | 34.67 | 8 | 3.300 | 27.500 |
| 10 | 1.80 | 40.64 | 8 | 4.081 | 34.000 |
+---------+----------+----------+----------+-----------+----------+
[Footnote A: The Standard U. S. gallon of 231 cubic inches.]
The division of process in the manufacture of pipe, takes place at
1-1/4 inch, 1-1/4 inch and smaller sizes being called butt-welded pipe,
and 1-1/2 inch and larger sizes being known as lap-welded pipe; this
rule holds good for standard, X-strong and XX-strong.
JOINTS OF PIPES AND FITTINGS.
The accompanying illustrations represent certain joints, couplings and
connections used in steam and hot water heating systems.
[Illustration: Fig. 115.]
[Illustration: Fig. 116.]
For many years in the matter of pipe joints there has been little
change. The cast-iron hub and spigot joint, Fig. 115, caulked with iron
borings, is probably the oldest kind of joint. This is still generally
adopted in hot water heating of a certain class, and was formerly used
with low-pressure steam. A fairly regular smooth internal service
is obtained, and once made tight is very durable. Cast-iron flanged
pipes have also been a long time in use. These joints are made with a
wrought-iron ring gasket, wrapped closely with yarn, Fig. 116, which
is sometimes dipped in a mixture of red and white lead. It is placed
between the flanges, it being of such a diameter as to fit within the
bolts by which the joint was screwed up and a nest or iron joint, B B,
caulked outside the annular gasket between the faces of the flanges.
The next step in cast-iron flange pipe joints was the facing or turning
up of the flanges and the use of a gasket of rubber, copper, paper or
cement, with bolts for drawing the faces together. These joints for
cast-iron pipes have not been changed excepting for some classes of
work where a lip and recess, Fig. 117, formed on opposite flanges,
which makes the internal surfaces smooth and aid in preventing the
gaskets from being blown out.
[Illustration: Fig. 117.]
[Illustration: Fig. 118.]
[Illustration: Fig. 119.]
[Illustration: Fig. 120.]
The introduction of wrought iron welded pipes has diminished the use
of cast-iron pipes for many purposes, especially in heating apparatus
and other pipe systems. Its advantages are lightness, the ease with
which various lengths can be obtained and its strength. In wrought-iron
pipe work the general practice in making joints between pipes is a
wrought-iron coupling, Fig. 118, with tapered threads at both ends.
The pipes do not meet at their ends, and a recess of about 3/4 inch
or more long by the depth of the thickness of the pipes is left at
every pipe end. A similar tapered thread is used in connecting the
cast-iron fittings, elbows, tees, etc., Fig. 119, to the pipe, and a
large recess is necessary in each fitting to allow for the tapping of
the threads. Thus the inside diameter of the fitting is larger by 1/8
inch than the outside diameter of the pipe, and the internal projection
of the thickness of the pipe and that of the thread of the fitting
increases materially the friction due to the interior surfaces of pipe
and fitting. This class of joint requires care in the tapping of the
fittings and in the cutting of tapered threads on the pipes; much
trouble is caused by an inaccurately cut thread, as it may throw a line
of pipes several inches out of place and put fittings and joints under
undue and irregular strains.
[Illustration: Fig. 121.]
[Illustration: Fig. 122.]
The right and left threaded nipple, Fig. 119, is used as a finishing
connection joint and between fittings. Space equal to the length of the
two threads is required between the two fittings to be connected in
order to enter the nipple, and one or both fittings should be free to
move in a straight line when the nipple is being screwed up. To make
up this joint time and care are necessary. The right threaded end on
nipple should be first firmly screwed with the tongs or wrench into the
right threaded end of fitting, then slacked out and screwed up again
by hand until tight, when it is screwed back by hand, at the same time
counting the number of threads it has entered by hand. The same is done
with the left threaded end of nipple and fitting. If the right and left
threads of nipple have counted the same number of threads, each thread,
when making the joint up, should enter the fittings at the same time
if possible, and particular care must be taken that the fittings are
exactly opposite, to facilitate catching on, prevent crossing threads,
and that no irregular strain comes on the nipple while being screwed up.
In screwing up these nipples the coupling has to be turned with flats
on the external surface to fit an internal wrench: in such cases the
thread on nipple has one continuous taper. These special couplings
are marked with ribs on the outside to distinguish them. Fig. 120
represents another joint in wrought-iron piping known as the “union”
composed of three pieces of the washer. Unions are also made with
ground joints, and the washer dispensed with. Radiator valves are now
generally connected by them, but if the hole in the radiator is not
tapped accurately, the union when drawn up will not be tight, or if
tight, the valve will not be straight.
Fig. 121 shows right and left threaded nipple connecting elbow and tee
with wrought-iron pipes.
The flange union, Fig. 122, is another joint generally used on
wrought-iron pipes above 4 or 5 inches in diameter in making
connections to valves, etc., and on smaller pipes in positions where it
is a convenient joint. This joint consists of two circular cast-iron
flanges with the requisite number of holes for bolts, and central hole
tapped tapered to receive thread of pipe. The abutting faces of the
flanges are generally turned and the holding bolts fitted into the
holes.
STEAM AND HOT WATER HEATING.
The heating by means of pipes through which are conveyed hot water
and steam is a science by itself and yet one claiming some degree of
familiarity by all engineers, steam users, and architects.
[Illustration: Fig. 123.]
[Illustration: Fig. 124.]
In practice it requires a knowledge of steam, air and temperatures,
of pressure and supply; a familiarity with heat and heating surfaces
and with all contrivances, appliances and devices that enter into the
warming and ventilation of buildings. So long as factories, public and
private buildings are erected, so long will warming and ventilation
keep progress with steam engineering and remain a part of the general
mechanical science required of the supervisory and practical engineer.
In what is called _the system of open circulation_, a supply main
conveys the steam to the radiating surfaces, whence _a return main
conducts the condensed water either into an open tank for feeding the
boiler, or into a drain to run to waste_, the boiler being fed from
some other source; the system of what is called _closed circulation_
is carried out either with separate supply and return mains, both of
which extend to the furthest distance to which the heat has to be
distributed, or else with a single main, which answers at once for
both the supply and the return, either with or without a longitudinal
partition inside it for separating the outward current of steam supply
from the return current of condensed water.
In either case suitable traps have to be provided on the return
main, _for preserving the steam pressure within the supply main and
radiators_. These two systems, in any of their modifications, may
also be combined, as is most generally done in any extensive warming
apparatus.
The system of closed circulation requires the boiler to be placed so
low as will allow all the return pipes to drain freely back to it above
its water-level. This condition has been modified mechanically by the
automatic “trap,” a device frequently employed for lifting from a lower
level, part or all of the condensed water, and delivering it into the
boiler; it is, in fact, a displacement pump.
The same result has been attained by draining into a closed tank,
placed low enough to accommodate all the return pipes, and made
strong enough to stand the full boiler pressure with safety, and then
employing a steam pump, either reciprocating or centrifugal, to raise
the water from this tank to the proper level for enabling it to flow
back into the boiler, the whole of the circulation being closed from
communication with the atmosphere.
[Illustration: Fig. 125.]
[Illustration: Fig. 126.]
[Illustration: Fig. 127.]
There are two systems of steam heating, known as the _direct_ and the
_indirect_ system.
Direct radiating surfaces embrace all heaters placed within a room or
building to warm the air, and are not directly connected with a system
of ventilation.
Indirect radiation embraces all heating surfaces placed outside the
rooms to be heated, and can only be used in connection with some system
of ventilation.
For warming by direct radiation, the radiators usually consist of
coils, composed of 3/4-inch and 1-inch steam pipes, which are arranged
in parallel lines and are coupled to branch tees or heads. In a
few exceptional cases, radiators of peculiar shapes are specially
constructed. In all cases the coils must have either vertical or
horizontal elbows of moderate length, for allowing each pipe to expand
separately and freely. Sometimes short lengths of pipe are coupled by
return-bends, doubling backwards and forwards in several replications
one above another, and forming what are called “return-bend coils,” and
when several of these sections are connected by branch, tees into a
compact mass of tubing, the whole is known as a “box-coil.”
Steam and Hot Water heating have long been acknowledged as altogether
most practical and economical in every way—and their universal adoption
in all the better class of buildings throughout the country is positive
proof of their superiority.
[Illustration: Fig. 128.]
[Illustration: Fig. 129.]
[Illustration: Fig. 130.]
The heat from steam is almost exactly identical with that from hot
water, and few can distinguish between the two systems when properly
erected.
They are both healthful, economical and satisfactory methods of
warming. They give no gas, dust nor smoke; are automatically regulated,
and therefore allow of an even and constant temperature throughout the
house, whatever be the condition of the weather outside.
The circulation of the steam through the warming pipes is effected
in an almost unlimited variety of ways, and the cause producing the
circulation throughout the pipes of the warming apparatus is solely
the difference of pressure which results from the more or less rapid
condensation of the steam in contact with the radiating surfaces.
A partial vacuum is formed by this difference of pressure _within
the radiating portions of the apparatus_, and the column of steam or
of water equivalent to this diminution of pressure, constitutes the
effective head producing the flow of steam from the boiler, at the
same time the return current of condensed water is determined by the
downward inclination of the pipes for the return course.
POINTS RELATING TO STEAM HEATING.
No two pipes should discharge into a T from opposite directions, thus
retarding the motion of both or one of the returning currents. This is
called “butting” and is one of the most vexatious things to encounter
in pipe fitting.
[Illustration: Fig. 131.]
[Illustration: Fig. 132.]
[Illustration: Fig. 133.]
All steam piped rooms should be frequently dusted, cleaned and kept
free from accumulation of inflammable material.
The use of the air valve is as follows: In generating steam from cold
water all the free air is liberated and driven off into the pipe, with
the air left in them, all of which is forced up to the highest point
of the coils or radiators, and compressed equal to the steam pressure
following it. Now, by placing a valve or vent at the return end of the
pieces to be heated, the air will be driven out by the compression. Why
the vent is placed at the return is, that the momentum of the steam, it
being the lightest body, will pass in the direction of it, falling down
into the return as it condenses, thus liberating the air. Otherwise,
should the vent not work, and the air is left in the radiator, it will
act as an air spring, and the contents of the pipes left stationary
will be the result; no circulation, no heat; and the greater steam
pressure put on, the greater the chances are of not getting any heat;
and thus a little device, with an opening no larger than a fine needle,
will start what a ton of pressure would not do in its absence.
If the drip and supply pipes are large there is very little danger of
freezing, provided suitable precautions are taken to leave the pipes
clear. They should be blown through, when left, and the steam valve
should be closed. There should also be a free chance for air to escape
in all systems of piping.
No rule can be given relating to capacity for heating pipes and
radiators which do not require to be largely modified by surroundings.
The field of steam heating would seem to be limitless—in one public
building it required recently 480,000 dollars to meet the expenditures
in this single line. As an example of warming on an extensive scale may
be taken a large office in New York, of which the following are the
particulars:
Total number of rooms, including halls and vaults. 286
Total area of floor surface. sq. ft. 137,370
Total volume of rooms. cub. ft. 1,923,590
A second example is furnished by the State Lunatic Asylum at
Indianapolis:
Length of frontage of building, more than. 2,000 lin. ft.
Total volume of rooms. 2,574,084 cub. ft.
Warming {indirect radiating surface 23,296
Apparatus {Direct 10,804
{Total 34,100 sq. ft.
Boilers {Grate area 180 sq. ft.
{Heating surface 5,863 sq. ft.
The “overhead” system of heating with steam pipes has several
advantages. 1. The pipes are entirely out of the way 2. They do not
become covered with odds and ends of unused materials. 3. If they leak
the drip fixes the exact location of place needed to be repaired. 4.
The room occupied overhead cannot be well otherwise utilized, hence in
shops the system has proved efficient.
But for offices or store rooms the overhead system is not approved of
owing to the heat beating down upon the occupants and causing headache.
When overhead heating pipes are used, they should not be hung too near
the ceiling. If the room be a high one, it is better to hang them
below, rather than above, the level of the belts running across the
room, and they should not be less than three or four feet from the
wall.
[Illustration: Fig. 134.]
It is important to protect all wood work or other inflammable material
around steam pipes from immediate contact with them, especially where
pipes pass through floors and partitions. A metal thimble should be
placed around the steam pipe, and firmly fastened on both sides of the
floor, in such a way as to leave an air space around the steam pipe.
For indirect radiating surfaces, the box coils are the forms most
used. The chambers or casings for containing them are made either of
brickwork, or often of galvanized sheet-iron of No. 26 gauge, with
folded joints. The coils are suspended freely within the chambers,
which are themselves attached to the walls containing the air inlet
flues. Besides coils of wrought iron tubes, cast-iron tablets or hollow
slabs, having vertical surfaces with projecting studs or ribs, have
been extensively used for the radiating surfaces.
As the amount of heat given off from the radiator cannot be
satisfactorily controlled by throttling the steam supply, it is usual
to divide all radiators into sections, each of which can be shut off
from the supply and return mains, separately from the rest of the
sections. This method of regulation applies to radiators for indirect
heating as well as for direct.
Vertical pipe coils, constitute a distinctive form of radiator now
largely used. In these a number of short upright 1-inch tubes, from
two feet 8 inches to 2 feet 10 inches long, are screwed into a hollow
cast iron base or box; and are either connected together in pairs by
return-bends at their upper ends, or else each tube stands singly with
its upper end closed, and having a hoop iron partition extending up
inside it from the bottom to nearly the top. The supply of steam is
admitted into the bottom casting; and the steam on entering, being
lighter than the air, ascends through one leg of each siphon pipe and
descends through the other, while the condensed water trickles down
either leg, and with it the displaced air sinks also into the bottom
box. For getting rid of the air, a trap is provided, having an outlet
controlled by metallic rods; as soon as all the air has escaped and the
rods become heated by the presence of unmixed steam, their expansion
closes the outlet.
A thorough drainage of steam pipes will effectually prevent cracking
and pounding noises.
The windward side of buildings require more radiating surface than does
the sheltered side.
When floor radiators are used, their location should be determined
by circumstances; the best situations are usually near the walls of
the room, in front of the windows. The cold air, which always creates
an indraft around the window frames, is thus, to some extent, warmed
as it passes over the the radiators, and also assists in the general
circulation.
Water of condensation will freeze quicker than water that has not been
evaporated, for the reason that it has parted with all its air and is
therefore solid.
Whatever the size of the circulating pipes, the supply and drip pipes
should be large, to insure good circulation; the drip pipes especially
so. This is also the more necessary when the pipes are exposed, or when
there is danger of freezing after the steam is shut off.
It is important to see that no blisters or ragged pipes go into the
returns, and also to make sure that the ends are not “burred in” with
a dull pipe cutter wheel so as to form a place of lodgment for loose
matter in the pipe to stop against.
[Illustration: Figs. 135-137.]
Experiments recently made on the strength of bent pipes have developed
some things not commonly known, or at least not recognized, that is,
the strain on the inside of the angles, _due to the effort of the
pipes to straighten themselves under pressure_. The problem is one of
considerable intricacy, resolvable, however, by computation, and is a
good one for practice. In the experiment referred to, a copper pipe of
6-3/4 in. bore, 3/16 in. thick, was used. The angle was 90 degrees, and
the legs about 16 in. long from the center. At a pressure of 912 pounds
to an inch, the deflection of the pipe was nearly 3/8 in., showing an
enormous strain on the inner side, in addition to the pressure.
Steam valves should be connected in such a manner that the valve closes
against the constant steam pressure.
Interesting experiments show that the loss by condensation in carrying
steam one mile is 5 per cent. of the capacity of the main, and a steam
pressure of seventy-five pounds carried in five miles of mains, ending
at a point one-half mile from the boiler house only shows a loss of
pressure of two pounds.
In steam warming it is necessary to bring the water to a boiling point
to get any heat whatever; in hot water warming, a low temperature will
radiate a corresponding amount of heat.
Never use a valve in putting in a low pressure apparatus if it is
possible to get along without it. All the valves or cocks that are
actually required in a well-proportioned low pressure apparatus are, a
cock to blow off the water and clean out the return pipes, another to
turn on the feed water. Of course the safety valves, gauge cocks, and
those to shut fire regulators and such as are a part of the boiler, are
not included in this “point.”
The most important thing in connecting the relief to return pipes is,
that it should always be carried down below the line, the same as all
vertical return pipes. In connecting the reliefs, so that the lower
opening can at any time be exposed to the steam, there will be the
difficulty of having the steam going in one direction, and the water in
another.
The relief pipe should “tap” the steam at its lowest or most depressed
points. It should always be put in at the base of all steam “risers”
taking steam to upper floors.
In leaving the boiler with main steam pipe, raise to a height that will
allow of one inch fall from the boiler to every ten feet of running
steam pipe; this is sufficient, and a greater fall or pitch will cause
the condensed water in the pipe to make at times a disagreeable noise
or “gurgling.”
The flow pipe should never start from the boiler in a horizontal
direction, as this will cause delay and trouble in the circulation.
This pipe should always start in a vertical direction, even if it
has to proceed horizontally within a short distance from the boiler.
Reflection will show that the perfect apparatus is one that carries
the flow pipe in a direct vertical line to the cylinder or tank; this
is never, or but rarely possible, but skill and ingenuity should be
exercised to carry the pipes as nearly as possible in this direction.
The flow of steam ought not to be fast enough to prevent the water of
condensation from returning freely. All the circulating pipes should be
lowest at the discharge end, and the inclination given them should not
be less than one foot in fifty.
[Illustration: Fig. 138.]
[Illustration: Fig. 139.]
[Illustration: Fig. 140.]
[Illustration: Fig. 141.]
The general rule is to lay the main pipes from the boiler so that the
pipe will drain from the boiler. Where this is done it is necessary to
have a drip just before the steam enters the circulation. This drip
is connected to a trap, or, if the condensed water is returned to the
boiler, the drip is arranged accordingly.
But it is the best practice to lay the main pipe with the lowest part
at the boiler, so that the drip will take care of itself, and not
require an extra trap, nor interfere with the return circulation.
When steam is turned into cold pipes the water of condensation gets
cold after running a short distance, and if it has to go through a
small drip pipe full of frost it will probably be frozen. Then, unless
it is followed up with a pail of hot water, the whole arrangement will
be frozen and a great many bursted pipes will result. Whenever turning
steam on in a system of very cold pipes, only one room should be taken
at a time, and a pail of hot water should be handy so that if the pipe
becomes obstructed it can be thawed immediately without damage.
When pipes become extensively frozen there is nothing to do but take
them out and put in new ones.
[Illustration: Fig. 142.]
[Illustration: Fig. 143.]
The manner in which a temperature too low to start rapid combustion
in wood in steam pipes, operates in originating a fire is by first
reducing the oxide of iron (rust) to a metallic condition. This is
possible only under certain external conditions, among them a dry
atmosphere. _Just as soon as the air is recharged with moisture, the
reduced iron is liable to regain, at a bound, its lost oxygen, and
in doing so become red hot._ This is the heat that sets the already
tindered wood or paper ablaze.
Where there is no rust there is no danger from fire with a less than
scorching temperature in the pipe or flue. Hence the necessity of
keeping steam or hot water fittings in good order.
The indirect system of heating is the most expensive to put in; as to
the cost of providing nearly double the heating surface in the coils
must be added the cost of suitable air boxes, pipes and registers. For
a large installation, this is a serious matter, although for office
warming the advantages gained on the score of healthfulness and greater
efficiency of employees much more than counterbalance the extra expense.
One horse power of boiler will approximately heat 6,000 to 10,000 cubic
feet in shops, mills and factories—dwellings require only one horse
power for from 10,000 to 20,000 cubic feet.
From seven to ten square feet of radiating surface can be heated from
_one square foot of boiler surface_, _i.e._, the heating surface of the
boiler and each horse power of boiler will heat 240 to 360 feet of
1-inch pipe.
The profession most nearly related to that of steam engineers is the
working steam fitters’ occupation. Strictly speaking, the engineer
should produce the steam, and it is the steam fitters’ place to fix
up all the steam pipes and make all the necessary connections: but
where the steam plants are small, the engineer may be steam fitter
also: hence the introduction in this work of these “Points” which are
necessary to be known for the proper care and management of any system
of steam or hot water heating.
The care and patience, the mental strain and not infrequently the
physical torture incident to fitting up a complicated pipe system
cannot adequately be set forth in words.
It is stated to be a fact, that in high pressure hot water heating the
water frequently becomes red hot, pressures of 1000 to 1200 pounds per
square inch being reached, and when the circulation of the system is
defective the pipe becomes visibly red in the dark.
Pipes under work benches should be avoided, unless there is an opening
at the back to permit the escape of the heated air, which would
otherwise come out at the front.
When both exhaust and live steam are used for heating, many engineers
prefer to use independent lines of pipe for each, rather than run
the risk of interference and waste caused by admitting exhaust and
live steam into the same system at the same time. Nevertheless, the
advantages gained by being able to increase the heating power of a
system in extremely cold weather by utilizing the entire radiating
surface for high pressure steam, are so great that it is probably
better so to arrange the system of pipes and connections that this can
be done.
Double extra heavy pipe (XX) is used for ice and refrigerating machines
(see page 246), as a general rule, makers of this class of machinery
obtain but little satisfaction in the use of the ordinary thread
joining and use special dies _with uniform taper_—both for couplings,
flanges and threading the pipe itself. They do this to protect their
reputation and guarantees.
_Welding boiler and other tubes._—The following is a good way in cases
of emergency and can be done on a common forge:
Enlarge one end of the shortest piece, and one end of the long piece
make smaller, then telescope the two about 3/4 of an inch. Next get an
iron shaft as large as will go into the tube and lay across the forge
with the tube slipped over it. _Block the shaft up so that the tube
will hang down from the top of the shaft._ By such an arrangement the
inside of the tube will be smooth for a scraper. When the tube gets to
a welding heat strike on the _end_ of the short piece first, with a
heavy hammer, then with a light and broad-faced hammer make the weld.
Borax can be used to good advantage, but it is not necessary. The next
thing is to test the tube, which can be done in the following manner:
Drive a plug in one end of the tube, stand it up on that end, and fill
it with water, if it does not leak the job is well done, if a leak
exists the welding must be again done.
SOLID-DRAWN IRON TUBES: CALCULATED BURSTING AND COLLAPSING PRESSURES.
---------+----------+---------+------------------+--------------------
| | |BURSTING PRESSURE.|COLLAPSING PRESSURE.
External | |Internal +------------------+--------------------
Diameter.|Thickness.|Diameter.|Per Square Inch of|Per Square Inch of
| | +--------+---------+---------+----------
| | |Internal| Section |External | Section
| | |Surface.|of Metal.|Surface. | of Metal.
---------+----------+---------+--------+---------+---------+----------
Inches. | Inch. | Inches. | Lbs. | Tons. | Lbs. | Tons.
1-1/4 | .083 | 1.084 | 7700 | 22.4 | 6500 | 21.7
1-3/8 | .083 | 1.209 | 6900 | 22.4 | 5800 | 21.3
1-1/2 | .083 | 1.334 | 6200 | 22.4 | 5200 | 21.0
1-3/4 | .083 | 1.584 | 5300 | 22.4 | 4300 | 20.3
2 | .083 | 1.834 | 4500 | 22.4 | 3700 | 19.7
2-1/4 | .095 | 2.060 | 4600 | 22.4 | 3600 | 19.0
2-1/2 | .109 | 2.282 | 4800 | 22.4 | 3600 | 18.3
2-3/4 | .109 | 2.532 | 4400 | 22.4 | 3100 | 17.7
3 | .120 | 2.760 | 4300 | 22.4 | 3000 | 17.0
3-1/2 | .134 | 3.232 | 4200 | 22.4 | 2700 | 15.7
3-3/4 | .134 | 3.482 | 3900 | 22.4 | 2400 | 15.0
4 | .134 | 3.732 | 3600 | 22.4 | 2100 | 14.3
4-1/2 | .134 | 4.232 | 3200 | 22.4 | 1700 | 13.0
4-3/4 | .134 | 4.482 | 3000 | 22.4 | 1600 | 12.3
5 | .134 | 4.732 | 2800 | 22.4 | 1400 | 11.7
5-1/2 | .148 | 5.204 | 2800 | 22.4 | 1200 | 10.3
6 | | 5.704 | 2600 | 22.4 | 1000 | 9.0
---------+----------+---------+--------+---------+---------+----------
VENTILATION.
The quantity of air for each minute for one person is from four to
fifteen feet—and from one-half to one foot should be allowed for each
gas jet or lamp.
Heated air cannot be made to enter a room unless means are provided for
permitting an equal quantity to escape, and the best places for such
exit openings is near the floor.
For healthful ventilation the indirect system of steam heating is by
far the best yet devised, for it not only warms the room, but insures
perfect ventilation as well. In this system, the air for warming the
room is introduced through registers, having first been heated by
passing over coils of pipe or radiators suitably located in the air
ducts. There is a large volume of pure air constantly entering the
room, which must displace and drive out an equal quantity of impure
air. This escapes principally around the doors and windows, so that
not only is the ventilation effected automatically without the use of
special devices, but all disagreeable indraft of cold air is prevented.
One of the cheapest and best methods of ventilation is to have an
opening near the floor, opening directly into the flue, or some other
outlet especially constructed for it, _with hot water or steam pipes
in this opening_. A moderate degree of heat in these pipes will create
a draft, and draw out the bad air. Only a few of these pipes are
necessary, and the amount of hot water or steam required to heat them
is too small to be worthy of consideration.
The use of a small gas-jet, burning continuously, in a pipe or shaft
has been found to be a most admirable method of ventilating inside
rooms, closets and similar places where foul air might collect if not
replaced by fresh. The following table exhibits the result of careful
experiments made by Mr. Thomas Fletcher, of England, with a vertical
flue 6 inches in diameter and 12 feet high:
TABLE.
+-----------+-----------+-----------+--------------+---------------+
| Gas Burnt | Speed of | Total Air |Air Exhausted |Temperature at |
| per Hour. |Current per| Exhausted |per Cubic foot| outlet. Normal|
| | Minute. | per Hour. | of Gas Burnt.| 62° Fahr. |
+-----------+-----------+-----------+--------------+---------------+
|Cubic Feet.| Feet. |Cubic Feet.| Cubic Feet. | |
| 1 | 205 | 2,460 | 2,460 | 82° |
| 2 | 245 | 2,940 | 1,470 | 92° |
| 4 | 325 | 3,900 | 975 | 110° |
| 8 | 415 | 4,980 | 622 | 137° |
+-----------+-----------+-----------+--------------+---------------+
[Illustration: EXHAUST STEAM HEATING.
Fig. 144.]
Taking the experiments as a whole, it will be seen that in a flue 6
inches in diameter, the maximum speed of current which can be obtained
with economy is about 200 feet per minute; and this was realized with a
gas consumption of 1 cubic foot per hour—1 cubic foot of gas removing
2,460 cubic feet of air.
It should, however, not be required of any system of heating to more
than aid in ventilation. It is the architect’s or builder’s performance
to so arrange lower and upper openings to drive out the bad air.
HEATING BY EXHAUST STEAM.
There are two methods of warming by steam heat—one with live steam
direct from the boiler, and the other with exhaust steam. These two are
frequently carried out in combination, and in fact generally so where
exhaust steam is used at all for warming.
In nearly all manufacturing establishments, office buildings, etc., the
exhaust steam produced will very nearly, if not quite supply sufficient
exhaust steam to furnish all the heat required for heating the building
during average weather, although in extremely cold weather, a certain
amount of live steam might be necessary to use in connection with the
exhaust to supply the required amount of heat.
A simple and convenient device operating upon the suction principle
has been found to be most efficient. By this the exhaust steam is
drawn almost instantly through the most extensive piping; preventing
condensation, freezing and hammering, after which it is condensed and
purified, and fed back into the boiler by the means of a reciprocating
pump.
It is claimed that a given quantity of exhaust steam can be circulated
by this vacuum system and uniformly distributed through double the
amount of heating pipes than could be accomplished by the same quantity
of exhaust steam when forced into the heating system by pressure.
Fig. 144 is a well-tried system of heating by exhaust steam in which
“7” represents the steam exhaust pipe, with “6” showing back pressure
valve with weight to adjust amount of back pressure; “4” “4” are steam
supply pipes to radiators; “5” “5” are risers; “9” “9” are condensation
return pipes from the radiators; “8” is the pressure regulating
valve from the boilers. Fig. 144 may also be said to represent the
general method of piping used in steam and hot water heating, which is
difficult of illustration owing to the fact that each locality where it
is used requires a different adaptation.
CARE OF STEAM FITTINGS.
Many steam fittings are lost through carelessness, particularly in
taking down old work, but the great bulk are simply “lost” for lack
of method in caring for them. This task properly falls upon the
engineer, as he usually is intrusted with the selection and ordering
of the necessary work. A great saving in the bill of “findings” can be
effected by proper attention.
The same systematic care exercised over the other fittings, tools,
appliances, oil, fuel, etc., used or consumed in the engine and boiler
room may be urged with equal emphasis.
+------+-------+--------+-------+---------+-------+-------+----------+
| | | | | | | | 1/4 and |
| | | | | | | | 3/8 in. |
+------+-------+--------+-------+---------+-------+-------+----------+
| | | | | | | | 1/2 in. |
+------+-------+--------+-------+---------+-------+-------+----------+
| | | | | | | | 1 in. |
+------+-------+--------+-------+---------+-------+-------+----------+
| | | | | | | |1-1/4 in. |
+------+-------+--------+-------+---------+-------+-------+----------+
| | | | | | | |1-1/2 in. |
+------+-------+--------+-------+---------+-------+-------+----------+
| | | | | | R’s | | 2 in. |
|Elbows| Tees. |Nipples.| Plugs.|Reducers.| and |Unions |couplings.|
| | | | | | L’s. | | |
+------+-------+--------+-------+---------+-------+-------+----------+
Fig. 145.
Fig. 145 shows a case for keeping fittings, which will enable one to
find any particular piece without a moment’s delay. In this admirable
arrangement it will be seen that the heavy fittings are all at
the bottom, the light ones at the top. In the top row of all, the
one-quarter and three-eighth inch fittings are placed, being so small
that a partition may be put into that row of boxes, and then have
plenty of room, and giving twice the capacity to that row of pigeon
holes.
Above this case, which is built of one inch boards, may be put a set of
four cupboards, double doors being fitted to each, and thus making a
door over each compartment in the fitting rack. The shelves run through
these cupboards from end to end, and are not divided by vertical
partitions. The necessary brass fittings are kept on these shelves, and
the doors are secured by good locks. The lightest fittings are placed
on the lower shelves in this cupboard, being in greatest demand.
TOOLS USED IN STEAM FITTING.
[Illustration: Fig. 146.]
Fig. 146 represents one form of a pipe cutter which is made to use by
hand; cutters are also made for use by power, which are capable of
cutting off pipes of immense size. In an engineer’s outfit of steam
fitting tools 2 sets are advisable—one to cut pipe 1/8th inch to 1
inch, and the other to cut 1 to 2-inch pipe. Figs. 147, 148, represent
different forms of pipe tongs—the former called “chain” tongs which
will readily hold three-inch pipe. Fig. 149 represents a steam fitter’s
vise which will “take” say, 2-1/2-inch pipe down to 1/8th. Fig.
150 shows a set of taps and dies for small bolts and nuts which is
ordinarily to be found in a steam fitter’s outfit although used very
generally by machinists and others. Fig. 151 shows a pair of gas-pliers
which are used by steam fitters in gas-pipe jobs. Fig. 152 exhibits the
old-fashioned alligator wrench.
In ice and refrigerating jobs of pipe fitting special tubes are used
to assure a niceness of joints and fitting which is not called for in
steam and water service.
[Illustration: Fig. 147.]
[Illustration: Fig. 148.]
[Illustration: Fig. 149.]
COCKS.
The first means in the earliest times of steam engineering, for opening
and shutting the passages in the pipes of steam engines were cocks
and these were all worked by hand and required close attention. A boy
named Humphry Potter being in charge of one of the cocks of Newcomen’s
pumping-engines, and desiring time for play, it is said, managed to
fasten the lever-handles of the spigots by means of rods and string
to the walking beam of the engine, so that each recurrent motion of
the beam effected the change required. This was the first automatic
valve-motion.
[Illustration: Fig. 150.]
[Illustration: Fig. 151.]
[Illustration: Fig. 152.]
VALVES.
The valve is any device or appliance used to control the flow of a
liquid, vapor or gas, through a pipe, outlet, or inlet in any form of
vessel. In this sense the definition includes air, gas, steam, and
water cocks of any kind.
The bellows was probably the first instrument of which they formed a
part. No other machine equally ancient can be pointed out in which they
were required.
By far the most important improvement on the primitive bellows or bag
was the admission of air by a separate opening—a contrivance that led
to the invention of the valve, one of the most essential elements of
steam, of water, as well as pneumatic machinery.
_Valves and Cocks._—Generally described, a valve is a lid or cover to
an opening, so formed as to open a communication in one direction and
close it in another by lifting, turning, or sliding—among the varieties
may be classed as, the cock, the slide-valve, the poppet valve and the
clack-valve. A common form of this valve is shown in Fig. 139, page
261.
An every day example of a valve, and almost the simplest known, is that
of an ordinary pump where the valve opens upward to admit the water and
closes downward to prevent its return.
A valve has a seat, whether it be a gate or circular valve, and is
generally turned by a circular handle fitted to the spindle.
_Difference between a cock and valve._—The cock is a valve, but a valve
is not a cock; the cock is a conical plug slotted and fitted with a
handle for turning the cone-shaped valve, with its opening in line, or
otherwise, with the opening of the pipe.
_Globe Valve_ is a valve enclosed in a globular chamber, Fig. 135.
This, like many other valves, takes its name from its shape.
Globe valves, whenever possible, should be placed _so that the pressure
comes under the valve_, or at the side, for if the valve should become
loose from the stem (which they often do) if the pressure is on top,
there would be a total stoppage of the steam.
_Relief Valve_ is a valve so arranged that it opens outward when a
dangerous pressure or shock occurs; a valve belonging to the feeding
apparatus of a marine engine, through which the water escapes into the
hot well when it is shut off from the boiler.
_Hinged Valves_ constitute a large class, as for example the
butterfly-valve, clack-valves, and other forms in which the leaf or
plate of the valve is fastened on one side of the valve seat or opening.
_Valve-bracket_ is a bracket fitted with a valve.
_The Valve-chamber_ is where a pump valve or steam valve operates.
_Valve-cock._—A form of cock or faucet which is closed by dropping of a
valve on its seat.
_Valve-coupling_ is a pipe coupling containing a valve.
_Valve-seat_ is the surface upon which a valve rests.
_Back pressure valves_ are ball or clack valves in a pipe which
instantly assume the seat when a back pressure occurs. They are
illustrated in “6,” Fig. 144. Their name signifies their use—to
maintain a constant back pressure in heating systems.
_Ball-valve_—a faucet which is opened or closed by means of a ball
floating in the water. It constitutes an automatic arrangement for
keeping the water at a certain level.
_Bib-cock_—a faucet having a bent-down nozzle.
_Check-valve_—a valve placed between the feed pipe and the boiler to
prevent the return of the water, etc.
_Brine-valve_—a valve which is opened to allow water saturated with
salt to escape. In marine service it is “a blow-off valve.”
_Ball-valve_—a valve occupying a hollow seat. These valves are raised
by the passage of a fluid and descending are closed by gravity.
_Angle-valve_ is one which forms part of an angle, see Fig. 137.
_The double-seat valve_ or double-beat valve presents two outlets
for the water. In the Cornish steam engine this is called the
_equilibrium-valve_, because the pressure on the two is very nearly
equalized.
_Three-way cock_ is one having three positions directing the fluid
in either of three directions. This is illustrated in Fig. 138. The
_three-way valve_ is also illustrated on page 259, Fig. 136.
_Four-way cock_ is one having two separate passages in the plug and
communicating with four pipes.
_Gate-valve_—a valve closed by a gate. This is illustrated in Fig. 140.
_Swing or straight-way valve_—this is shown in Fig. 141, page 261.
_Throttle-valve._—This is the valve used to admit steam to the engine
and so termed to distinguish it from the main stop-valve located near
the boiler—to throttle means to choke—hence the throttling of the steam.
_Rotary valves_ are those in which the disc, or plug, or other device
used to close the passage, is made to revolve for opening or closing,
the common stop cock being an illustration.
_Lifting valves_ are those in which the full cone or stopper is lifted
from the valve seat by pressure from below, the poppet, and safety
valves being examples.
_Pressure regulator valve_—this is sometimes called a reducing valve
and is illustrated in Figs. 142, 143, on page 262. It is designed to
reduce the pressure from a high point in the boiler to a lower one in a
system of piping, etc.
Usually the smaller valves, not exceeding 1-1/4 inch in diameter, are
wholly of gun-metal; the larger are commonly made with cast-iron bodies
and gun-metal fittings. The smallest valves, from 1/4 up to 1/2 inch
inclusive, have the disk solid with the spindle, and have an ordinary
stuffing-box with external gland. Valves of 3/4 inch and upwards have
the disk loose from the spindle; up to 3 inch valves the spindles
are screwed to work inside the casing; above that size the screwed
portion is outside the casing. Above the 3-inch size the nozzles of the
cast-iron bodies are generally flanged instead of tapped.
STEAM FITTINGS.
A few of the principal sorts have been illustrated in this work and
still others will be described in the “Index” at the close of the work.
Fig. 123, page 251, illustrates an _elbow_ with outlet. This is
sometimes spelled with the capital L, and again as an ell.
Fig. 124 shows a long _nipple_.
Fig. 125, page 253, exhibits a _bushing_, used to reduce one size pipe
in a line to another.
Fig. 126 is a _cross tee_. This is frequently spelled with a capital T.
Fig. 127 is a _plug_—used to stop apertures in plates or pipes.
Fig. 128, page 254, illustrates a _lock nut_.
Fig. 129 shows a T, as illustrating the difference between a T and a
cross T, Fig. 126.
Fig. 130 is a _coupling_.
Fig. 131, page 255, represents a _reducing coupling_.
Fig. 132 is an illustration of a pipe _union_.
Fig. 133 is a plain _elbow_ (see also Fig. 123.)
STEAM PIPE AND BOILER COVERINGS.
This subject relates to the _radiation of heat_, which allows a
reference to the laws of heat and tables of radiating power of various
substances, as set forth on pages 212, 215.
The importance of a protection of exposed surfaces from radiation of
heat is now undisputed, and many experiments have determined very
closely the relative value of the various non-conducting substances.
_Table of the_ CONDUCTING POWER _of various substances_.
---------------------------+----------
Substance. |Conducting
| Power.
---------------------------+----------
Blotting Paper | .274
Eiderdown | .314
Cotton or Wool, any density| .323
Hemp, Canvas | .418
Mahogany Dust | .523
Wood Ashes | .531
Straw | .563
Charcoal Powder | .636
Wood, across fibre | .83
Cork | 1.15
Coke, pulverized | 1.29
India Rubber | 1.37
Wood, with fibre | 1.40
Plaster of Paris | 3.86
Baked Clay | 4.83
Glass | 6.6
Stone | 13.68
---------------------------+----------
By the above table may be judged the comparative value of different
coverings; blotting paper with _its confined air_, standing at one end
of the list, stone at the other. It should be noted that _the less the
conducting power the better protection against radiation_.
A non-conducting coating for steam pipes, etc., used for many years
with perfect satisfaction, can be prepared by any steam user. It
consists of a mixture of wood sawdust with common starch, used in a
state of thick paste. If the surfaces to be covered are well cleaned
from all trace of grease, the adherence of the paste is perfect for
either cast or wrought iron; and a thickness of 1 inch will produce
the same effect as that of the most costly non-conductors. For copper
pipes there should be used a priming coat or two of potter’s clay,
mixed thin with water and laid on with a brush. The sawdust is sifted
to remove too large pieces, and mixed with very thin starch. A mixture
of two-thirds of wheat starch with one-third of rye starch is the best
for this purpose. It is the common practice to wind string spirally
around the pipes to be treated to secure adhesion for the first coat,
which is about l/5th of an inch thick. When this sets, a second and
a third coat are successfully applied, and so on until the required
thickness is attained. When it is all dry, two or three coats of coal
tar, applied with a brush, protect it from the weather.
A very efficient covering may be made as follows: 1, wrap the pipe in
asbestos paper—though this may be dispensed with; 2, lay slips of wood
lengthways, from 6 to 12 according to size of pipe—binding them in
position with wire or cord; 3, around the framework thus constructed
wrap roofing paper, fastening it by paste or twine. For flanged pipe,
space may be left for access to the bolts, which space should be filled
with felt. Use tarred paper—or paint the exterior.
While a very efficient non-conductor, hair or wool felt has the
disadvantage of becoming soon charred from the heat of steam at high
pressure, and sometimes taking fire. The following table, prepared by
Chas. E. Emory, Ph. D., shows _the value_ of various substances, taking
wool felt as a _unit_.
TABLE OF RELATIVE VALUE OF NON-CONDUCTORS.
-----------------------+-------
Non-Conductor. | Value.
-----------------------+-------
Wood Felt | 1.000
Mineral Wool No. 2 | .832
Do. with tar | .715
Sawdust | .680
Mineral Wool No. 1 | .676
Charcoal | .632
Pine Wood, across fibre| .553
Loam, dry and open | .550
Slaked Lime | .480
Gas House Carbon | .470
Asbestos | .363
Coal Ashes | .345
Coke in lumps | .277
Air space, undivided | .136
-----------------------+-------
LINEAR EXPANSION OF STEAM PIPES.
Wrought iron is said to expand 1/150,000 of an inch for each degree of
heat communicated to it; to make the calculation take the length of the
pipe in inches, multiply it by the number of degrees between the normal
temperature it is required to attain when heated, and divide this by
150,000. Suppose the pipe is 100 feet long, and its temperature zero,
and it is desired to use it to carry steam at 100 pounds pressure—equal
to a temperature of 338 degrees—multiply 100 feet by 12 to reduce it
to inches, and by 338, the difference in temperature; divide this by
150,000, and the result will be 2.7 inches, which would be the amount
of play that would be required, in this instance, in the expansion
joint.
[Illustration: Figs. 153 and 154.]
Figs. 153 and 154 show a properly designed arrangement of steam
connections for a battery of boilers. To the nozzles, risers are
attached by means of flanges, and from the upper ends of these risers
pipes are led horizontally backwards into the main steam pipe. In this
horizontal pipe, the stop valves, one to each boiler, are placed. These
valves should have flanged ends as shown, so that they may be easily
removed, if repairs become necessary, without disturbing any other
portion of the piping. Unlike the engraving, the valve C should be
arranged in another position: the stem should, of course, be horizontal
or nearly so, in order that the valve may not trap water.
By this arrangement it will be seen that the movements of the boilers
and the piping itself are compensated for by the spring of the pipes.
The height of the risers should never be less than three feet, and when
there are eight or ten boilers in one battery, they should be, if room
permits, six to eight feet high, and the horizontal pipes leading to
main steam pipe should be ten or twelve feet or more.
THE STEAM LOOP.
This is an attachment to a steam boiler, designed to return water of
condensation. It invariably consists of three parts, viz.: the “riser,”
the “horizontal” and the “drop leg,” and usually of pipes varying in
size from three-fourth inch to two inches. Each part has its special
and well-defined duties to perform, and their proportions and immediate
relations decide and make up the capacity and strength of the system.
It is, in fact, nothing but a simple return pipe leading from the
source of condensation to the boiler, and, beyond this mere statement,
it is hardly possible to explain it; it has, like the injector and the
pulsometer pump, been called a paradox.
The range of application of the steam loop practically covers every
requirement for the return of water of condensation. If used in
connection with a steam engine, pump, etc., a separator of any simple
form is connected in the steam pipe as close as possible to the
throttle. From the bottom of the separator the loop is led back to the
boiler, and the circulation maintained by it will dry the steam before
it is admitted to the cylinder.
There is necessary to its operation a slight fall in temperature at
the head of the loop, which is accompanied by a corresponding fall in
pressure. The water accumulating in the lower end of the loop next to
the separator, as soon as it fills the diameter of pipe, is suddenly
drawn or forced to the horizontal by that difference in pressure. It is
immaterial how far the water has to be taken back, or how high it is
to be lifted. There is one system now in daily operation lifting the
condensed water over thirty-nine feet, and another lifting it over
sixty-three feet. The strength of the system is increased by length
and height, the only limit to its operation being the practicability
of erecting the necessary drop leg, the height of which depends on
difference in pressures.
[Illustration: Fig. 155.]
Fig. 155 is an illustration of its application to a radiating coil.
To understand the philosophy of its action, and referring to the
illustration, let us assume that all the valves are open, and full
boiler pressure is freely admitted throughout the steam pipe, coil and
loop. Now, if the pressure were exactly uniform throughout the whole
system, the water in the loop would stand at _a_ on the same level
as the water in the boiler. But, as a matter of fact, the pressure
is not uniform throughout the system, but steadily reduces from the
moment of leaving the dome. This reduction in pressure is due in part
to condensation and in part to friction, and although generally small
is always present in some degree. The pressure may be intentionally
reduced at the valve on the coil, and reduction necessarily results
from condensation within the coil itself. A still further reduction
takes place through the loop, so that the lowest pressure in the whole
system will be found at _a_, the point in the loop furthest from the
boiler, reckoned by the flow of steam.
Now it is known that water of condensation invariably works towards,
and accumulates in, a “dead end.” This is due to the fact that, as
already shown, the pressure is lower at the “dead end” than at any
other point in the system, and, as a consequence, there is a constant
flow, or sweep, of steam towards the point of least pressure, which
flow continues as long as condensation goes on. This sweep of steam
carries along with it all the water formed by condensation or contained
in the steam, at first in the form of a thin film, swept along the
inner surface of the loop, and afterwards, when the accumulation of
water is sufficient, in the form of small slugs or pistons of water,
which completely fill the pipe at intervals, traveling rapidly towards
the dead end. The action of the steam sweep is vastly more powerful
than is usually supposed, and, of course, operates continuously and
infallibly to deposit the water in the dead end as fast as accumulated.
In practice, water will speedily be carried over by the loop and
accumulate in the drop leg until it rises to the level _b_, which would
balance the difference in pressure. As the loop will still continue
to bring over water, it follows that as fast as a slug or piston of
water is deposited by the steam on the top of the column at _b, it
overbalances the equilibrium and an equal amount of water is discharged
from the bottom of the column through the check valve into the boiler_.
The result of the practical operation of many systems of this ingenious
device show advantages as follows:
1. Return of pure water to the boiler and saving the heat contained in
said water.
2. Preserving more uniform temperatures, thus avoiding the dangers due
to expansion and contraction.
3. Prevention of loss from open drains, drips, tanks, etc.
4. Maintaining higher pressure in long lines of piping, in jackets,
driers, etc.
5. Enabling engines to start promptly.
6. Saving steam systems from water, thereby reducing liability to
accident.
BOILER MAKERS’ TOOLS AND MACHINERY.
[Illustration: Fig. 156.]
Fig. 156 represents a pair of jack screws. These are invaluable devices
for use in boiler-shops, and also in establishments where ponderous
machinery has to be shifted or otherwise handled.
But few machine tools are used in making steam boilers, and they are
generally as follows:
1st.—_The Rolls_, operated either by hand levers or power; used for
bending the iron or steel plates into circular form.
2d.—A wide _power planer_ for trimming the edges of the sheet perfectly
straight and true.
3d.—_Heavy Shears_ for trimming and cutting the plates.
4th.—A _Power Punch_ for making the rivet holes.
5th.—A _Disc_ for making the large holes in the tube sheets to receive
the ends of the tubes.
6th.—_Rivet heating furnaces_ and frequently _steam riveting machines_.
The hand tools needed by boiler makers are equally few, consisting of
_riveting hammers_ and hammers for striking the chisels, _tongs_ to
handle hot rivets, _chipping chisels_ used in trimming the edges of
plates, _cape chisels_ for cutting off iron or making holes in the
sheets, _expanders_ to set the tubes, and also _drift pins_ to bring
the punched sheet exactly in line.
Fig. 157 exhibits an improved pattern of the well-known tool—dudgeon
expander.
[Illustration: Fig. 157.]
STEAM.
_Steam_ is water in a gaseous state; the gas or vapor of water; it
liquifies under a pressure of 14.7 and temperature of 212° F.
_Steam_ is a joint production of the intermingling of water and heat.
Water is composed of two gases which have neither color nor taste, and
steam is made up of the same two gases with the addition only of that
mysterious property called heat by which the water becomes greatly
expanded and is rendered invisible. The French have a term for steam
which seems appropriate when they call it water-dust.
This is what takes place in the formation of steam in a vessel
containing water in free communication with the atmosphere. At first,
a vapor is seen to rise that seems to come from the surface of the
liquid, getting more and more dense as the water becomes hotter. Then
a tremor of the surface is produced, accompanied by a peculiar noise
which has been called _the singing_ of the liquid; and, finally,
bubbles, similar to air bubbles, form in that part of the vessel which
is nearest to the fire, then rise to the surface where they burst,
giving forth fresh vapor.
The curious fact must be here noted that if water be introduced
into a space entirely void of air, like a vacuum, it vaporizes
instantaneously, no matter how hot or cold, so that of an apparent and
fluid body there only remains an invisible gas like air.
That steam is _dry_ at high pressure is proved by an experiment which
is very interesting. If a common match head is held in the invisible
portion of the steam jet close to the nozzle, it at once lights, and
the fact seems convincing as to complete dryness, as the faintest
moisture would prevent ignition even at the highest temperature. This
experiment proves dryness of the steam at the point of contact, but if
throttling exists behind the jet, the steam supplied by the boiler may
be in itself wet and dried by wire drawing.
_Dead steam_ is the same as exhaust steam.
_Live steam_ is steam which has done no work.
_Dry steam_ is saturated steam without any admixture of mechanically
suspended water.
_High-pressure steam_ is commonly understood to be steam used in
high-pressure engines.
_Low-pressure steam_ is that used at low pressure in condensing
engines, heating apparatus, etc., at 15 lbs. to the inch or under.
_Saturated steam_ is that in contact with water at the same
temperature; saturated steam is always at its condensing point, which
is always the boiling point of the water, with which it is in contact;
in this it differs from superheated steam.
_Superheated steam_, also called steam-gas, is steam dried with heat
applied after it has left the boiler.
_Total heat of steam_ is the same as steam heat.
_Wet steam_, steam holding water mechanically suspended, the water
being in the form of spray.
Specific gravity of steam is .625 as compared to air under the same
pressure.
The properties which make it so valuable to us are:
1. The ease with which we can condense it.
2. Its great expansive power.
3. The small space in which it shrinks when it is condensed either in a
vacuum chamber or the air.
A cubic inch of water turned into steam at the pressure of the
atmosphere will expand into 1,669 cubic inches.
WATER HAMMER.
The fact that steam piping methods have not kept pace with the demands
of higher pressures and modern practice is evidenced by the increasing
number of accidents from the failure of pipes and fittings.
There has not been, for the rapid increase of pressure used, a
proportionate increase in strength of flanges, number and size of
bolts used, and more generous provision for expansion and contraction.
Valves and fittings also require greater attention in their design,
construction and manipulation.
It is well known that the presence of condensed water in pipes is a
source of danger, but little is known of what exactly goes on in the
pipe. We have the incompressible liquid, the expansive gas, and the
tube with a “dead head” or dead end as it is called, or where the end
of the pipe is closed. Seeing that the tube or pipe is capable of
withstanding all the pressure that the steam can give, it is difficult
to account for the tremendous repelling force, which is, undoubtedly,
brought into operation in explosions or ruptures of steam pipes
carrying what are now comparatively low pressures.
The cause of the bursting is undoubtedly _water hammer or water ram_,
which accompanies large, long steam pipes, filled with condensed water.
If steam be blown into a large inclined pipe full of water, it will
rise by difference of gravity to the top of the pipe, forming a bubble;
when condensation takes place, the water below the bubble will rush up
to fill the vacuum, _giving a blow directly against the side of the
pipe_. As the water still further recedes the bubble will get larger,
and move farther and farther up the pipe, the blow each time increasing
in intensity, for the reason that the steam has passed a larger mass
of water, which is forced forward by the incoming steam to fill the
vacuum. The maximum effect generally takes place at a “dead end.”
In fact, under certain conditions, a more forcible blow is struck
when the end of the pipe is open, as, for instance, when a pipe
crowned upward is filled with water, one end being open and the steam
introduced at the other. A bubble will in due time be formed at the top
of the crown, when the water will be forced in by atmospheric pressure
from one end and by steam pressure from the other, and the meeting of
the two columns frequently ruptures the pipe.
The remedy for this is simple, the pipes must be properly located so as
to drain themselves or be drained by rightly located drip cocks. The
drip should be the other side of the throttle valve, and if steam is
left on over night this valve should be left open enough to drain out
all the water.
HAZARDS OF THE BOILER ROOM.
Where there is great power, there is great danger.
When the pressure is increased, the danger is increased.
When the pressure is increased, diligence, care and scrutiny should be
increased.
During the twelve years between 1879 and 1891 there were recorded 2,159
boiler explosions; these resulted in the death of 3,123 persons, and in
more or less serious injury to 4,352 others. Besides these there were
innumerable other accidents during the same period, caused by other
means, which emphasizes the gravity of this cautionary “chapter of
accidents.”
Every boiler constructed of riveted plate and carrying a high head of
steam, holds in constant abeyance, through the strength of a disruptive
shell, a force, more destructive in its escaping violence than burning
gunpowder. To the casual observer there is no evidence of this; and it
is only when a rupture takes place of such a character as to liberate
_on the instant the entire contents of the boiler_ that we get a real
demonstration of the fact. Unfortunately a steam boiler never grows
stronger, but deteriorates with every day’s age and labor, subjected,
as it is, to all sorts of weakening influences; and fractures often
occur, which, if not at once repaired, would speedily reduce the
strength of the boiler to the point of explosion.
In the case of a boiler we have, first, a vessel of certain strength,
to resist strains; and second, expansive steam and water contained
therein. It must be plain that if the strength of the vessel is
superior to the internal pressure there can be no explosion, and also,
on the contrary, if we allow the pressure to go above the strength of
the vessel, that there must be a rupturing and an explosion, but it
will be in the weakest place of that vessel.
Experiments by the most eminent men have failed to discover any
mysterious gas formed by boiling water, or by any mixture of air
and water. Boilers have been built for the express purpose of trying
to explode them under various conditions of high and low water,
and nothing in regard to the sudden generation of any gas has been
discovered. Again, disastrous explosions that have occurred have been
of vessels that contained no water, and were not in contact with fire,
flame or heated air, but were supplied by steam some distance away.
The destructive efforts of the vaporization attendant upon explosions
seem to be due to the subsequent expansion of the steam so formed,
rather than to the intensity of its pressure; low or high steam _alone_
has very little to do with boiler explosions; nor high or low water
necessarily.
The one great cause of boiler explosion is the inability of the boiler
to withstand the pressure to which it is subjected at the time, and
this may be brought about by any one of the following causes, viz.:
1. Bad design, in which the boiler may not be properly strengthened
by stays and braces; deficient water space, preventing the proper
circulation of the water.
2. Bad workmanship, caused by the punching and riveting being done by
unskilled workmen.
3. Bad material, blisters, lamination, and the adhesion of sand or
cinders in the rolling of the plate.
4. By excessive pressure, caused by the recklessness of the engineer,
or by defective steam-gauges or inoperative safety-valves.
5. Overheating of the plates, caused by shortness of water. When water
is poured on red-hot surfaces it does not touch the surface, but
remains in the spheroidal state at a little distance from it, being
apparently surrounded by an atmosphere of steam. It assumes this state
above 340°; when the temperature falls to about 288° it touches the
surface and commences boiling.
6. By accumulation of scale, mud, or other deposit, which prevents the
water gaining access to the iron. This causes the seams to leak, the
crown-sheet to bulge or come down.
One is unable to find any proof that boilers do generally explode at
about starting time, nor is that statement, to the best of information,
founded on any basis of fact, but was first affirmed by parties who had
designed a boiler especially arranged to avoid that imaginary danger.
No one supposes that inspection will absolutely prevent all explosions;
but rigid inspection will discover defects that might end in explosion.
Low water is dangerous from the fact that it leaves parts of the boiler
to be overheated and the strength of iron rapidly decreases in such a
case. In fact, an explosion caused by low water might be expected to be
less disastrous than if the water was higher, other conditions being
equal, from the fact of there being less water at a high temperature
ready to flash into steam at the moment of liberation.
Testing new boilers _under steam pressure_ is both dangerous and
unwise—the hot water expansion test is just as efficient, less costly
and safe in every respect—hence, there is no occasion for a steam test.
A manufacturer was testing a boiler in the way mentioned when a rivet
in a brace blew out and the contents of the boiler rushed out, striking
a man in the face, and parboiling him from head to foot. Another who
was inspecting the boiler, was struck on the head and enveloped in
steam and water; another was also scalded from the shoulders down;
another was injured about the arms; a fifth man was scalded and
severely injured about the back. The apartment was so filled with steam
that the victims could not be rescued until all the damage mentioned
had been done to them.
Danger from exploding steam pipes is greater than supposed.
An inspector in a pipe works was testing a tube by means of a
double-action hydraulic pump; the pipe suddenly burst with the
pressure of 5,000 pounds to the square inch, and the water striking the
unfortunate man on his face, he was killed on the spot.
There is a tendency on the part of engineers to trust too implicitly in
their steam gauges. These are usually the only resort for determining
the steam pressure under which the boiler may be working. But the best
gauges are liable to err, and after long use to require a readjustment.
It is fortunate, however, that the error is usually upon the safe side
of indicating more than the actual pressure.
Any boiler that has been standing idle for a few weeks or months is a
dangerous thing to enter, and no one should attempt it until it has
been thoroughly ventilated by taking off all the man hole and hand-hole
plates and throwing water into it. This is due to the presence of a
gas which is generated from the refuse and mud, or scale, which, to a
greater or less degree, remains in all boilers. Contact with fire is
certain to result in an explosion. Not long since a locomotive was in
a roundhouse, where it had been waiting some weeks for repairs. Some
of the tubes were split and a man was pulling them out. He had only
removed one or two when, putting in his lamp to see what remained,
there was a fearful explosion which shook the shop. There are many
other places which are unsafe to enter when they have been long closed,
such as wells, pits of any kind, and tanks. Precisely what the nature
of the gas is no one seems to know, but it is assuredly settled that a
man who goes into it with a light seldom comes out unharmed.
The gas most likely to fill idle boilers in cities is sewer gas, that
gets in through the blow-off pipe, which is left open and generally
connects with the sewer; hence, the connection with the sewer by the
blow-off pipes should receive attention.
Boilers are sometimes unexpectedly emptied of their contents by the
operation of the principle of the syphon; a boiler is so piped that
a column of water may be so formed as to draw out of the boiler its
entire contents. Danger ensues if this is done while the boiler is
being fired.
FUEL OIL.
[Illustration: Oil Valve]
The long experimental use of petroleum or natural oil as a combustible
has developed but one serious objection to its wide spread and popular
adoption; that objection arises from its liability to ignite and cause
destruction by fire; but
THE HAZARDS OF FUEL OIL may be remedied by the observance of the
following rules adopted by a certain fire underwriters’ association:
“Vault to be located so that the oil it contains can burn without
endangering property and have a capacity sufficient to hold twice the
entire quantity of oil the tanks within can contain.
Location of vault to be left to the approval of the Superintendent of
Surveys. Distance from any property to be regulated by size of tank.
Vaults to be underground, built of brick, sides and ends to be at
least 16 inches thick and to be made water tight with hydraulic
cement; bottom to be water tight, concrete, dished toward centre, and
inclined to one end so as to drain all overflow or seepage to that
end, said incline to be to the end opposite to that from which the
tank is to be tapped; top to be supported with heavy iron I-beams,
with arches of solid brick sprung from one beam to its neighbors, and
to have at least twelve inches of dirt over the masonry.
Vault to be accessible by one or more large man-holes, which, when
not in use, are to be kept locked by a large padlock of three or more
tumblers, key to be held by some responsible party.
A trough must run from one end of the vault to the other, directly
under each tank, and in the same direction as the tank or tanks.
Tank to be of boiler iron or steel, at least 3/16 inch in thickness,
to be cold riveted, rivets to be not less than 3/8 inch in
diameter and not over 1 inch apart between centres; the entire outer
surface of tank to have two good coats of coal tar or mineral paint
before the tank is placed in position.
No tank shall be over 8 feet in diameter by 25 in length, nor shall
any vault have over two tanks.
When tank is set, the bottom of the tank must be 3 inches above the
concrete floor of the vault, and must be in saddles of masonry not
less than twelve inches in thickness, built from the concrete floor
of the vault, said saddles not to be more than 3 feet apart between
centres, and laid in hydraulic cement, with an opening through centre
for drainage.
Tank must incline 1 inch per 10 feet in length toward the end from
which it is to be tapped, said incline of the tank to be opposite to
the incline at the bottom of the vault.
The filling pipe, man-hole, telltale or indicator, pump supply
connection, steam connection, overflow pipe and ventilating pipes,
where they connect with tank, must be made petroleum tight by the use
of litharge and glycerine cement.
Flanges to make tank 3/4 inch in thickness to be riveted on the
inside so as to furnish a satisfactory joint where connections are
made, must be used.
Filling pipe connection must have gas-tight valve between the tank
and hose coupling, which must be kept closed and locked unless the
tank is being filled. Each tank must have ventilating pipes at least
1-1/2 inches in diameter, one of which must connect with one end
of the top of the tank and must be in the form of an inverted J, a
union to be placed in pipe just below the bend, within which shall
be placed a diaphragm of fine wire gauze; the other ventilating pipe
must be at the other end of the top of the tank and must be conducted
to the inside of the smoke stack or into the open air at least 10
feet above the surface, so that all the gases that form in the tank
will be constantly changed.
Tank must have indicator to show height of oil in tank at all times,
said indicator to be so arranged as to allow no escapement of gases
from tank. All pipes leading from the tank to the pump or place of
burning, must incline toward the tank, and have a fall of at least 2
feet from bottom of stand pipe to top of storage tank, and must be so
constructed that the feed pipe from stand pipe to burners shall be
entirely above burners, so that no pockets of oil can be formed in
any one of the pipes between the main tank, stand pipe, oil pump or
place of burning.
The vault shall be air tight as near as possible, and must have
two ventilating pipes of iron of 4 inches diameter, both inlet and
outlet pipes to reach within 6 inches of the bottom of the vault, the
outlet ventilating pipe to rise above surface 8 feet, and the inlet
ventilating pipe to rise above surface 6 feet.
Syphon to be arranged so as carry out any seepage or leakage into the
vault, and discharge same upon the ground, where its burning would
not endanger surrounding property.”
_The following are a part of the rules adopted by the German Government
to prevent accidents in mills and factories: they are equally
applicable in all places where steam power is used_:
“All work on transmissions, especially the cleaning and lubricating
of shafts, bearings and pulleys, as well as the binding, lacing,
shipping and unshipping of belts, must be performed only by men
especially instructed in or charged with such labors. Females and
boys are not permitted to do this work.
The lacing, binding or packing of belts, if they lie upon either
shafting or pulleys during the operation, must be strictly
prohibited. During the lacing and connecting of belts, strict
attention is to be paid to their removal from revolving parts, either
by hanging them upon a hook fastened to the ceiling, or in any
other practical manner; the same applies to smaller belts which are
occasionally unshipped and run idle.
While the shafts are in motion they are to be lubricated, or the
lubricating devices examined only when observing the following
rules: (1) The person performing this labor must either do it while
standing upon the floor, or by the use of (2) firmly located
stands on steps, especially constructed for the purpose so as to
afford a good and substantial footing for the workman; (3) firmly
constructed sliding ladders, running on bars; (4) sufficiently high
and strong ladders, especially constructed for this purpose, which
by appropriate safeguards (hooks above or iron points below) afford
security against slipping.
All shaft bearings are to be provided with automatic lubricating
apparatus.
Only after the engineer has given the well-understood signal, plainly
audible in the workrooms, is the engine to be started.
If any work other than lubricating and cleaning of the shafting is to
be performed while the engine is standing idle, the engineer is to
be notified of it, and in what room or place such work is going on,
and he must then allow the engine to remain idle until he has been
informed by proper parties that the work is finished.
Plainly visible and easy accessible alarm apparatus shall be located
at proper places in the workrooms, to be used in case of accident to
signal to the engineer to stop the engine at once.
_All projecting wedges, keys, set-screws, nuts, grooves or other
parts of machinery, having sharp edges, shall be substantially
covered._
All belts or ropes which pass from the shafting of one story to that
of another shall be guarded by fencing or casing of wood, sheet-iron
or wire netting four feet, 6 inches high.
The belts passing from shafting in the story underneath and actuating
machinery in the room overhead, thereby passing through the ceiling
must be enclosed with proper casing or netting corresponding in
height from the floor to the construction of the machine. When the
construction of the machine does not admit of the introduction of
casing, then, at least, the opening in the floor through which the
belt or rope passes should be inclosed with a low casing at least
four inches high.
Fixed shafts, as well as ordinary shafts, pulleys and fly-wheels,
running at a little height above the floor, and being within the
locality where work is performed, shall be securely covered.”
The most simple and efficient of all substances for fire extinguishment
is sulphur. This, by heat, absorbs oxygen and forms sulphurous acid,
the fumes of which are much heavier than the air. The quantity required
would be small. Besides sulphur, which gives every satisfaction, both
in its effects and from its low cost, we find a similar property in
another active and cheap substance, ammonia. An automatic sulphur
extinguishing apparatus can be made of various forms.
If night repairs, Sunday, or any other work which requires the use
of artificial light (especially portable lights of any kind) becomes
necessary, more than one man should be employed, one of whom should be
capable of starting the engine or pump instantly in case of fire.
In guarding against explosion it is conceded that the main reliance is
to have the boiler made strong enough to stand both the regular load
or any unexpected strain caused by the stoppage of the engine; it is
also the tendency of the times to proceed towards higher and higher
figures in steam pressure, until now it is not unfrequent to see 150
lbs. to the square inch indicated by the gauge; the larger the boiler,
also, the more economically it can be run and this, as in the two cases
before cited, requires extra precautions in building the boiler with
great regard to strength in every part.
The following rules posted in a certain factory are most excellent for
their directness:
“Wear close-fitting clothes; have a blouse or jacket to button close
around the waist and body; have sleeves to fit arms closely as far
up as the elbow; never wear a coat around machinery; never approach
a pair of gears or pulleys from the driving side; never attempt to
save time by potting, or trying to pot on any fast-moving belts
without slacking up or stopping entirely to do it. Never allow an
inexperienced person to go through the mills without an attendant;
never allow a woman to go through a mill, no matter how many
attendants, while in motion; never attempt to go through the mill in
the dark, you may forget the exact location of some dangerous object
and seek to avoid it, but it is still there, noiselessly waiting a
chance to wreck you; never allow any dangerous place to go unguarded;
keep your eye open while oiling; never relax your vigilance for an
instant, it may cost you your life. If you feel a gentle tug on your
clothes, grab, and grab quick, anything you can cling to, and don’t
let go till after the clothes do.”
WATER CIRCULATION.
Water consists of an innumerable quantity of extremely minute particles
called molecules. These particles have the property of being able to
glide over, under, and to and from each other almost without resistance
or friction. When water is heated in a boiler the action that takes
place is this: As the heat is applied, the particles nearest the heated
surfaces become expanded or swollen, and are so rendered lighter (bulk
for bulk) than the colder particles, they are therefore compelled to
rise to the highest point in the boiler.
[Illustration: Fig. 158.]
This upward action is vividly shown by the illustration on page 242,
and by Fig. 158, where the warmer particles are ascending and the
cooler ones are descending by a process which is endless so long as
heat is applied to the lower part of the containing vessel.
The cause of circulation is the result of an immutable law of nature
(the law of gravitation), and is so simple that with moderate care
in its manipulation failures in arranging steam heating apparatus are
next to impossible. A very slight experience suffices to show that a
pipe taken from the top of a boiler and given a direct or gradual rise
to the point furthest from the boiler, and then returned and connected
into it at the bottom will, upon the application of heat, cause the
water to circulate. It is not necessary that the water should boil or
even approach boiling point, to cause circulation, as in a properly
constructed apparatus the circulation commences soon after the heat is
applied and immediately the temperature is raised in the boiler. It is
a very common error to suppose that the circulation commences in the
flow or up pipe, whereas it is just the reverse. The circulation is
caused by the water in the return pipe and can be described as a stream
of heated particles flowing up one pipe from the boiler and a stream of
cooler particles flowing down another pipe into the boiler; or it might
be described as a means of automatically transporting heated water from
the lower to the upper parts of a building, and providing a down flow
of cold water to the boiler to be heated in turn.
Those having in charge the erection of hot-water systems for heating
buildings, will do well to remember that the circulation they expect
depends entirely upon the expansion of particles when heated, and that
they must avoid as much as possible friction, exposure of flow pipes to
very low temperature, and frequent or numerous short bends.
When properly arranged the action of “the steam loop” is a very good
illustration of the circulation of hot water and steam, the flow is
continuous, rapid and positive.
NOTE.—When the steam loop is properly connected, the stop valve at the
boiler should always be left open and full pressure maintained in the
steam pipe over night or over Sunday. The loop will keep up a powerful
circulation, returning all water to the boiler as fast as condensed.
On starting up in the morning, it is only necessary to open the
waste cocks and blow out what little water may have condensed in the
cylinders themselves. The throttle may then be opened and the engine
started with the steam as dry as if it had been running continuously.
CHIMNEYS AND DRAUGHT.
Draught, in chimneys, is caused by the difference between the weight of
the air outside and that inside the chimney. This difference in weight
is produced by difference in heat.
Now, heated air has a strong tendency to rise above cool air and a very
slight difference will cause an upward flow of the heated particles,
and the hotter the air, the brisker the flow.
As these particles ascend it leaves a space which the cooler air
eagerly hastens to fill; in the boiler furnace, the hot air pushing its
way up the chimney, is replaced through the grate bars with cool, fresh
air.
It is the mingling of this fresh air with the combustibles that
produces heat, and the power of the draught is absolutely necessary to
the reliable operation of the furnace.
An excess of draught can be corrected by the use of a damper or even by
the closing of the ash pit doors, but no more unhappy position for an
engineer can be imagined than a deficiency of draught.
This lack is produced by, 1st, too little area in the chimney flue; 2d,
by too low a chimney; 3d, by obstructions to the flow of the gases;
4th, by the overtopping of the chimney by adjacent buildings, hills or
tree tops. There are other causes of failure which practice develops;
hence, the draught of a new chimney is very often an uncertain thing
until every-day trial demonstrates its action.
The draught of steam boilers and other furnaces should be regulated
below the grate and not in the chimney. The ash pit door should be
capable of being closed air tight, and the damper in the chimney should
be kept wide open at all times unless it is absolutely necessary to
have the area of the chimney reduced in order to prevent the gases from
escaping too fast to make steam.
When two flues enter a larger one at right angles to it, opposite
each other, as is frequently the case where there is a large number
of boilers in a battery, and the chimney is placed near the center of
the battery, the main flue should always have a division plate in its
center between the two entering flues to give direction to the incoming
currents of gases, and prevent their “butting,” as it may be termed.
The same thing should always be done where two horizontal flues enter a
chimney at the same height at opposite sides.
In stationary boilers the chimney area should be one-fifth greater than
the combined area of all the tubes or flues.
For marine boilers the rule is to allow fourteen square inches of
chimney area for each nominal horse power.
The draught of a chimney is usually measured in inches of water. The
arrangement most commonly made use of for this purpose consists of a
U-shaped glass tube connected by rubber tubing, iron pipe, or other
arrangement, with some part of the chimney in such a way that the
draught will produce a difference of level of water in the two legs of
the bent glass tube.
The “Locomotive” suggests that _the unit for chimney construction_
should be a flue 81 feet high above the level of the grates, having
an area equal to the collective area of the tubes of all the boilers
leading to it, the boilers being of the ordinary horizontal return
tubular type, having about 1 square foot of heating surface to 45
square feet of heating surface.
Note the above conditions, and, in case of changing the above
proportions, it should be observed that the draught power of chimneys
is proportional to the square root of the height, so we may reduce
its area below the collective area of the boiler tubes _in the same
proportion that the square root of its height exceeds the square root
of 81_.
For example, suppose we have to design a chimney for ten boilers, 66
in. in diameter, each having 72 tubes, 3-1/2 in. in diameter, what
would be its proportion?
The collective area of the 720 3-1/2-in. tubes would be 6,017 square
inches, and if the chimney is to be but 81 feet high, it should have
this area, which would require a flue 6 ft. 5-1/2 in. square.
But, suppose, for some reason, it is decided to have a chimney 150 feet
in height, instead of 81 feet. The square root of 150 is 12-1/4; the
square root of 81 is 9; and we reduce the area of the chimney by the
following proportion: 12.25:9 = 6,017:4,420 square inches, which would
be the proper area, and would call for a chimney 5 ft. 6 in. square,
and similarly if any other height were decided upon.
PLUMBING.
[Illustration: Pipe Trap]
[Illustration: P Trap]
The art of working in lead is older than the pyramids. For thousands
of years hydraulics and plumbing as an occupation engaged the
principal attention of engineers. King David used lead pipe, so did
Archimedes; the terraces and gardens of Babylon were supplied with
water through leaden pipes. Steam fitting, with galvanized pipe and
an elaborate system of connections and devices is a new department of
mechanism—almost of the present generation—and at first sight would
seem able soon to supercede lead piping of all kinds, but it is safe to
say that nothing can ever take the place of lead, for this admirable
metal can be made to answer where no other material can be worked; for
instance, lead pipe can be made to conform to any angle or obstruction
where no other system of piping will. Hence, plumbing as a useful and
ornamental art will never go out of date, and engineers of every branch
will do well to study its principles and methods so as to meet the
ever-recurring and perplexing questions connected with sewerage, water
supply, etc.
[Illustration: S Trap]
Every engineer should at least know how 1, _to join lead pipe_—to make
a “wipe joint,”—as in a hundred emergencies this knowledge will be of
worth. 2, how to make a temporary stopping of leaks; 3, how to bend
pipe with sand or springs; 4, how to “back air pipes” from sinks; 5,
how to use force pumps; 6, how to arrange the circulating pipes in
hot-water boilers; 7, how to make solder; 8, how to repair valves,
etc., etc.
PIPING AND DRAINAGE.
The three illustrations on page 298 are designed to represent traps set
in lead pipe and show vividly the difference between this material and
iron piping.
[Illustration: Fig. 159.]
Lead is one of the elementary substances of which the world is formed;
it ranks with gold, silver, tin, etc., in being an unmixed metal.
It melts at about 617° Fahrenheit, and is, bulk for bulk, 11-4/10
heavier than water (gold being 17-5/10 heavier and wrought iron 7-7/10
heavier). The tenacity of lead is extremely low, a wire 1/18th of an
inch breaks with a weight of 28 lbs.; in comparison, its tenacity is
only one-twentieth that of iron; it is so soft that it may be scratched
with the thumb nail. If a very strong heat is applied lead boils and
evaporates; it transmits heat very slowly; of seven common metals it is
the worst conductor, therefore it is good for hot water pipes. Mixed
with a sufficient quantity of quicksilver it remains liquid.
An advantage to be found in the use of lead is its durability and
comparative freedom from repairs. In London, soil and drain water pipes
which have been fixed 300 to 500 years are as good now as the day they
were first made—while iron pipe cannot be expected to last over 10 or
20 years or 30 at the utmost.
Fig. 159 represents the general system of house piping and drainage
applicable also to shops, public buildings, etc. A exhibits the drain
or sewer. A-C represents the sewer connection, so called with a running
trap, B. “C” at the end of the lower pipe exhibits a soil pipe elbow,
with hand hole for cleaning out closed by a screw plug. This drain
should have a regular fall or inclination and this elbow provides for
that. C-D shows the rain water leader (conductor).
E and F is a soil pipe 3, 4, 5, or 6 inches in diameter. Note, pipes
draining water closets are called “soil pipes”; those draining other
fixtures “waste pipes.” N and O represent water-closet flanges; F and
H are roof connections; L exhibits double and single =Y= branches to
receive waste-pipes from baths, bowls, or sinks. The plumber makes this
connection, always trapping the lead waste-pipe and then soldering it
to a _brass_ nipple.
LEAD PIPE JOINTS.
[Illustration: Fig. 160.]
It has been remarked that after learning how to make “a wipe joint,”
everything is easy relating to the plumber’s trade; hence, the
importance of the following directions.
To learn the art, previous practice with short pieces of pipe is
recommended. This trial piece can be clamped as shown in Fig. 160 and
used over and over until practice has been had.
There are many names for the process of lead joint-making, such as the
flow-joint, the ribbon joint, the blown joint, the astragal joint,
etc., to express the different positions and uses for which they are
needed, but in the main they are made as follows:
1. The lead pipe to be joined is sawn square off with the proper
toothed saw—attention being paid to making the end absolutely true,
across the pipe.
2. One end of the pipe to be joined is first opened by driving in a
wooden wedge, shaped like a plumb-bob, called the “turn pin.” Care
should be exercised at this time not to split the end, 1/4 inch opening
is usually enough, which leaves the pipe as shown at D, Fig. 161. Now,
clean the internal part of the joint all around the part required for
soldering—this cleaning can be done with the plumber’s shave hook or
with a pocket knife. To complete this preparation “touch” the part with
grease from a tallow candle.
3. Next is the preparation of the male part of the joint. This must be
rasp-filed down to fit the enlarged opening. It is important to have a
good fit throughout; hence, inside the enlarged opening must be also
rasp-filed and the two surfaces to come nicely together before the
solder is applied.
4. At this stage a paste called “plumber’s soil” must be applied
outside 3 inches from the end of each piece of pipe; this is shown
by the line E F in Fig. 161, also at A B, Fig. 160; the line of the
soiling should be very even and true in order to assure a workmanlike
job and the soiling put on as before stated, _3 to 5 inches beyond the
solder line on each side_.
As the melting point of lead is 612 degrees or thereabouts, it is
necessary to have solder melt at a lower temperature, and that made
under the rule given will melt at 440 to 475 degrees.
No tool to a plumber is more important than the cloth used in joint
making. To make it, take a piece of new mole skin or fustian, of
moderate thickness, 12 inches long by 9 inches wide, fold it up one
side 4 inches; then 4 inches again, and again 4 inches; then fold it
in the middle, which will make your cloth 4 × 4-1/2 inches, and of 6
thickness. After this is done, sew up the ragged ends to keep it from
opening. Then pour a little hot tallow on one side and the cloth is
ready for use. In Fig. 160-a is shown, H, a hand holding the cloth C in
the process of “wiping the joint,” which will now be described.
First place a small piece of paper under the joint to catch the surplus
solder D and begin soldering as follows: Take the felt F in the right
hand and with it hold the ladle three parts full of solder. To see that
it is not too hot hold your hand within 2 inches or so of the solder;
if it quickly burns your hand it is too hot; if you can only just hold
your hand this distance, use it; but if you cannot feel the heat, the
solder is too cold.
When you begin to pour your solder upon the joint do it very lightly
and not too much at a time in one place, but keep the ladle moving
backward and forward, pouring from E to J, first on one side of the
joint to the other and from end to end.
Pour also an inch or two up the soiling, as shown at E to make the pipe
of proper temperature, _i.e._, to the same heat as the solder. The
further, in reason, the heat is run or taken along the pipe, the better
the chance of making the joint.
[Illustration: Fig. 160-a.]
Keep pouring and with the left hand hold the cloth C to catch the
solder and also cause the same to tin the lower side of the pipe and to
keep the solder from dropping down. This cloth, so important in joint
making is elsewhere described. By the process of steady pouring the
solder now becomes nice and soft and begins to feel shaped, firm and
bulky.
When in this shape and in a semi-fluid condition quickly put the ladle
down, and instantly with the left hand shape one side of the joint
always beginning at the outsides, or at that part next the soiling;
then take the cloth in the right hand and do the other side, _finishing
on the top_; a light run of the cloth all round the joint will, if the
solder has not set and you have been quick with your work, give the
appearance of a turned joint. After a little practice the joint may be
made without changing the cloth from one hand to the other.
_The secret of joint making is getting the lead to the heat of the
solder and in roughly shaping the solder, while in the semi-fluid
state._
Good mechanical fitting is the result of two things—good judgment and a
delicate sense of touch.
REPAIRING PIPES WITH PUTTY JOINTS.
[Illustration: Fig. 161.]
First get the pipe _thoroughly dried_, and with some quick drying
gold size paint the part to be repaired; then get some white lead and
stiffen it with some powdered red lead, so as to make it a hardish
putty, place a thin layer of this, say 3/8th inch to 1/2 inch in
thickness, over the bursted part of the pipe, and with some good strong
calico, painted with the gold size, neatly wrap the red lead to the
pipe, using 3 or 4 thicknesses of the painted calico; then with some
twine begin at one end, laying the twine in several layers in rotation
until it has, like the calico, several thicknesses.
If properly done this will be strong enough to withstand any ordinary
pressure on the pipes and if more is required the putty can be made
from dry red lead and gold size. In making all white and red lead
joints, first, see that the parts are thoroughly dry; second, see that
the parts are not dirty with rust, &c.; next, well paint the parts with
good, stiff paint before putting the putty on to form the joint.
BENDING LEAD PIPE.
If any ordinary piece of light lead pipe 1-1/2 inches in diameter is
taken and pulled or bent sharply around it will crimple or crinkle at
the throat; the larger and thinner the pipe the more it will become
distorted.
There are many methods of making these bends in lead pipe, some with
dummies, others with bolts, balls, etc., others cut the bends at the
back, at the throat, or the two sides of the bend.
For small pipes, such as 1/2 to 1 inch and extra heavy, they may be
pulled round without trouble or danger, but for a little larger size
SAND BENDING is largely practiced as follows:
Take the length of pipe, say 5 feet, fill and well ram it with sand 2
feet up, then have ready a metal pot of very hot sand to fill the pipe
1 foot up, next fill the pipe up with more cold sand, ramming it as
firmly as possible, stop the end and pull round the pipe, at the same
time hammering quickly working the lead from the throat towards the
back, which can be done if properly worked. N. B.—Care must be used not
to reduce or enlarge the size of the bore at the bend.
BENDING WITH WATER.—It is a well-known fact that for such work, water
is incompressible, but may be turned or twisted about for any shape
provided it is enclosed in a solid case. To make the bend—the end of
the pipe is stopped and a stop cock soldered into the other end; take
the pipe at the end and pull it around, being careful that the water
does not cool and shrink, and hammering quickly to take out the crinkle.
BENDING WITH BALLS.—This method is practiced with small pipe and also
to take “dints” out in case of sand and water bending when a ball is
sent through. Method: suppose the pipe to be two inches, then a ball is
required 1/16 in. less than the pipe, so that it will run through the
pipe freely. Now pull the pipe round until it just begins to flatten,
put the ball into the pipe and with some short pieces of wood, say 2
in. long by 1-1/2 in. in diam., force the ball through the dented part
of the pipe. The ball will run through all the easier if “touched” over
with a candle end. Care must be used in forcing the ball back and forth
not to drive it through the bend.
TABLE.—WEIGHT OF SHEET LEAD.
---------+-----+-----+-----+-----+-----+-----+-----+-----+-----
Inside | 3/8 | 1/2 | 5/8 | 3/4 | 1 |1-1/4|1-1/2|1-3/4| 2
Diameter | | | | | | | | |
---------+-----+-----+-----+-----+-----+-----+-----+-----+-----
| weight per foot, lbs., oz.
AAA, | 2- 8| 3- 0| 3- 8| 4-12| 6- 0| -- | -- | -- | --
AA, | 1- 8| 2- 0| 2-12| 3-12| 4-12| 6- 0| 8- 0| 8- 8| 9- 0
A, | 1- 4| 1-12| 2- 8| 3- 0| 4- 3| 4-12| 6- 8| 6- 8| 7- 0
B, | 1- 4| 1- 4| 2- 0| 2- 4| 3- 4| 3-12| 5- 0| 5- 0| 6- 0
C, | -10| 1- 0| 1- 8| 1-12| 2- 8| 3- 0| 4- 4| 4- 0| 4-12
D, | - 7| -12| 1- 0| 1- 4| 2- 0| 2- 8| 3- 8| -- | --
E, | -- | - 9| -12| 1- 0| 1-10| 2- 0| 3- 0| -- | --
Sheet lead is not the same weight,
bulk for bulk, owing to difference
in organic formation, but a cubic
foot may be said to weigh 709 lbs.
A square foot 1″ thick, 59 „
„ „ „ 1/8″ „ 7-1/2 „
„ „ „ 1/10″ „ 6 „
„ „ „ 1/12″ „ 5 „
„ „ „ 1/15″ „ 4 „
„ „ „ 1/20″ „ 3 „
Sheet lead is sometimes made as thin as writing paper.
PLUMBER’S SOLDER.
_Rule for making._—Take 100 lbs. good old lead or lead cuttings, run it
down thoroughly, stir it up and take off all dirt or dross: then take
50 lbs. pure tin, let this run down, and when nearly all is melted and
is a little cooler throw in 1/2 lb. of black rosin, and well stir the
lot up. Last bring up the heat to 600 degrees which may be known by the
burning of a bit of newspaper put in the pot. The solder is now hot
enough and should be well stirred and then run into moulds.
PLUMBER’S TOOLS.
The processes of lead working are executed by manual dexterity acquired
by long practice, and to do the work properly requires many special
tools. Some of these are used in common with other departments of
mechanics, but are none the less necessary in lead working.
We present cuts of the principal tools used, some of which are
self-explaining, and some are named with further description of
particular use.
[Illustration: Fig. 162.]
Fig. 162 represents one form of the plumber’s tap borer or reamer used
for making and enlarging holes in pipe.
[Illustration: Fig. 163.]
Fig. 163 represents plumber’s snips.
[Illustration: Fig. 164.]
Fig. 164 is the well-known and always useful ladle.
[Illustration: Fig. 165.]
Fig. 165 is the round nose pein hammer, used in plumber’s work to open
the inside pipe before jointing.
[Illustration: Fig. 166.]
Fig. 166 is the plumb bob. The same cut will also convey an idea of the
wooden instrument used to force open the pipe before jointing, _i.e._,
“the turn pin.”
[Illustration: Fig. 167.]
Fig. 167 represents “the round nose chisel.”
[Illustration: Fig. 168.]
Fig. 168 is the “wood chisel” used in cutting away wood work.
[Illustration: Fig. 169.]
Fig. 169 is the well-known “cape chisel.”
[Illustration: Fig. 170.]
Fig. 170 is the half round chisel.
[Illustration: Fig. 171.]
Fig. 171 is the equally well-known “flat cold chisel.”
[Illustration: Fig. 172.]
Fig. 172 is the “diamond point chisel.”
[Illustration: Fig. 173.]
Fig. 173 shows a rivet set for small work connected with plumbing and
sheet metal work.
[Illustration: Fig. 174.]
Fig. 174 exhibits the plumber’s torch; this is also used by engineers
to explore interiors of boilers, chimney flues, and other dark places
about the steam plant.
Fig. 175 is a compass saw.
Fig. 176 is a double-edged plumber’s saw.
Fig. 177 is a spirit level.
Fig. 178 is a looking-glass used in making underhand joints and in many
useful ways about a steam plant.
[Illustration: Fig. 175.]
[Illustration: Fig. 176.]
[Illustration: Fig. 177.]
[Illustration: Fig. 178.]
[Illustration: Fig. 179.]
Fig. 179 is a caulking tool.
[Illustration: Fig. 180.]
Fig. 180 is a gasket chisel.
[Illustration: Fig. 181.]
Fig. 181 is a soldering tool known among plumbers as “a copper pointed
bolt.”
[Illustration: Fig. 182.]
Fig. 182 is a copper-pointed bolt, flat.
[Illustration: Fig. 183.]
Fig. 183 represents a hanger, for suspending iron and lead pipe; its
excellence consists in enabling pipes to be raised or lowered after
being hung without taking the hanger apart.
USEFUL TABLES OF WEIGHTS OF IRON AND COMPARISONS OF GAUGES.
Weight of a Superficial Foot of Plate and Sheet Iron.
+------------------------------------------------------+
| PLATE IRON. |
+----------------------------+-------------------------+
| | Weight |
| Thickness. | per |
| | square foot. |
+----------------------------+-------------------------+
| INCHES. | POUNDS. |
+----------------------------+-------------------------+
| 1/16 in. | 2-1/2 |
| 1/8 „ | 5 |
| 3/16 „ | 7-1/2 |
| 1/4 „ | 10 |
| 5/16 „ | 12-1/2 |
| 3/8 „ | 15 |
| 7/16 „ | 17-1/2 |
| 1/2 „ | 20 |
| 9/16 „ | 22-1/2 |
| 5/8 „ | 25 |
| 11/16 „ | 27-1/2 |
| 3/4 „ | 30 |
| 13/16 „ | 32-1/2 |
| 7/8 „ | 35 |
| 15/16 „ | 37-1/2 |
| 1 „ | 40 |
+----------------------------+-------------------------+
| SHEET IRON. |
+----------------------------+-------------------------+
| UNITED STATES STANDARD GAUGE. |
| Adopted by Congress, to take effect July 1st, 1893. |
+---------+----------+--------------+------------------+
| NUMBER | 1000’S | WEIGHT | NEAREST |
| OF | OF | PER | FRACTION OF |
| GAUGE. | an Inch. | square foot. | an inch. |
| | | OUNCES | |
+---------+----------+--------------+------------------+
| No. 1 | .281 | 180 oz. | 9/32 in. |
| „ 2 | .265 | 170 „ | 17/64 „ |
| „ 3 | .250 | 160 „ | 1/4 „ |
| „ 4 | .234 | 150 „ | 15/64 „ |
| „ 5 | .218 | 140 „ | 7/32 „ |
| „ 6 | .203 | 130 „ | 13/64 „ |
| „ 7 | .187 | 120 „ | 3/16 „ |
| „ 8 | .171 | 110 „ | 11/64 „ |
| „ 9 | .156 | 100 „ | 5/32 „ |
| „ 10 | .140 | 90 „ | 9/64 „ |
| „ 11 | .125 | 80 „ | 1/8 „ |
| „ 12 | .109 | 70 „ | 7/64 „ |
| „ 13 | .093 | 60 „ | 3/32 „ |
| „ 14 | .078 | 50 „ | 5/64 „ |
| „ 15 | .070 | 45 „ | 9/128 „ |
| „ 16 | .062 | 40 „ | 1/16 „ |
| „ 17 | .056 | 36 „ | 9/160 „ |
| „ 18 | .050 | 32 „ | 1/20 „ |
| „ 19 | .043 | 28 „ | 7/160 „ |
| „ 20 | .037 | 24 „ | 3/80 „ |
| „ 21 | .034 | 22 „ | 11/320 „ |
| „ 22 | .031 | 20 „ | 1/32 „ |
| „ 23 | .028 | 18 „ | 9/320 „ |
| „ 24 | .025 | 16 „ | 1/40 „ |
| „ 25 | .021 | 14 „ | 7/320 „ |
| „ 26 | .018 | 12 „ | 3/160 „ |
| „ 27 | .017 | 11 „ | 11/640 „ |
| „ 28 | .015 | 10 „ | 1/64 „ |
| „ 29 | .014 | 9 „ | 9/640 „ |
| „ 30 | .012 | 8 „ | 1/80 „ |
+---------+----------+--------------+------------------+
Weight of One Foot of Round Iron.
+----------------+---------------------+
| SIZE. | Weight pr. Foot. |
+----------------+---------------------+
| | LBS. |
+----------------+---------------------+
| 1/8 in. | .041 |
| 3/16 „ | .092 |
| 1/4 „ | .164 |
| 5/16 „ | .256 |
| 3/8 „ | .368 |
| 7/16 „ | .501 |
| 1/2 „ | .654 |
| 9/16 „ | .828 |
| 5/8 „ | 1.02 |
| 11/16 „ | 1.24 |
| 3/4 „ | 1.47 |
| 13/16 „ | 1.73 |
| 7/8 „ | 2.00 |
| 15/16 „ | 2.30 |
| 1 „ | 2.62 |
| 1-1/16 „ | 2.95 |
| 1-1/8 „ | 3.31 |
| 1-3/16 „ | 3.69 |
| 1-1/4 „ | 4.09 |
| 1-5/16 „ | 4.51 |
| 1-3/8 „ | 4.95 |
| 1-7/16 „ | 5.41 |
| 1-1/2 „ | 5.89 |
| 1-9/16 „ | 6.39 |
| 1-5/8 „ | 6.91 |
| 1-11/16 „ | 7.45 |
| 1-3/4 „ | 8.02 |
| 1-13/16 „ | 8.60 |
| 1-7/8 „ | 9.20 |
| 1-15/16 „ | 9.83 |
| 2 „ | 10.47 |
| 2-1/8 „ | 11.82 |
| 2-1/4 „ | 13.25 |
| 2-3/8 „ | 14.77 |
| 2-1/2 „ | 16.36 |
| 2-3/8 „ | 18.04 |
| 2-3/4 „ | 19.80 |
| 2-7/8 „ | 21.64 |
| 3 „ | 23.56 |
| 3-1/8 „ | 25.57 |
| 3-1/4 „ | 27.65 |
| 3-3/8 „ | 29.82 |
| 3-1/2 „ | 32.07 |
| 3-5/8 „ | 34.40 |
| 3-3/4 „ | 36.82 |
| 3-7/8 „ | 39.31 |
| 4 „ | 41.89 |
| 4-1/8 „ | 44.55 |
| 4-1/4 „ | 47.29 |
| 4-3/8 „ | 50.11 |
| 4-1/2 „ | 53.01 |
| 4-5/8 „ | 56.00 |
| 4-3/4 „ | 59.07 |
| 4-7/8 „ | 62.22 |
| 5 „ | 65.45 |
| 5-1/8 „ | 68.76 |
| 5-1/4 „ | 72.16 |
| 5-3/8 „ | 75.64 |
| 5-1/2 „ | 79.19 |
| 5-5/8 „ | 82.83 |
| 5-3/4 „ | 86.56 |
| 5-7/8 „ | 90.36 |
| 6 „ | 94.25 |
+----------------+---------------------+
Weight of One Foot of Square Iron.
+----------------+---------------------+
| SIZE. | Weight pr. Foot. |
+----------------+---------------------+
| | LBS. |
+----------------+---------------------+
| 1/8 in. | .052 |
| 3/16 „ | .117 |
| 1/4 „ | .208 |
| 5/16 „ | .326 |
| 3/8 „ | .469 |
| 7/16 „ | .638 |
| 1/2 „ | .833 |
| 9/16 „ | 1.06 |
| 5/8 „ | 1.30 |
| 11/16 „ | 1.58 |
| 3/4 „ | 1.87 |
| 13/16 „ | 2.20 |
| 7/8 „ | 2.55 |
| 15/16 „ | 2.93 |
| 1 „ | 3.33 |
| 1-1/16 „ | 3.76 |
| 1-1/8 „ | 4.22 |
| 1-3/16 „ | 4.70 |
| 1-1/4 „ | 5.21 |
| 1-5/16 „ | 5.74 |
| 1-3/8 „ | 6.30 |
| 1-7/16 „ | 6.89 |
| 1-1/2 „ | 7.50 |
| 1-9/16 „ | 8.14 |
| 1-5/8 „ | 8.80 |
| 1-11/16 „ | 9.49 |
| 1-3/4 „ | 10.21 |
| 1-13/16 „ | 10.95 |
| 1-7/8 „ | 11.72 |
| 1-15/16 „ | 12.51 |
| 2 „ | 13.33 |
| 2-1/8 „ | 15.05 |
| 2-1/4 „ | 16.88 |
| 2-3/8 „ | 18.80 |
| 2-1/2 „ | 20.83 |
| 2-3/8 „ | 22.97 |
| 2-3/4 „ | 25.21 |
| 2-7/8 „ | 27.55 |
| 3 „ | 30.00 |
| 3-1/8 „ | 32.55 |
| 3-1/4 „ | 35.21 |
| 3-3/8 „ | 37.97 |
| 3-1/2 „ | 40.83 |
| 3-5/8 „ | 43.80 |
| 3-3/4 „ | 46.88 |
| 3-7/8 „ | 50.05 |
| 4 „ | 53.33 |
| 4-1/8 „ | 56.72 |
| 4-1/4 „ | 60.21 |
| 4-3/8 „ | 63.80 |
| 4-1/2 „ | 67.50 |
| 4-5/8 „ | 71.30 |
| 4-3/4 „ | 75.21 |
| 4-7/8 „ | 79.22 |
| 5 „ | 83.33 |
| 5-1/8 „ | 87.55 |
| 5-1/4 „ | 91.88 |
| 5-3/8 „ | 96.30 |
| 5-1/2 „ | 100.80 |
| 5-5/8 „ | 105.50 |
| 5-3/4 „ | 110.20 |
| 5-7/8 „ | 115.10 |
| 6 „ | 120.00 |
Weight per Running Foot of Cast Steel.
-------------+------+--------------+------
SIZE. | LBS. | SIZE. | LBS.
-------------+------+--------------+------
1/4 in. Sq.| .213| 1/4 in. Rd. | .167
1/2 „ „ | .855| 1/2 „ „ | .669
3/4 „ „ | 1.91 | 3/4 „ „ | 1.50
1 „ „ | 3.40 |1 „ „ | 2.67
1-1/4 „ „ | 5.32 |1-1/4 „ „ | 4.18
1-1/2 „ „ | 7.67 |1-1/2 „ „ | 6.02
2 „ „ |13.63 |2 „ „ |10.71
-------------+------+--------------+------
1 × 1/4 | .852| 1/2 in. Oct.| .745
1-1/8 × 3/8 | 1.43 | 5/8 „ „ | 1.16
1-1/4 × 1/2 | 2.13 | 3/4 „ „ | 1.67
1-1/2 × 5/8 | 3.19 | 7/8 „ „ | 2.28
1-3/4 × 3/4 | 4.46 |1 „ „ | 2.98
2 × 1/2 | 3.40 |1-1/8 „ „ | 3.77
„ × 5/8 | 4.25 |1-1/4 „ „ | 4.65
Comparison of Principal Gauges in use.
-------+-------------------+-------------------+-------------------
| UNITED STATES | STUBBS’ | BROWN & SHARP.
| STANDARD. | BIRMINGHAM. |
+--------+----------+--------+----------+--------+----------
Number.| | Pounds | | Pounds | | Pounds
| 1000’s |per square| 1000’s |per square| 1000’s |per square
| of | foot. | of | foot. | of | foot.
|an inch.| |an inch.| |an inch.|
| | IRON. | | IRON. | | IRON.
-------+--------+----------+--------+----------+--------+----------
No. 1 | .281 | 11.25 | .300 | 12.04 | .289 | 11.61
„ 2 | .265 | 10.62 | .284 | 11.40 | .257 | 10.34
„ 3 | .250 | 10. | .259 | 10.39 | .229 | 9.21
„ 4 | .234 | 9.37 | .238 | 9.55 | .204 | 8.20
„ 5 | .218 | 8.75 | .220 | 8.83 | .181 | 7.30
„ 6 | .203 | 8.12 | .203 | 8.15 | .162 | 6.50
„ 7 | .187 | 7.50 | .180 | 7.22 | .144 | 5.79
„ 8 | .171 | 6.87 | .165 | 6.62 | .128 | 5.16
„ 9 | .156 | 6.25 | .148 | 5.94 | .114 | 4.59
„ 10 | .140 | 5.62 | .134 | 6.38 | .102 | 4.09
„ 11 | .125 | 5.00 | .120 | 4.82 | .091 | 3.64
„ 12 | .109 | 4.37 | .109 | 4.37 | .080 | 3.24
„ 13 | .093 | 3.75 | .095 | 3.81 | .072 | 2.89
„ 14 | .078 | 3.12 | .083 | 3.33 | .064 | 2.57
„ 15 | .070 | 2.81 | .072 | 2.89 | .057 | 2.29
„ 16 | .062 | 2.50 | .065 | 2.61 | .050 | 2.04
„ 17 | .056 | 2.25 | .058 | 2.33 | .045 | 1.82
„ 18 | .050 | 2.00 | .049 | 1.97 | .040 | 1.62
„ 19 | .043 | 1.75 | .042 | 1.69 | .036 | 1.44
„ 20 | .037 | 1.50 | .035 | 1.40 | .032 | 1.28
„ 21 | .034 | 1.37 | .032 | 1.28 | .028 | 1.14
„ 22 | .031 | 1.25 | .028 | 1.12 | .025 | 1.02
„ 23 | .028 | 1.12 | .025 | 1.00 | .022 | .90
„ 24 | .025 | 1.00 | .022 | .88 | .020 | .80
„ 25 | .021 | .87 | .020 | .80 | .018 | .72
„ 26 | .018 | .75 | .018 | .72 | .016 | .64
„ 27 | .017 | .68 | .016 | .64 | .014 | .57
„ 28 | .015 | .62 | .014 | .56 | .012 | .50
„ 29 | .014 | .56 | .013 | .52 | .011 | .45
„ 30 | .012 | .50 | .012 | .48 | .010 | .40
NOISELESS WATER HEATER.
This device is very effective for heating water in open or closed tanks
by direct steam pressure without noise. The heater consists of an
outward and upward discharging steam nozzle, covered by a shield which
has numerous openings for the admission of water so that the discharge
jet takes the form of an inverted cone, discharging upwards.
[Illustration: Fig. 184.]
A small pipe admits air to the steam jet, and by mixing therewith
prevents a collapse of the steam bubbles, and the noise, which is such
a great objection to heating by direct steam in the old way. A valve
or cock on the small air pipe regulates the opening as may appear most
desirable.
Exhaust steam can by the same method be disposed of under water without
noise.
ACCIDENTS AND EMERGENCIES.
Few subjects can more usefully employ the attention and study of
engineers than the proper treatment and first remedies made necessary
by the peculiar and distressing accidents to which persons are liable
who are employed in or around a steam plant.
These and many other things of a like nature are likely to call for a
cool head, a steady hand and some practical knowledge of what is to be
done.
[Illustration: Fig. 185.]
In the first moments of sudden disaster, of any kind, the thoroughly
trained engineer is nearly always found, in the confusion incident to
such a time, to be the one most competent to advise and direct the
efforts made to avert the danger to life limb or property, and to
remedy the worst after effects.
_To fulfil this responsibility is worth much previous preparation_,
so that the best things under the circumstances may be done quickly
and efficiently. To this end the following advice is given relating to
the most common accidents which are likely to happen, in spite of the
utmost exercise of care and prudence.
=_Burns and Scalds._=—_Burns_ are produced by heated solids or by
flames of some combustible substance; _scalds_ are produced by steam or
a heated liquid. The severity of the accident depends mainly, 1, on the
intensity of the heat of the burning body, together with, 2, the extent
of surface, and, 3, the vitality of the parts involved in the injury,
thus: a person may have a finger burned off with less danger to life
than an extensive scald of his back.
The immediate effect of scalds is generally less violent than that of
burns; fluids not being capable of acquiring so high a temperature
as some solids, but flowing about with great facility, their effects
become most serious by extending to a large surface of the body. A burn
which instantly destroys the part which it touches may be free from
dangerous complications, if the injured part is confined within a small
compass; this is owing to the peculiar formation of the skin.
The skin is made up of two layers; the outer one has neither blood
vessels nor nerves, and is called the scarf-skin or cuticle; the lower
layer is called the true skin, or cutis. The latter is richly supplied
with nerves and blood vessels, and is so highly sensitive we could not
endure life unless protected by the cuticle. The skin, while soft and
thin, is yet strong enough to enable us to come in contact with objects
without pain or inconvenience.
The extent of the surface involved, the depth of the injury, the
vitality and sensibility of the parts affected must all be duly weighed
in estimating the severity and danger of an accident in any given case.
In severe cases of burns or scalds the clothes should be removed _with
the greatest care_—they should be carefully cut, at the seams, and not
pulled off.
In scalding by boiling water or steam, cold water should be plentifully
poured over the person and clothes, and the patient then be carried to
a warm room, laid on the floor or a table but not put to bed, as there
it becomes difficult to attend further to the injuries.
The secret of the treatment is to avoid chafing, _and to keep out the
air_. Save the skin unbroken, if possible, taking care not to break
the blisters; after removal of the clothing an application, to the
injured surface, of a mixture of _soot and lard_, is, according to
practical experience, an excellent and efficient remedy. The two or
three following methods of treatment also are recommended according to
convenience in obtaining the remedies.
Take ice well crushed or scraped, as dry as possible, then mix it with
fresh lard until a broken paste is formed; the mass should be put in a
thin cambric bag, laid upon the burn or scald and replaced as required.
So long as the ice and lard are melting there is no pain from the burn,
return of pain calls for a repetition of the remedy.
The free use of soft soap upon a fresh burn will remove the fire from
the flesh in a very little time, in 1/4 to 1/2 an hour. If the burn be
severe, _after relief from the burn_, use linseed oil and then sift
upon it wheat flour. When this is dried repeat the oil and flour until
a complete covering is formed. Let this dry until it falls off, and a
new skin will be formed without a scar.
In burns with lime, soap lye, or _any caustic alkali_, wash abundantly
with water (do not rub), and then with weak vinegar or water containing
a little sulphuric acid; finally apply oil, paste or mixture as in
ordinary burns.
It would be well to always keep ready mixed an ointment for burns;
in fact a previous readiness for an accident robs it of half its ill
effects.
GLUE BURN MIXTURE.
A method in use in the N. Y. City Hospital known as the “glue burn
mixture” is composed as follows: “7-1/2 Troy oz. white glue, 16 fluid
oz. water, 1 fluid oz. glycerine, 2 fluid drachms carbolic acid. Soak
the glue in the water until it is soft, then heat on a water bath until
melted; add the glycerine and carbolic acid and continue heating until,
in the intervals of stirring, a glossy strong skin begins to form over
the surface. Pour the mass into small jars, cover with parafine papers
and tin foil before the lid of the jar is put on and afterwards protect
by paper pasted round the edge of the lid. In this manner the mixture
may be preserved indefinitely.
“When wanted for use, heat in a water bath and apply with a flat brush
over the burned part.”
=_Insensibility from Smoke._=—To recover a person from this dash cold
water in the face, or cold and hot water alternately. Should this fail
turn the patient on his face with the arms folded under his forehead;
apply pressure along the back and ribs and turn the body gradually on
the side; then again slowly on the face, repeating the pressure on the
back: continue the alternate rolling movements about sixteen times a
minute until breathing is restored. A warm bath will complete the cure.
=_Heat-stroke or Sun-stroke._=—The worst cases occur where the sun’s
rays never penetrate and are caused by the extreme heat of close and
confined rooms, overheated workshops, boiler-rooms, etc. The symptoms
are: 1, a sudden loss of consciousness; 2, heavy breathing; 3, great
heat of the skin; and 4, a marked absence of sweat.
_Treatment._—The main thing is to lower the temperature. To do this,
strip off the clothing, apply chopped ice wrapped in flannel to the
head; rub ice over the chest, and place pieces under the armpits and
at the side. If no ice can be had use sheets or cloths wet with cold
water, or the body can be stripped and sprinkled with cold water from a
common watering pot.
=_Cuts and Wounds._=—In these the chief points to be attended to are:
1, arrest the bleeding; 2, remove from the wound all foreign bodies as
soon as possible; 3, bring the wounded parts opposite to each other and
keep them so; this is best done by means of strips of adhesive plaster,
first applied to one side of the wound and then secured to the other;
these strips should not be too broad, and space must be left between
the strips to allow any matter to escape. Wounds too extensive to be
held together by plaster must be stitched by a surgeon, who should
always be sent for in all severe cases.
For washing a wound, to every pint of water add 2-1/2 teaspoonfuls
of carbolic acid and 2 tablespoonfuls of glycerine—if these are not
obtainable, add 4 tablespoonsful of borax to the pint of water—wash the
wound, close it, and apply a compress of a folded square of cotton or
linen; wet it in the solution used for washing the wound and bandage
down quickly and firmly. If the bleeding is profuse, a sponge dipped in
very hot water and wrung out in a cloth should be applied as quickly as
possible—if this is not to be had, use ice or cloth wrung out in ice
water.
Wounds heal in two ways. 1, rapidly by primary union, without
suppuration, and leaving only a very fine scar. 2, slowly by
suppuration and the formation of granulations and leaving a large red
scar.
=_Bleeding._=—This is of three kinds: 1, from the arteries which lead
from the heart; 2, that which comes from the veins, which take the
blood back to the heart; 3, that from the small veins which carry the
blood to the surface of the body. In the first, the blood is bright
scarlet and escapes as though it was being pumped. In the second, the
blood is dark red and flows away in an uninterrupted stream. In the
third, the blood oozes out. In some wounds all three kinds of bleeding
occur at the same time.
The simplest and best remedy to stop the bleeding is to apply direct
pressure on the external wound by the fingers. Should the wound be long
and gaping, a compress of some soft material large enough to fill the
cavity may be pressed into it; but this should always be avoided, if
possible, as it prevents the natural closing of the wound.
Pressure with the hands will not suffice to restrain bleeding in
severe cases for a great length of time and recourse must be had to a
ligature; this can best be made with a pocket handkerchief or other
article of apparel, long enough and strong enough to bind the limb.
Fold the article neck-tie fashion, then place a smooth stone, or
anything serving for a firm pad, on the artery, tie the handkerchief
loosely, insert any available stick in the loop and proceed to twist
it, as if wringing a towel, until just tight enough to stop the flow.
Examine the wound from time to time, lessen the compression if it
becomes very cold or purple, or tighten up the handkerchief if it
commences bleeding.
Some knowledge of anatomy is necessary to guide the operator where to
press. Bleeding from the head and upper neck requires pressure to be
placed on the large artery which passes up beside the windpipe and just
above the collar bone. The artery supplying the arm and hand runs down
the inside of the upper arm, almost in line with the coat seam, and
should be pressed as shown in Fig. 185. The artery feeding the leg and
foot can be felt in the crease of the groin, just where the flesh of
the thigh seems to meet the flesh of the abdomen and this is the best
place to apply the ligature. In arterial bleeding the pressure must be
put between the heart and the wound, while in _venous_ bleeding it must
be beyond the wound to stop the flow as it goes towards the heart.
In any case of bleeding, the person may become weak and faint; unless
the blood is flowing actively this is not a serious sign, and the quiet
condition of the faint often assists nature in staying the bleeding, by
allowing the blood to clot and so block up any wound in a blood vessel.
Unless the faint is prolonged or the patient is losing much blood, it
is better not to hasten to relieve the faint condition; when in this
state anything like excitement should be avoided, external warmth
should be applied, the person covered with blankets, and bottles of hot
water or hot bricks applied to the feet and arm-pits.
=_Frost-bite._=—No warm air, warm water, or fire should be allowed near
the frozen parts until the natural temperature is nearly restored; rub
the affected parts gently with snow or snow water in a cold room; the
circulation should be restored very slowly; and great care must be
taken in the after treatment.
=_Broken Bones._=—The treatment consists of, 1, carefully removing
or cutting away, if more convenient, any of the clothes which are
compressing or hurting the injured parts; 2, very gently replacing the
bones in their natural position and shape, as nearly as possible, and
putting the part in a position which gives most ease to the patient; 3,
applying some temporary splint or appliance, which will keep the broken
bones from moving about and tearing the flesh; for this purpose, pieces
of wood, pasteboard, straw, or firmly folded cloth may be used, taking
care to pad the splints with some soft material and not to apply them
too tightly, while the splints may be tied by loops of rope, string, or
strips of cloth; 4, conveying the patient home or to a hospital.
The bearer then places his arm behind the back of the patient and
grasps his opposite hip, at the same time catching firmly hold of the
hand of the patient resting on his shoulder, with his other hand; then
by putting his hip behind the near hip of the patient, much support is
given, and if necessary, the bearer can lift him off the ground and as
it were, carry him along.
=_Poultices._=—These outward applications are useful to relieve
sudden cramps and pains due to severe injuries, sprains and colds.
The secret of applying a mustard is to apply it hot and keep it so by
frequent changes—if it gets cold and clammy it will do more harm than
good. Poultices to be of any service and hold its heat should be from
one-half to one inch thick. To make it, take flaxseed, oatmeal, rye
meal, bread, or ground slippery elm; stir the meal slowly into a bowl
of boiling water, until a thin and smooth dough is formed. To apply it,
take a piece of old linen of the right size, fold it in the middle;
spread the dough evenly on one half of the cloth and cover it with the
other.
To make a “mustard paste” as it is called, mix one or two
tablespoonfuls of mustard and the same of fine flour, with enough water
to make the mixture an even paste; spread it neatly with a table knife
on a piece of old linen, or even cotton cloth. Cover the face of the
paste with a piece of thin muslin.
=_How to Carry an Injured Person._=—In case of an injury where walking
is impossible, and lying down is not absolutely necessary, the injured
person may be seated in a chair, and carried; or he may sit upon a
board, the ends of which are carried by two men, around whose necks he
should place his arms so as to steady himself.
Where an injured person can walk he will get much help by putting his
arms over the shoulders and round the necks of two others.
A seat may be made with four hands and the person may be thus carried
and steadied by clasping his arms around the necks of his bearers.
If only one person is available and the patient can stand up, let him
place one arm round the neck of the bearer, bringing his hand on and in
front of the opposite shoulder of the bearer.
To get at a broken limb, or rib, the clothing must be removed, and
it is essential that this be done without injury to the patient; the
simplest plan is to rip up the seams of such garments as are in the
way. Boots must be cut off. It is not imperatively necessary to do
anything to a broken limb before the arrival of a doctor except to keep
it perfectly at rest.
To carry an injured person by a stretcher (which can be made of a
door, shutter, or settee—with blankets or shawls or coats for pillows)
three persons are necessary. In lifting the patient on the stretcher
_it should be laid with its foot to his head_, so that both are in the
same straight line; then one or two persons should stand on each side
of him, and raise him from the ground, slip him on the stretcher; this
to avoid the necessity of any one stepping over the stretcher, and the
liability of stumbling. If a limb is crushed or broken, it may be laid
upon a pillow with bandages tied around the whole (_i.e._, pillow and
limb) to keep it from slipping about. In carrying the stretcher the
bearers should “break step” with short paces; hurrying and jolting
should be avoided and the stretcher should be carried so that the
patient may be in plain sight of the bearers.
PERSONAL.
_The fireman, so called, in steam service of any description, should
and does on the average receive double the compensation of a man who
has only his labor to bargain for._
_In addition, he exercises his skillful vocation in sheltered places
and is almost the last of the employees of a plant to be “laid off” and
is certainly the first to be called on again after stoppage._
_Still further, the fireman has an almost equal opportunity, with
the best shop trained machinist, for advancement to the position of
engineer in charge of the most extensive steam plants._
_Now! this increased pay over ordinary labor and other numerous
advantages accruing from the position, demand a generous return, and
in ending this work, the author suggests these “points” for observance
to the aspiring student, whether engineer, fireman, or machinist,
namely—that sobriety should be held one of the first elements of strict
observance; an unresting tidiness of person and premises; dignity of
conduct, as being owed to the rising profession of steam engineering;
and lastly, an unswerving fidelity of trust, which may include honesty,
truthfulness and courage._
INDEX
FOR
MAXIMS AND INSTRUCTIONS.
=Accidents and Emergencies=, 313.
Factory rules to prevent, 293.
Government rules to prevent, 290.
=Acid=, definition, 137.
=Advantages= of triple draught tubular boiler, 84.
=Air= used in burning 1 lb. of coal, 14.
ditto, how supplied to the coal, 14.
Description, 16.
As a material substance, 16.
Density at different depths, 16.
Weight of a column of air, 17.
As a fluid, 17.
As an impenetrable body, 17.
Five “points” for the engineer, 17.
Composition of, 17.
Specific heat of, 215.
=Air valve=, use of, 255.
=Alcohol=, specific heat of, 214.
=Alkalies=, definition, 137.
=Alum=, boiling point of, 37.
=Ammoniac (Sal)=, boiling point of, 37.
=Analysis= of anthracite coal, 13.
Of bituminous coal, 13.
Of wood, 13.
Of heat, 13.
Of scale deposited in marine boilers, 146.
Of feed waters, 139-140.
=Angle= and T iron, dimensions and shape, 104.
=Angle brick=, 237.
=Angle-valve=, description, 273.
=Anthracite coal=, analysis of, 13.
Ignited with difficulty, 16.
=Antimony=, melting point, 42.
=Answers= of applicants for a marine license, 127.
=Arch-brick=, 237.
=Area of safety valve=, rule for finding, 192.
=Ash pit=, the, 238.
How kept during firing, 27.
=Assistant engineers=, classification of, 310.
=Back pressure valves=, description, 273.
=Baffle plate=, description, 169, 180.
=Ball valve=, description, 273.
=Bark=, effect on steam boilers, 151.
=Barrel=, rule for finding contents of, 203.
=Bars=, grate, description, 173.
=Before lighting the fire=, directions, 25.
=Belts=, how to safely run on pullies, 291.
=Bending= lead pipe, 304.
=Bib cock=, description, 273.
=Bituminous coal=, analysis of, 13.
How burned, 16.
=Blast pipe= for marine boiler, 63.
=Bleeding=, treatment of, 317.
=Blowers= for shavings, 20.
=Blow off=, description, 81.
Surface, description, 161.
=Boilers=, description, 48.
Upright steam, 50.
Crude form, 52.
Plain cylinder, description, 52.
Cornish, description, 54.
Lancashire, description, 55.
Galloway, description of, 58.
Marine, description of, 60.
Marine, table of dimensions, 62.
Locomotive portable, 80.
Construction of, 89.
Caulking, 94.
Dangers from syphoning, 288.
Dangers from gas, 288.
Foaming in, 42.
Fulcring, 94.
Horse power of, 234.
Proper steam connection for, 276.
=Boiler braces=, “points” relating to, 104.
=Boiler coverings=, 273.
=Boiler=, Compound, composition of, 151-152.
Compound, for locomotives, 149.
=Boiler castings=, specification of, 86.
=Boiler cleaners=, mechanical description, 159, 160.
=Boiler explosions=, causes of, 286.
=Boiler fittings= and mountings, 87.
Fixtures, description, 164.
=Boiler flue brushes=, use of, 21.
=Boiler fronts=, description, 165.
=Boiler injector=, description, 206.
=Boiling=, process of, 37.
=Boiling points= of various substances, 37.
=Boiler maker’s= tools and machinery, 281.
=Boilers newly set=, how fired, 28.
No two alike, 25.
=Boiler and pipe covering=, mixtures for, 275-276.
=Boiler plates=, example of riveting, 114.
Marks on, 88.
=Boiler repairs=, 123.
Note, 125.
=Boiler scale=, analysis of, 148.
=Boiler scum=, how formed, 150.
=Boiler setting=, 236.
=Boiler steel=, description of quality, 90.
=Boiler tubes=, dimensions of lap welded tubes, 110.
Table of holding power, 111.
Experiments in strength of, 111.
Notes, 110, 112.
Illustration of size, 245.
=Boiler testing=, specification, 87.
=Bolts=, strain on, rule, 99.
Socket, description, 103.
=Bolt=, plumber’s copper pointed, 308.
=Bones=, broken, treatment of, 318.
=Borer=, tap, plumber’s, 306.
=Box coil=, description, 257.
=Brace=, difference between, and stay, 103.
Head to head, description, 103.
Crow foot, 103.
=Braces=, shop names for, 103.
Table for calculations, 107-109.
Table of diameters, 103.
Inspector’s rules, 102.
Specification for, 86.
“Points” relating to, 104.
=Bracing= of steam boilers, 96.
=Bracket=, valve, description, 272.
=Brass=, conducting power of, 213.
=Brick=, furnace, 237.
=Brine valve=, description, 277.
=Broken bones=, treatment of, 318.
=Burns and scalds=, treatment of, 313.
=Burn mixture=, 315.
=Bushing=, description, 274.
=Butt joint=, illustration, 115.
=Calculations= relating to steam heating, 262.
Relating to pumps, 22.
Relating to safety valves, 191.
=Calipers=, use of, 22.
=Cape chisel=, 307, 281.
=Carbon=, description of, 229.
=Carbonate=, definition, 136.
Of magnesia, definition, 138.
Of lime, at what temperature deposited, 148.
=Carbonic acid=, in water how detected, 153-154.
Specific heat of, 215.
=Carbonic acid gas=, description of, 230.
=Carbonic oxide=, description of, 231.
Specific heat of, 215.
=Carbonization=, method of, 15.
=Care and management= of the steam boiler, 24.
=Care of steam fittings=, 268.
=Care of water tube boilers=, 70.
=Castings=, for boiler, specification, 86.
=Caulking=, description, 94.
=Caulking tools=, plumber’s, 308.
=Certificates of Inspection=, issuing of, 131.
=Chain riveting=, example, 93.
=Chapter of “Don’ts,”= 44-47.
=Charcoal=, description, 15.
Specific heat of, 214.
=Charcoal Iron=, description, 88.
=Check valve=, description, 273.
=Chemical terms= relating to feed water, 136.
=Chemistry=, definition, 136.
=Chemistry of the furnace=, 226.
=Chief engineers=, classification of, 310.
=Chimney= draught, 296.
=Chisel=, cold, 307.
Cape, 307.
Round nose, 307.
Half round nose, 307.
Wood, 307.
Diamond nose, 307.
Gasket, 308.
=Chloride=, definition, 137.
=Chlorides=, how indicated in water, 157.
=C. H. No. 1 F=, 88.
=C. H. No. 1 FB=, 88.
=Circle brick=, 237.
=Circulation=, water, 294.
=Cisterns=, capacity of, 202.
=Clamp=, boiler, description and cut, 123.
=Classification of marine engineers=, 310.
=Cleaners=, mechanical boiler, description, 159-180.
=Cleaning out boilers= under firing, 20.
=Coal tar=, how best fired, 30.
=Coal=, 13.
What it consists of, 13.
Common proportions, 13.
Introduction of air in burning, 13.
Bituminous, how it burns, 16.
Anthracite, how it burns, 16.
Comparative evaporation, 18.
Specific heat of, 214.
Storing and handling of, 225.
=Cocks,= description, 270.
Valve, description, 272.
Gauge, description, 170.
Bib, description, 273.
Three way, description, 273.
Four way, description, 273.
=Coil=, box, description, 257.
Pipe, description, 257.
=Coke=, description, 15.
Comparative evaporation, 18.
Ratio between heating and grate surface, 28.
How best fired, 28.
Specific heat of, 214.
=Cold chisel=, 307.
=Cold short=, definition, 121.
=Columns=, glass water gauge, 177.
=Combustible= parts of coal, 16.
=Combustion=, operation on materials, 16.
Chamber, 238.
Chambers of marine boilers, 62.
=Compasses=, use of, 22.
=Compass saw=, 308.
=Compound=, boiler, composition, 151-2.
For locomotive boilers, 149.
=C No. 1=, iron, 88.
=Condenser=, surface description, 65.
Operation of, 66.
=Conducting power= of various substances, 213.
=Conical head= of rivets, description, 113.
=Construction= of boilers, description, 89.
And drawing rivet heads, 113.
=Contraction of area=, definition, 121.
=Conveyors=, screw, 20.
=Copper=, conducting power of, 213.
Radiating power of, 213.
Specific heat of, 214.
=Cornish boiler=, description of, 54.
Defects of, 54.
=Corrosion= of steam boilers, 126, 142, 144.
=Coverings= for pipes and boilers, 275.
=Coupling=, description, 274.
For pipe, 250.
=Cracks= in boilers, how to repair, 123.
=Cross T=, description, 274.
=Crowfoot brace=, 103.
=Cup head= of rivets, description, 118.
=Cutaway front=, description, 165-167.
=Cuts and wounds=, treatment of, 316.
=Cylinder boiler=, description, 52.
Defects of, 53.
=Dampers= and doors to the furnace, 39.
=Damper regulators=, description, 185.
=Danger=, points, in steam boiler, 125.
=Dart=, description and cut, 19.
=Dead end= of pipe, 284.
=Dead plate=, description, 180, 237.
=Dead steam=, description, 282.
=Dedication=, 5.
=Defects=, table of, 125.
=Defects= and necessary repairs to boilers, 123.
=Definition of Terms=, 121.
=Designing boilers=, relating to stayed surfaces, 99.
=Device= for using kerosene oil, 158.
=Diamond nose chisel=, 307.
=Directions= before lighting the fire, 25.
For firing with various fuels, 27.
=Disc= for boiler makers, 281.
“=Don’ts=,” a chapter of, 44-47.
=Doors=, furnace, description, 168-170.
=Double seat valve=, description, 273.
Also see Fig. 158.
=Drain=, the steam, description, 81.
=Drainage and piping=, description and illustration, 299.
=Drain cock=, description, 181.
=Draughts=, at time of lighting the fire, 26.
Of chimney, 296.
Regulating the draught, 41.
=Drawings= of rivet heads, 118.
=Drum=, mud, description, 179.
=Dry steam=, description, 282.
=Ductile=, definition, 121.
=Dudgeon expanders=, description, 281.
=Duties of the fireman=, 27.
=Duty of boiler=, specification, 87.
=Dust= (coal), firing of, 40.
=Economizer=, fuel, description, 185.
=Elasticity=, definition, 121.
=Elastic limit=, definition, 121.
=Elbow=, description, 274.
=Element=, definition, 136.
=Ell=, description, 274.
=Elongation= of steel plate, 90.
Definition, 121.
=Ether=, specific heat of, 214.
=Engineer’s questions=, 133.
Examinations, “points,” 133.
Tests for impurities in water, 153.
=Evans, Oliver.=, viii.
=Examination= of engineers, 133.
=Exhaust steam= heating, 267.
=Expanders= (dudgeon), 281.
=Expansion= (linear), of steam pipe, 270.
=Explosions=, boiler, 286.
Of steam pipe, 287.
=Factory rules= to prevent accident, 293.
=Fatigued=, definition, 121.
=Feed water=, analysis of, 139-140.
Engineer’s tests, 153.
A precipitator for sea water, 146.
Examples of analysis, 140-141.
Preliminary precipitation, 144.
Description, 196.
Heaters, “points” relating to, 201.
Heaters, table of savings, 200.
Purifier, description, 185.
=Fire=, thickness of, 40.
What to do in case of, 40.
=Fire box iron=, description, 88.
=Fire brick arch= in locomotive, 35.
=Fire clay=, conducting power of, 213.
=Fire door=, 237.
=Fire irons=, 21.
=Firemen=, advantages of trained, 24.
=Fire pails=, use of, 21.
=Firing=, trick of, 24.
Boilers newly set, 28.
With straw, description, 31.
Duties of the fireman, 27.
Ocean steamer, description, 32.
Improper method, 27.
Proper method, 26.
With oil, description, 32.
With coal tar, description, 30.
Of twenty horse power, description, 30.
Sixteen steam boilers, description, 29.
With shavings, 33.
With coke, directions, 28.
Of steam boilers, 24.
Under a boiler, gases and solids produced, 16.
With saw dust, 33.
A new plant, 37.
With coal dust and screenings, 40.
=Firing= with tan bark, 36.
Boilers, experiments in England, 40,
A locomotive, 35.
=Files=, use of, 21.
=Fish trap=, 205.
=Fittings= of marine boilers, 63.
For boiler, specification, 87.
=Fixtures=, boiler, description, 164.
=Flame=, luminous, 41.
Of anthracite coal, 16.
=Flange iron=, description, 88.
=Flange of boiler head=, proper radius, 103.
=Flanges= for pipe, 248.
=Flanges=, how to be turned, etc., 85.
=Flat surfaces= in boilers, how to stay, 98.
=Flues and tubes=, sweeping, 39.
=Flush front=, description, 165-166.
=Foaming in boilers=, 42.
=Four way cock=, description, 273.
=Fronts=, boiler, description, 165.
=Frost-bite=, treatment of, 317.
=Fuel=, loss of, by incrustation, 143.
=Fuel economizer=, description, 185.
=Fuel-oil=, 289.
Rules relating to, 290.
=Fuels=, liquid and gas, 15.
Table of comparative evaporative value, 18.
=Fullering=, description, 94.
=Fulton, Robert=, viii.
=Furnace=, temperature of, 42.
Fire, kindling of, 241.
Chemistry of, 229.
Dampers and doors, 39.
Doors, description, 168-170.
The, 237.
=Fusible plugs=, description, 171, 172.
=Galloway boiler=, description of, 58.
Table of dimensions, 60.
=Gas=, difference between it and a liquid, 216.
As a fuel, 15.
From coal, comparative evaporation, 18.
Dangers from, in idle boilers, 288.
Amount burned in ventilating pipes, 265.
=Gasket= chisel, 308.
=Gas pipe=, illustrations of size, 243.
=Gas pliers=, description, 269.
=Gate valve=, description, 273.
=Generators=, steam, description, 48.
=Glass=, specific heat of, 214.
Radiating power of, 213.
=Glass gauges=, description, 177.
=Glass water gauge columns=, 177.
=Globe valve=, description, 272.
=Gold=, radiating power of, 213.
Conducting power of, 213.
=Grate=, the, 237.
=Grate bars=, description, 173.
How to preserve from excessive heat, 38.
Shaking grates, 174.
How kept during firing, 27.
=Grooving= of steam boilers, 126.
List of cases, 125.
=Growth= of the steam boiler, 52.
=Gauge=, steam, description, 181.
=Gauge cocks=, description, 176.
=Gauges=, glass, description, 177.
=Gauges=, pressure recording, description, 233.
=Gusset stays=, description, 100, 103.
=Hammer=, water, description, 283.
Pein, 306.
=Hammer test= of rivets, 95.
=Hand-hole plates=, description, 81.
=Hanger= for pipes, 308.
=Hazards= of fuel-oil, 289.
Of the boiler room, 285.
=Heads of rivets=, cup, conical, pan heads, 113.
=Head to head= brace, description, 103.
=Heat=, laws of, 212.
Unit of, 214.
Specific, 214.
How it becomes effective, 13.
=Heaters=, feed water, description, 196.
=Heating=, steam and hot water, 251.
By exhaust steam, 267.
=Heat proof paints=, 232.
=Heat stroke=, treatment of, 315.
=High pressure steam=, 283.
=Hinged valves=, description, 272.
=Hoes=, use of, 21.
=Homogeneous=, definition, 121.
=Horizontal tubular boiler=, description, 79.
Parts of, 81.
Table of sizes, 77.
=Horse power=, rule for estimating, 235.
As applied to boilers, 234.
=Hose=, rubber, use of, 21.
=Hot short=, definition, 122.
=How to carry= injured persons, 319.
=How to prepare= for inspection of steam boilers, 130.
=Hydrogen=, specific heat of, 215.
Description of, 230.
=Hydraulic test=, 131.
=Ice=, radiating power of, 213.
Specific heat of, 214.
=Improper method of firing=, cuts and description, 27.
=Incrustation= of steam boilers, 142-144.
Example of, 142.
And scale, list of cases, 125.
Table showing quantity collecting, 103.
Of boilers, “points” relation to, 149-152.
=Individuality= of each steam boiler, 25.
=Injector=, description, 206.
=Injured persons=, how to carry, 319, 320.
=Inspection= of steam boilers, 129.
How to make ready for, 129-130.
=Inspector’s questions= to applicant, 128.
=Inspector’s rules= relating to braces, 102.
=Interceptor=, steam, description, 183.
=Introduction=, 10.
=Iron=, T, description of, 103.
(Hammered), melting point, 42.
(Wrought), melting point, 42.
Fire box, description, 88.
Charcoal iron, description, 88.
(Wrought), conducting power of, 213.
Polished, radiating power of, 213.
Specific heat of, 214.
Melting point, 42.
Flange, description, 88.
Cast, conducting power of, 213.
=Irons=, fire, 21.
=Issuing certificates= of inspection, 131.
=Jackscrews=, description, 281.
=Jam brick=, 237.
=Joints=, putty, how to make, 303.
=Joints of lead pipe=, 300.
=Joints of pipes=, 248.
=Kerosene oil= in boilers, “points” of, 156-7.
=Kindling a furnace fire=, 241.
=L=, description, 274.
=Lace cutters=, use of, 21.
=Ladders=, use of, 21.
=Ladle=, 306.
=Lamp black=, radiating power of, 213.
=Lancashire boiler=, description, 55.
Defects of, 55.
=Language= of steam boilers, 39.
=Lanterns=, use of, 21.
=Lap joint=, illustration, 115.
=Laws= of heat, 212.
=Lazy bar=, description, 20.
=Lead=, 299.
Advantages in use of, 299.
Melting point, 42.
Conducting power of, 213.
Wrought, radiating power of, 213.
Specific heat of, 214.
Polished, radiating power of, 213.
=Lead pipe=, how to make putty joints, 304.
Table of sizes and weights, 305.
How to bend, 304.
=Lead pipe joints=, 300.
=Lever=, length, rule, 193.
=Lifting valves=, description, 273.
=Lime=, definition, 138.
=Liquid=, difference between it and a gas, 216.
=Litmus paper=, definition, 153.
=Live steam=, description, 282.
=Locknut=, description, 274.
=Locomotive=, firing of, 35.
Boiler Compound, 149.
Or charging shovel, description, 19.
=Locomotive boilers=, description, 72.
How to rivet, 115.
=Locomotive= portable boiler, description, 80.
=Looking glass=, 307.
=Loop=, (steam), description of, 278-280.
=Low pressure steam=, 283.
=Lugs=, specification of, 86.
=Luminous flame=, 41.
=Magnesia=, definition, 138.
At what temperature deposited, 148.
Carbonate of, definition, 138.
=Malleable=, definition, 121.
=Manhole cover=, description, 81.
=Manhole plates=, specification, 86.
=Marine boilers=, description of, 60.
How to rivet, 115.
Fittings for, 63.
Table of dimensions, 62.
Super heaters, 64.
Use of zinc in, 162.
Blast pipe for, 63.
Uptakes, 64.
Parts which first give way, 112.
Incrustation and scaling of, 146-147.
=Marine engineers= classification of, 310.
Rules relating to, 309.
=Marks= on boiler plates, 88.
=Marble=, conducting power of, 213.
=Materials=, 12, 13.
=Mechanical scrapers=, 187.
=Mechanical stokers=, 134-135.
=Mercury=, specific heat of, 214.
Radiating power of, 213.
=Meters=, water, description, 203.
=Moisture=, in wood, 14.
=Mouth piece=, furnace, 236.
=Mud drum=, description, 179.
=Newly set boilers=, how fired, 28.
=Nickel steel= boiler plates, description, 91.
=Nipple=, description, 274.
=Nitric acid=, boiling point of, 37.
=Nitrogen=, specific heat of, 215.
Description of, 230.
=Non-conductors=, 276.
=Noiseless water-heater=, 312.
=Ocean steamer=, how to fire, 32.
=Oil=, fuel, 289.
Kerosene, in boilers, “points” of, 156-157.
Specific heat of, 214.
Firing with, 32.
=Ore barrow=, use of, 20.
=Organic matter= in water, how indicated, 154.
=Ornamental paints=, 232.
=Overhanging front=, description, 165-167.
=Overhead system= of heating, 256.
=Oxide=, definition, 136.
Of iron how best treated, 148.
=Oxygen=, description of, 229.
Specific heat of, 215.
United with coal, 17.
=Paints=, heat proof, 232.
=Palm stays=, description, 100.
=Pan head= of rivets, description, 113.
=Patch-screw=, description and cut, 123.
=Peat=, description, 14.
Analysis of, 13.
Charcoal, description, 15.
Comparative evaporation, 18.
=Pein hammer=, 306.
=Petroleum=, as a fuel, 15.
Oil, comparative evaporation, 18.
In boilers, use of, 155.
=Philadelphia Water Works= example of gain in good firemen, 25.
=Pipes=, table of surfaces and capacities, 246.
Joints of, 248.
How to weld, 264.
Used for ice machinery, 263.
Table of “data” relative to, 247.
=Pipes and piping=, description, 244.
=Pipe coil=, description, 257.
=Pipe couplings=, 250.
=Pipe cutter=, description and cut, 269.
=Pipe hanger=, 308.
=Pipe=, gas, illustration of size, 243.
=Pipe tongs=, description, 269.
=Pipe union=, description, 274.
=Piping=, dead end, 284.
=Piping and drainage=, description and illustration, 209.
=Pitting=, of steam boilers, 126.
=Planer=, (power), for boiler makers, 281.
=Plate=, dead, description, 180.
Quality of steel, 90.
=Plates=, baffle, description, 180.
Burned and blistered, list, 125.
For boilers, table of thicknesses, 113.
=Pliers=, gas, description, 269.
=Plug=, description, 274.
=Plugs=, fusible, description, 171-172.
=Plumb-bob=, description, 306.
=Plumber’s solder=, how to make, 305.
=Plumber’s tools=, description, 306-309.
Solder, rule for making, 305.
=Plumber’s wipe joint=, 298.
=Plumbing=, description and cuts, 298.
What engineers should know, 298.
“=Points=” relating to firing, 37.
Relating to boiler braces, 104.
Of danger in steam boiler, 125.
Relating to grate bars, 175.
Relating to water gauge cocks, 176.
Relating to glass gauges, 177.
Relating to the steam gauge, 182.
Relating to safety valves, 194.
Relating to feed water heaters, 201.
Relating to water meters, 204.
Relating to injectors, 209.
Relating to pumps, 218-221.
Relating to boiler setting, 239-241.
Relating to steam heating, 254.
Relating to chimneys and draught, 297.
=Poker=, description and cuts, 19.
=Portable= boiler, locomotive, description, 80.
Car track, use of, 20.
=Potter, Humphry=, inventor of valve motion, 270.
=Poultices=, how to make, 319.
=Power planer= for boiler makers, 281.
=Power punch= for boiler makers, 281.
=Precipitation= of impurities in feed water, 144.
=Preface=, 7.
=Preparation= for firing steam boilers, 24.
=Pressure gauges=, list of defective cases, 123.
Regulator valve, 274.
=Pressure of safety valve=, rule, 192.
=Principles= relating to water, 223.
=Proper method of firing=, cut and description, 21.
=Punch= for boiler makers, 281.
=Pump=, description, 215.
Classification, 217.
Parts of, Illustration, 218.
Double acting, 218.
Direct pressure, 216.
Calculations relating to, 222.
Strainer, for, description, 223.
Points relating to, 218-221.
=Putty joints=, how to make, 303.
=Questions= of applicant for marine license, 127.
Asked by examining engineers, 309.
Of proprietor, relating to steam boiler, 127.
=Radiant rays= of heat, “point,” 38.
=Radiating power= of various substances, 213.
=Radiation of heat=, law relating to, 39.
=Railroad barrow=, use of, 20.
=Ram=, water, 284.
=Ratio= of grate to heating surface, 175.
=Re-agent=, definition, 136.
=Reamer=, plumber’s, 306.
=Recording pressure gauges=, description, 233.
=Reducing= coupling, description, 274.
=Regulating= the draught, 41.
=Regulations= relating to marine engineers, 309.
=Regulators=, damper, description, 185.
=Relief valve=, description, 272.
=Repairing= leaky tubes, 126.
=Repairs= to boilers, “points” on, 124-6.
=Riveting=, modes of, 93.
Specification for, 86.
Description, 91.
Double description, 91.
Chain, example, 93.
Zig-Zag, example, 93.
Treble, example, 93.
Unequal pitches, example, 93.
Example of riveting boiler plates, 114-116.
Hammers for boiler makers, 281.
List of defective cases, 125.
=Rivet heads= of cup, conical, pan heads, 113.
=Rivet heating machines=, 261.
=Rivets=, description, 93.
Steel, description, 95.
Table of diameters, 113.
=Rivet set=, 307.
Tests, 95.
=Riveted stays=, description, 106.
=Rolls= for boiler makers, 281.
=Rotary valves=, description, 273.
=Round nose chisel=, 307.
=Rubber hose=, use of, 21.
=Rule= for estimating horse power of boilers, 235.
For finding area of valve opening, 195.
To find pressure in lbs. of column of water, 222.
To find area of steam piston of pump, 222.
To find quantity of water elevated, 222.
For finding contents of a barrel, 203.
For reading water meters, 204.
For making boiler and pipe covering, 275-276.
For making solder, 305.
For finding strain on bolts, 99.
For safe internal pressure, 117.
For determining areas of steam boilers, 105.
For calculating contents of steam and water in
the steam boiler, 105.
=Rules=, U. S., regarding safety valves, 189.
For safety valves, 193.
Inspectors, relating to bracing, 102.
Relating to fuel oil, 290.
Factory, to prevent accident, 293.
Government, to prevent accident, 290.
Before lighting the furnace fire, 25.
=Running= of steam boilers under fire, 24.
=Safe internal pressure=, rule and example, 117.
Tables, 118-120.
=Safety factor= of steam boilers, 96.
=Safety valves=, description, 187.
Rules, 191, 193.
Rule to find area of opening, 195.
Table showing rise of valve, 195.
List of defects, 125.
Points relating to, 194.
=Salt=, definition, 138.
=Sand-bending= of lead pipe, 304.
=Saturated steam=, 283.
=Saw=, compass. 308.
Plumber’s, 307.
=Saw dust=, firing with, 33 , 242.
As a fuel, 16.
=Sea water= precipitator, 145.
=Sectional steam boilers=, description, 71.
=Sentinel valve=, description, 184.
=Separator=, steam, description, 183.
=Set screws=, dangers arising from, 292.
=Setting= of steam boilers, 236.
Of water tube boilers, 239.
=Scalds=, treatment of, 313.
=Scale= deposited in marine boilers, analysis, 146-147.
Boiler, analysis of, 148.
=Scaling= of steam boilers, “points,” 149-152.
=Scope of the work=, 12.
=Scoop shovel=, cut and description, 19.
=Scrapers=, mechanical, 187.
=Screenings=, firing of coal dust and, 40.
=Screw conveyors=, use of, 20.
=Screw-jacks=, use of, 21.
=Screw stays=, description, 101.
=Scum= of boilers, how formed. 150.
=Scumming apparatus=, description, 161.
=Shaking grates=, description, 174.
=Shavings=, firing with, 33.
Blowers, use of, 20.
=Shearing strength=, definition, 121.
=Shears= for boiler makers, 281.
=Shell= of boiler, description, 81.
=Shovels=, cut and description of, 19.
=Side brackets= for boilers, 240.
=Silica=, definition, 137.
=Silver=, radiating power of, 213.
Conducting power of, 213.
Melting point, 42.
=Six inch flue=, boiler, 78.
=Slice bar=, description and cuts, 19.
“Point” relating to its use, 30.
=Smoke=, insensibility from, treatment, 315.
=Snips=, plumber’s, 306.
=Socket bolts=, description, 103.
=Soda=, definition, 138.
Proportion of, in water, 154.
Acetate of, boiling point of, 37.
=Sodium=, definition, 138.
=Solder=, rule for making plumber’s, 305.
=Sounds=, or language of steam boilers, 39.
=Source of power= in the steam engine, 13.
=Specifications= for 125 H. P. steam boiler, 85.
=Specific heat=, description, 214.
Table, 214.
=Spectacle piece=, 124.
=Spirit level=, 307.
=Stay bolts=, hollow, description, 103.
=Staying= of flat surfaces, 98.
=Stays and braces=, list of defective cases, 125.
=Stays=, gusset, description, 100.
Of marine boilers, 75.
Of locomotive boilers, 75.
“Points” relating to boiler stays, 104.
Palm, description, 100.
Screwed, description, 101.
And brace, difference, 103.
Table for calculations, 107-109.
=Steam=, description, 282.
Specific heat of, 215.
Dry, 282.
Dead, 282.
Live, 282.
Saturated, 283.
Wet, 283.
High pressure, 283.
Low pressure, 283.
Superheated, 283.
Specific gravity of, 283.
Total heat of, 283.
=Steam and hot water heating=, 251.
=Steam boiler=, growth of the, 52.
Water tube, 67.
Sectional, description of, 71.
Triple draught, 81-82.
Six-inch flue, 78.
Two-flue, 78.
=Steam boilers=, locomotive, 72.
Idle, dangers of, 288.
Inspector’s rules relating to bracing of, 102.
Use of petroleum in, 155.
Effect of sugar on, 150.
Corrosion and incrustation, 142.
Scaling of, “points,” 149-152.
Effect of bark on, 151.
Bracing, 96.
Specification for 125 H. P., 85.
=Steam drum= or dome, description, 81.
=Steam fitter’s vise=, 269.
=Steam fittings=, care, 268.
Description, 274.
=Steam gauge=, description, 181.
=Steam generators=, 48.
=Steam heating= by exhaust, 267.
How much space 1 H. P. will heat, 262.
=Steam loop=, note relating to, 295.
Description, 278-280.
=Steam pipe=, linear expansion of, 276.
=Steam pipe explosions=, 287.
=Steam pump=, 215.
=Steam separator=, description, 183.
=Steam space of boilers=, rule and example, 105.
=Steam whistle=, description, 180.
=Steel rivets=, description, 95.
=Steel=, boiler, description, 90.
Melting point, 42.
Specific heat of, 214.
=Steel plates=, nickel steel, description, 91.
Quality and thickness in, 85.
Quality of, 90.
=Stephenson, George=, viii.
=Stock and dies=, use of, 21.
=Stoker=, mechanical, 134.
=Storing coal=, 225.
=Straightway valve=, description, 273.
=Strainer=, for pump, description, 223.
=Strain on bolts=, rule and example, 99.
=Straw=, how best fired, 31.
Composition of, as fuel, 15.
=Sugar=, effect of, on steam boilers, 150.
=Sulphates=, how indicated, 154.
Definition, 137.
=Sulphate of lime=, at what temperature deposited, 148.
=Sulphur=, description of, 230.
=Sulphuric acid=, boiling point of, 37.
=Sunstroke=, treatment of, 315.
=Superheated steam=, 283.
=Superheater= of marine boiler, 64.
=Surface blow off=, description, 161.
=Surface condenser=, description, 65.
=Swing valve=, description, 273.
=Syphon=, dangers from, in boilers, 288.
=T=, description, 274.
=T irons=, description and use, 103.
Dimensions and shape, 104.
=Table= of evaporation, 18.
Melting points of metals, 42.
Temperature, judged by color, 42.
Of dimensions, Galloway boiler, 60.
Of marine boilers, 62.
Diameter of braces, 103.
For calculating the number of stays, 107-109.
Of dimensions of boiler tubes, 110.
Holding power of boiler tubes, 111.
Of diameter of rivets and thickness of plate, 113.
Of safe internal pressure, 118-120.
Of defects found in steam boilers, 125.
Showing loss at different thicknesses by corrosion, 143.
Showing sediment collecting in boilers, 163.
Showing rise of safety valve, 195.
Of savings from use of feed water, 200.
Capacity of cisterns, 202,
Of specific heat, 214.
Of conducting power of various substances, 213.
Of radiating power of various substances, 213.
Weight of cubic foot of water, 224.
Weight and capacity of gallons of water, 225.
Comparative quantity of water which can be evaporated, 231.
Surfaces and capacities of pipes, 246.
Of data relating to pipes, 247.
Bursting pressure of tubes, 264.
Of weights of round and plate iron, 309, 311.
Conducting power of various substances, 275.
Relative value of non-conductors, 276.
Weights of lead pipe, 305.
=Tan=, description, 15.
=Tan bark=, comparative evaporation, 18.
Firing with, 36.
=Tanks=, for fuel oil, how to construct, 290.
=Tan-liquor=, unsafe use of, in boilers, 185.
=Tap-borer=, plumber’s, 306.
=Taps and dies=, description, 269.
=Tee=, description, 274.
=Temperature= of a furnace, 42.
=Tensile strength= of steel plate, 90.
Of boilers, 121.
=Test=, the hydraulic, 131.
=Testing-boiler=, specification, 87.
=Testing boilers= under steam pressure, 287.
=Test pieces=, description and illustration, 105, 112.
=Tests= for impurities in water, 153.
=Tests of steel rivets=, 95.
=Thimbles=, specification for, 86.
=Three way cock=, description, 273.
=Throttle valve=, description, 273.
=Tin=, melting point, 42.
Conducting power of, 213.
Specific heat of, 214.
Radiating power of, 213.
=Tissue paper=, radiating power of, 213.
=Tongs= for boiler makers, 281.
=Tool box=, description, 22.
=Tools=, plumber’s, description, 306-309.
Handy for the fire-room, 21.
Used in steam fitting, 269.
Boiler maker’s, 281.
Plumber’s caulking, 308.
=Torch=, 307.
=Total heat= of steam, 283.
=Tough=, definition, 121.
=Trained= or untrained firemen, difference, 24.
=Trap=, fish, 205.
=Treble riveting=, example, 93.
=Triple draught=, tubular boiler, 82.
=Trevithick, Richard=, frontispiece.
=Tube expanders=, 281.
=Tubes=, how to weld, 264.
Table of bursting and collapsing pressures, 264.
Boiler, illustration of size, 245.
Experiments in holding power, 111.
Table of holding power, 111.
Boiler, table of dimensions, 110.
Leaky, how to repair, 126.
=Tubes and flues=, sweeping, 39.
=Tube sheets=, description, 81.
=Turn-pin=, description, 306.
=Two flue= steam boiler, 78.
=Umbria=, steamer, firing boilers, 32.
=Unequal riveting=, example, 93.
=Union=, description, 274.
=Unit= of chimney measurements, 297.
=Upright steam boilers=, description, 51.
=Uptakes= of marine boiler, 64.
=Valve=, gate, 273.
Globe, description, 272.
Brine, description, 273.
Pop, description, 184.
Angle, description, 273.
Check, description, 278.
Sentinel, description, 184.
Pressure regulator, 274.
Rotary, description, 273.
Straightway, description, 273.
Throttle, description, 273.
Ball, description, 273.
Chamber, description, 272.
Double beat and double seat, 273.
Swing description, 273.
=Valve bracket=, description, 272.
=Valve cock=, description, 272.
=Valve coupling=, description, 272.
=Valves=, description, 271.
Safety, description, 187.
Of what material made, 274.
=Valves=, hinged, description, 272.
Relief, description, 272.
Back pressure, description, 273.
Lifting, description, 274.
=Valves and cocks=, description, 272.
=Valve-seat=, description, 272.
=Vaults= for fuel oil, how to construct, 289.
=Ventilation=, 265.
=Vise=, steamfitter’s, 269.
=Vises=, use of, 21.
=Water=, how formed, 143.
Principles relating to, 223.
Principal temperatures of, 224.
Point of maximum density, 224.
The boiling point, 224.
The standard temperature, 224.
pecific heat of, 214.
Boiling point of pure, 37.
Radiating power of, 213.
Conducting power of, 213.
Freezing point, 224.
=Water=, (sea,) precipitator for, 145.
Boiling point of salt, 37.
=Water bending= of lead pipe, 304.
=Water circulation=, 294.
=Water grate bars=, description, 175.
Gauge cocks, description, 176.
=Water hammer=, 283.
=Water meters=, rule for reading, 205.
Description, 203.
=Water ram=, 284.
=Water space= of boilers, rule and example, 105.
=Water table= in locomotive, 35.
=Water tube= steam boiler, description, 67.
=Water heater=, noiseless, 312.
=Water tube steam boiler=, setting of, 239.
=Watt, James=, 68.
=Weight= of different standard gallons of water, 225.
Of a column of air, 17.
=Weldable=, definition, 121.
=Welding= boiler and other tubes, 264.
=Wet steam=, 283.
=Wheelbarrow=, use of, 20.
=Whistle=, steam, description, 180.
=Whitewash=, description, 232.
=Wipe joint=, how to make, 300.
Plumber’s, 298.
=Wood=, comparative evaporation, 18.
Specific heat of, 214.
As a combustible, 14.
“Hint as to drying,” 14.
=Wood charcoal=, comparative evaporation, 18.
=Wood chisel=, 307.
=Wounds=, treatment of, 310.
=Writing paper=, radiating power of, 213.
=Zig-zag riveting=, example, 93.
=Zinc=, conducting power of, 213.
Melting point, 42.
Effect on corrosion of boilers, 150.
Use in marine boilers, 162.
Specific heat of, 214.
[Illustration: Page decoration oil cans]
MECHANICAL LIST
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Planing; Milling; Drilling; Grinding; Punching and Shearing.
=Lathe Work=.—Forms and use of Foot Lathes; Hand Lathes; Chuck or
Surfacing Lathe; Engine Lathe; Parts of the Lathe; Cutting Tools Used
in the Lathe; Tempering of Lathe Tools Rule; Lathe Practice; Measuring
Instruments; Mandrels; Lathe-Dogs; Driving Work Between Centers;
Turning Work Between Centers; Lathe Speed; Chuck and Face-plate Work;
Drilling and Boring in the Lathe; Proportion of Parts of a Lathe;
Useful References; Tables and Index.
[Illustration: RODGER’S PROGRESSIVE MACHINIST
AUDEL]
=Description of Binding=.—The book is handsomely bound in black
cloth, with gold edges and titles, printed on fine paper, illustrated
with 330 diagrams and drawings of practical work, containing over 360
pages of valuable information, and 1081 ready reference index for quick
information. =+This volume will be mailed to any address postpaid upon
receipt of 2 dollars.+=
AUDELS GAS ENGINE MANUAL $2
[Illustration: AUDELS GAS ENGINE MANUAL
A PRACTICAL TREATISE WITH ILLUSTRATIONS AND DIAGRAMS
T A Co.]
THIS volume just published gives the latest and most helpful
information respecting the construction, care and management of =+Gas,
Gasoline and Oil Engines, Marine Motors+= and =+Automobile Engines+=,
including chapters on =+Producer Gas Plants+= and the =+Alcohol Motor+=.
The work is divided into 27 Chapters as follows:—Historical
Development—Laws of Permanent Gases—Theoretical Working
Principles—Actual Working Cycles—Graphics of the Action of
Gases—Indicator Diagrams of Engine Cycles—Indicator Diagrams of Gas
Engines—Fuels and Explosive Mixtures—Gas Producer Systems—Compression,
Ignition and Combustion—Design and Construction—Governing and
Governors—Ignition and Igniters—Installation and Operation—Four-Cycle
Horizontal Engines—Four-Cycle Vertical Engines—Four-Cycle Double-Acting
Engines—Two-Cycle Engines—Foreign Engines—Oil Engines—Marine
Engines—Testing—Instruments Used in Testing—Nature and Use of
Lubricants—Hints on Management and Suggestions for Emergencies—The
Automobile Motor—Useful Rules and Tables.
Each chapter is illustrated by diagrams which make it a thoroughly
helpful volume, containing 512 pages, 156 drawings, printed in large
clear type on fine paper, handsomely bound in rich red cloth, with gold
top and title, measuring 5-1/2 × 8-1/2 inches and weighing over two
pounds.
The book is a practical educator from cover to cover and is worth many
times the price to any one using a gas engine of any type or size.
PRICE $2.00 POSTPAID.
THEO. AUDEL & CO., 63 FIFTH AVENUE, NEW YORK, N. Y.
MOTOR CAR PRACTICE $2
A Good Book for Owners, Operators, Repairmen and Intending Purchasers.
[Illustration: AUTOMOBILES
SELF PROPELLED VEHICLES
J.E.HOMANS
A PRACTICAL TREATISE WITH ILLUSTRATIONS AND DIAGRAMS
5ᵗʰ EDITION REVISED
]
THIS work is now the accepted standard on the practical care and
management of motor cars—explaining the principles of construction and
operation in a clear and helpful way, and fully illustrated with many
diagrams and drawings, making it of value to the intending purchaser,
driver and repair man.
The subjects treat of the needs of the man behind the wheel, and are
presented clearly, concisely and in a manner easy to understand by the
reader, be he a beginner or an expert.
The treatise on the gasoline engine cannot fail to prove valuable to
anyone interested in explosive motors, which are daily coming to the
front as the readiest and most convenient source of power.
Contains 608 pages, over 400 diagrams and illustrations, printed on
fine paper, size 5-3/4 by 8-1/2 inches, with generously good binding.
Highly endorsed. This book will be sent to any address in the world,
postpaid, upon receipt of =$2=.
THEO. AUDEL & CO., 63 FIFTH AVENUE, NEW YORK
PUMPS AND HYDRAULICS $4
2 PARTS
IT is with pleasure we call your attention to the recent publication on
pumping machinery. This work, issued under the title of “ROGERS’ PUMPS
AND HYDRAULICS,” is a complete and practical handbook, treating on the
construction, operation, care and management of pumping machinery;
the principles of hydraulics being also thoroughly explained. The
work is illustrated with cuts, diagrams and drawings of work actually
constructed and in operation; the rules and explanations of the
examples shown are taken from everyday practice. No expense has been
spared in the endeavor to make this a most helpful instructor on the
subject, useful to all pump attendants, engineers, machinists and
superintendents.
[Illustration:
PUMPS AND HYDRAULICS
ROGERS
A PRACTICAL TREATISE WITH ILLUSTRATIONS AND DIAGRAMS
PART ONE
T A Co.
PUMPS AND HYDRAULICS
ROGERS
A PRACTICAL TREATISE WITH ILLUSTRATIONS AND DIAGRAMS
PART TWO
T A Co.
]
Subjects Treated
The Air Pump; Air and Vacuum Pumps; Air Compressors; The Air Lift Pump;
The Steam Fire Engine; Miscellaneous Pumps; Mining Pumps; Marine Pumps;
“Sugar-house” Pumps; Circulating Pumps; Atmospheric Pumps; Ammonia or
Acid Pumps; The Screw Pump; Aermotor Pumps; Rotary and Centrifugal
Pumps; Turbine Pumps; Injectors and Ejectors; Pulsometer-Aqua-Thruster;
Pump Speed Governors; Condensing Apparatus; Utilities and Attachments,
Tools, Valves and Piping, Pipes, Joints and Fittings, Useful Notes;
Tables and Data; Glossary of Pump and Hydraulic Terms; Elementary
Hydraulics; Flow of water Under Pressure; Water Pressure Machines,
Water Wheels; Turbine Water Wheels; Turbine Pumps; Water Pressure
Engines; Hydraulic Motors; Hydraulic Apparatus; Hydraulic Jack;
Hydraulic Press; Hydraulic Accumulator; Hydraulic Ram; Pumps as
Hydraulic Apparatus; Classification of Pumps; Hand Pumps; Power Pumps;
Belted Pumps; The Electric Pump; The Steam Pump; The Duplex Pump;
Underwriter Fire Pump; Specifications of the National Board of Fire
Underwriters Relating to Duplex Fire Pumps.
These two volumes of nearly nine hundred pages, illustrated with
about seven hundred wood cuts, are admirable specimens of bookmaking;
they are printed on fine white paper in large clear text, with ample
margins, and bound in black vellum cloth with titles and tops in gold.
In size they are six by nine inches.
——PRICE, $4, DELIVERED——
MARINE ENGINEERING $2
[Illustration:
QUESTIONS AND ANSWERS FOR MARINE ENGINEERS
LUCAS
HAWKINS
PRICE $2.
AUDEL & CO
WITH CHAPTER ON =+BREAKDOWNS AT SEA+=
]
THIS treatise is the most complete published for the practical
engineer, covering as it does a course in mathematics, the management
of marine engines, boilers, pumps, and all auxiliary apparatus, =+the
accepted rules for figuring the safety-valve+=.
The book is divided into two parts: Part I, Construction: Part II,
Operation; it contains 700 pages.
The volume is illustrated with plate drawings, diagrams and cuts,
having an Index with more than =+1,000 ready references, 807 Questions
on practical marine engineering are fully answered and explained+=.
Size is 5-3/4 × 8-1/2 inches, 1-1/2 inches thick, and weighs nearly
three pounds, strongly and durably bound in rich green cloth, with full
gilt edges, and is the accepted standard on Marine Engineering.
Price =$2=, sent free to any address in the world.
=+Money will be refunded if not entirely satisfactory.+=
THEO. AUDEL & CO., 63 FIFTH AVENUE, NEW YORK
MECHANICAL DRAWING $2
THE work has been carefully arranged according to the fundamental
principles of the art of drawing, each theme being clearly illustrated.
=+A list of the subjects are given below:+=
[Illustration: HAWKINS MECHANICAL DRAWING
HAWKINS SELF HELP MECHANICAL DRAWING FOR HOME STUDY
]
Chalk Work; Preliminary Terms and Definitions; Freehand Drawing;
Geometrical Drawing; Drawing Materials and Instruments; Mechanical
Drawing; Penciling; Projection; “Inking in” Drawings; Lettering
Drawings; Dimensioning Drawings; Shading Drawings.
Section Lining and Colors; Reproducing Drawings; Drawing Office Rules;
Gearing; Designing Gears; Working Drawings; Reading Working Drawings;
Patent Office Rules for Drawings; Useful Hints and Points; Linear
Perspective; Useful Tables; Personal, by the Editor.
The book contains 320 pages and 300 illustrations, consisting largely
of diagrams and suggestive drawings for practice. It is bound in dark
green cloth with full gold edges and titles; it is printed on fine
paper, size 7 × 10 inches; it weighs 33 oz., and will fit into any
engineer’s or mechanic’s library to good advantage.
PRICE, $2, Postpaid.
THEO. AUDEL & CO., 63 FIFTH AVENUE, NEW YORK
ELECTRICITY FOR ENGINEERS $2
THE introduction of electrical machinery in almost every
power plant has created a great demand for competent
engineers and others having a knowledge of electricity
and capable of operating or supervising the running of electrical
machinery. To such persons this pocket-book will be
found a great benefactor, since it contains just the information
that is required, _explained in a practical manner_.
[Illustration:
HAWKINS’ NEW CATECHISM OF ELECTRICITY.
HAWKINS’]
=+Plan of Study+=
The following is a partial list of the topics discussed and illustrated:
Conductors and Non-Conductors: Symbols, abbreviations and definitions
relating to electricity; The Motor; The Care and Management of the
Dynamo and Motor.
Electric Lighting; Wiring; The rules and requirements
of the National Board of Underwriters in full; Electrical Measurements.
The Electric Railway; Line Work; Instruction and Cautions for Linemen
and the Dynamo Room; Storage Batteries; Care and Management of the
Street-Car Motor; Electro Plating.
The Telephone and Telegraph; The Electric Elevator; Accidents and
Emergencies, etc., etc.
One-third of the whole book has been devoted to the explanation and
illustrations of the dynamo, and particular directions relating to its
care and management;—all directions being given in the simplest and
kindly way to assist rather than confuse the learner.
It contains 550 pages with 300 illustrations of electrical appliances;
it is bound in heavy red leather, (size 4-1/2 × 6-1/2 for the pocket),
with full gold edges and is a most attractive handbook for Electricians
and Engineers.
PRICE, $2, Postpaid.
THEO. AUDEL & CO., 63 FIFTH AVENUE, NEW YORK
ENGINEERS’ EXAMINATIONS $2
THIS work is an important aid to engineers of all grades, and is
undoubtedly the most helpful ever issued relating to a safe and sure
preparation for examination. It presents in a condensed form the most
approved practice in the care and management of Steam Boilers, Engines,
Pumps, Electrical and Refrigerating Machines, also a few plain rules of
arithmetic with examples of how to work the problems relating to the
safety valve, strength of boilers and horse power of the Steam Engine
and Steam Boiler.
It contains various rules, regulations and laws of large cities for
the examination of boilers and the licensing of engineers. It contains
the laws and regulations of the United States for the examination and
grading of all marine engineers.
The book gives the underlying principles of steam engineering in plain
language, with very many sample questions and answers likely to be
asked by the examiner.
It also gives a short chapter on the “Key to Success” in obtaining
knowledge necessary for advancement in engineering.
[Illustration:
_HAWKIN’S AIDS._
ENGINEERS’ EXAMINATIONS
—WITH—
QUESTIONS AND ANSWERS
]
This helpful volume contains 200 pages of valuable information not
elsewhere obtainable; it is bound in rich red leather with full gold
edges and titles; it measures 5 × 7-1/2 inches and weighs twenty-two
ounces.
PRICE, $2, Postpaid.
THEO. AUDEL & CO., 63 FIFTH AVENUE, NEW YORK
STEAM BOILER PRACTICE $2
THIS book of instruction on boiler-room practice will be of great help
to firemen, engineers and all others who wish to learn about this
important branch of Steam Engineering.
It treats on materials, coals, wood, coke, and oil and gas, fuels,
etc., their composition, properties, combustive value, also on
combustion and evaporation.
Giving the practical rules to be observed in firing with various fuels,
management of steam boilers, prevention of foaming; tools and fire
irons; covering stationary, marine and locomotive boilers.
It enumerates sixty important points of cautions to be observed in the
proper management of boilers.
It contains a description of and full treatise on stationary, marine
and locomotive boilers, and the historical development of boilers;
specifications for boilers; riveting; bracing; rules for finding
pressure or strain on bolts.
It gives inspectors rules relating to braces in steam boilers. Also
rules and tables for calculating areas and steam and water space of
boilers.
It treats on boiler tubes, construction and drawing of boiler sections;
defects and necessary repairs; inspection of steam boilers; mechanical
stokers’ corrosion and scale, boiler compounds, feed water heaters,
injectors, pumps, boiler settings; pipes and piping; steam heating,
chemistry of the furnace; boiler making; plumbing, and hundreds of
other useful subjects.
It states several plain rules for the calculation of safety valve
problems and those sanctioned by the U. S. inspectors.
[Illustration:
MAXIMS AND INSTRUCTIONS FOR THE BOILER ROOM
N. HAWKINS ME
AUDEL & CO.
]
The volume has 330 pages and 185 illustrations and diagrams. It is 6
× 8-1/2 in. in size and weighs 28 ounces. The binding is uniform with
that of the “Calculations” and “Catechism of the Steam Engine,” being
bound in heavy green cloth, with ornamental titles and edges in gold.
PRICE, $2, Postpaid.
THEO. AUDEL & CO., 63 FIFTH AVENUE, NEW YORK
CALCULATIONS FOR ENGINEERS $2
THE Hand Book of Calculations is a work of instruction and reference
relating to the steam engine, the steam boiler, etc., and has been said
to contain every calculation, rule and table necessary to be known by
the Engineer, Fireman and a steam user.
Giving a complete course in Mathematics for the Engineer and steam
user; all calculations are in plain arithmetical figures, so that the
average man need not be confused by the insertion of the terms, symbols
and characters to be found in works of so-called “higher mathematics.”
Mechanical Powers; Natural or Mechanical Philosophy; Strength of
Materials; Mensuration; Arithmetic; Description of Algebra and Geometry.
Tables of Weights, Measures, Strength of Rope and Chains, Pressures
of Water, Diameter of Pipes, etc.; The Indicator, How to Compute; The
Safety Valve, How to Figure; The Steam Boiler; The Steam Pump; Horse
Powers, How to Figure for Engines and Boilers; Steam, What It Is, etc.
Index and Useful Definitions.
[Illustration:
HAND BOOK OF CALCULATION FOR ENGINEERS
H. HAWKINS ME
AUDEL & CO.
]
This work contains 330 pages and 150 illustrations; it is durably and
handsomely bound, uniform in style and size with the “Instructions for
the Boiler Room” and the “Catechism of the Steam Engine;” it has gold
edges and titles, and weighs over 28 ounces.
PRICE, $2, Postpaid.
THEO. AUDEL & CO., 63 FIFTH AVENUE, NEW YORK
STEAM ENGINE PRACTICE $2
“It has been well said that engineers are born, not made; those in
demand to fill the positions created by the great installations of
power-producing machinery now so common, are men who are familiar
with the contents of good books, and as well, are the product of a
hard bought practical experience.”
THIS work is gotten up to fill a long-felt need for a practical book.
It gives directions for running the various types of steam engines that
are to-day in the market.
A list of subjects, which are fully yet concisely discussed, are as
follows:
Introduction; The Steam Engine; Historical Facts Relating to the
Steam Engine: Engine Foundations; The Steam Piston; Connecting Rods;
Eccentric; Governor; Materials; Workmanship; Care and Management;
Lining up a Horizontal or Vertical Engine; Lining Shafting; Valve
Setting; Condensers; Steam Separators; Air, Gas, and Compressing
Engines: Compounding; Arithmetic of the Steam Engine; Theory of the
Steam Engine; Construction.
There also is a description of numerous types of the engines now in
operation, such as the Corliss, Westinghouse, and many others.
The book also treats generously upon the Marine, Locomotive and Gas
Engines.
[Illustration:
NEW CATECHISM OF THE STEAM ENGINE
N. HAWKINS ME
AUDEL & CO.
]
This is a rarely fine book, handsomely bound in green silk cloth, with
full gold edges and titles; it contains 440 pages, 325 illustrations;
in size it is 6 × 8-1/4 inches, and weighs 2 pounds.
PRICE, $2, Postpaid.
THEO. AUDEL & CO., 63 FIFTH AVENUE, NEW YORK
STEAM ENGINE INDICATOR $1
THE work is designed for the use of erecting and operating engineers,
superintendents, and students of steam engineering, relating, as it
does, to the economical use of steam.
The following is a general outline of the subjects defined, illustrated
and presented most helpfully in the book.
Preparing the Indicator for use; Reducing Motions; Piping up Indicator;
Taking Indicator Cards; The Diagram; Figuring Steam consumption by the
diagram; Revolution Counters; Examples of Diagrams; Description of
Indicators; Measuring Diagram by Ordinates; Planimeters; Pantagraphs,
Tables, etc.
He who studies this work thoughtfully will reap great benefit and
will find that there is nothing difficult or mysterious about the use
of the Steam Engine Indicator. This knowledge is necessary to every
well-informed engineer and will undoubtedly be highly appreciated and a
stepping-stone toward promotion and better things.
[Illustration:
PRACTICAL TREATISE
—ON THE—
STEAM ENGINE INDICATOR
HAWKINS INDICATOR.
]
The work is fully illustrated, handsomely bound, and is in every way a
high grade publication.
----PRICE, $1.00----
THEO. AUDEL & CO., 63 FIFTH AVENUE, NEW YORK
TELEPHONE ENGINEERING $1
THE “A B C of the Telephone” is a book valuable to all persons
interested in this ever-increasing industry. No expense has been spared
by the publishers, or pains by the author, in making this the most
comprehensive handbook ever brought out relating to the telephone.
TABLE OF CONTENTS
=+29 CHAPTERS+=
The Telephone Apparatus and its Operation; A Brief Survey of the
Theory of Sound, Necessary to an Understanding of the Telephone; A
Brief Survey of the Principles of Electricity; Electrical Quantities;
History of the Speaking Telephone; Later Modifications of the Magnet
Telephone; The Carbon Microphone Transmitter; The Circuits of a
Telephone Apparatus; The Switch Hook and its Function in Telephone
Apparatus; The Switchboard and the Appliances of the Central Station;
The Operator’s Switch Keys and Telephone Set; Improved Switchboard
Attachments; Switchboard Lamp Signals and Circuits; The Multiple
Switchboard; Locally Interconnected or Multiple Transfer Switchboard;
Exchange Battery Systems; Party Lines and Selective Signals; Private
Telephone Lines and Intercommunicating Systems; Common Return Circuits;
Private Telephone Lines and Intercommunicating Systems; Full Metallic
Circuits; Large Private Systems and Automatic Exchanges; Devices for
Protecting Telephone Apparatus from Electrical Disturbances; The
General Conditions of Telephone Line Construction; Telephone Pole
Lines; Wire Transportations on a Pole Line. Telephone Cables and their
Use in Underground and Pole Lines; Circuit Balancing Devices; The
Microtelephone; Wireless Telephony; Useful Definitions and Hints on
Telephone Management.
=+WITH READY REFERENCE INDEX+=
[Illustration:
HOYMAN’S A·B·C OF THE TELEPHONE
A PRACTICAL TREATISE WITH ILLUSTRATIONS AND DIAGRAMS
$1
AUDEL & CO.
NEW YORK
]
The volume contains 375 pages, 268 illustrations and diagrams; it is
handsomely bound in black vellum cloth, and is a generously good book
without reference to cost.
PRICE, $1, Postpaid.
THEO. AUDEL & CO., 63 FIFTH AVENUE, NEW YORK
Hawkins’ Dictionary,_$3.50_
=+THIS volume is the most useful book in Mechanical Literature.+=
If constantly referred to will enable the student to acquire a correct
knowledge of the words, terms and phrases in use in Mechanical
Engineering and its various branches.
=+Its greatest value lies in this:+= that no man representing the
mechanical profession can find excuse for not knowing the use and
meaning of the terms used in his work.
=+HAWKINS’ MECHANICAL DICTIONARY+= explains and defines in plain
language the use of all words and terms now used or heretofore used in
the =+Mechanic Arts, Trades and Sciences+=.
=+It is an unequaled reference work+=, and is the one book of permanent
value no student or expert should dispense with. Complete from A to Z.
Highly endorsed.
[Illustration:
HAWKINS’ MECHANICAL DICTIONARY
A CYCLOPEDIA OF WORDS, DATA AND PHRASES
]
Contains 704 pages, handsomely bound, price $3.50 postpaid.
Satisfaction guaranteed.
* * * * * *
Transcriber’s note:
The original spelling, hyphenation, accentuation and punctuation has
been retained, except for apparent typographical errors.
A table of contents has been added by the transcriber following the
preface.
Index entry ‘Evans, Robt., 11.’ corrected to read ‘Evans, Oliver, viii.’
In the chapter ‘CHIMNEYS AND DRAUGHT’ 12th para:-
‘… having about 1 square foot of heating surface to 45 square feet of
heating surface.’
This has been changed to read:-
‘… having about 1 square foot of grate area to 45 square feet of
heating surface.’
The references to a ‘Six Inch Flue Boiler’ in Fig. 32 and the Index may
mean ‘Six Flue Boiler’, these instances have not been changed.
In the chapter ‘CHEMISTRY OF THE FURNACE’, the opening paragraph
has a number of apparent typographical errors relating to names of
substances. These have been left as printed and are:-
naphthaline typographical error for naphthalene
alizarine „ „ „ alizarin
toludine „ „ „ toluidine
anthracine „ „ „ anthracene
toluches „ „ „ toluene
saccharine „ „ „ saccharin
*** End of this LibraryBlog Digital Book "Maxims and Instructions for the Boiler Room - Useful to Engineers, Firemen & Mechanics; Relating to Steam Generators, Pumps, Appliances, Steam Heating, Practical Plumbing, etc." ***
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