_The fire engine is essentially an apparatus adapted to emergencies_,
and owing to the intermittent nature of the duty performed, it is
quite likely, unless the proper precautions are observed, that its
several parts, more especially its interior mechanism, will suffer more
deterioration while standing idle than from actual service.
It is necessary that these interior parts, as well as those more
readily apparent, be cared for with a view of keeping them constantly
in condition to endure the most severe and protracted strains at
the shortest notice. While standing in the house, the engine should
at all times be kept ready for immediate service, with shavings and
kindlings in the fire-box, and as much kindlings and coal in the fuel
pan as can be conveniently carried.
In winter, if no heater is attached to the engine, the room must be
kept warm, to insure against frost.
The machine should be started gradually, but before doing so the
engineer ought to satisfy himself that the joints and connections in
the suction hose are air tight, that the discharge gate is open, the
churn valve closed, that the fire has been properly attended to, the
cylinder cocks open, the exhaust nearly closed, and all the bearings
and journals well oiled, and the wheels properly blocked, especially
if the engine is standing on a grade.
The automatic air cocks on the upper pump heads must be opened
immediately after starting. They serve to promptly relieve the upper
pump discharge chambers of air, and may be closed as soon as water
escapes from their orifices.
When cylinder condensation has nearly ceased, the engine being warm,
the drain cocks should be closed and the machine speeded up gradually
until a good pressure of steam is obtained.
Until the engineer has had some experience with the machine, and is
familiar with its workings, it is not advisable to use more than 90
or 100 pounds of steam, which is all that is required for ordinary
fire duty; the necessity for more than 120 pounds will probably never
arise.
The stuffing-boxes of the engine and pump should be carefully packed.
All of the bearings and journals, as well as the oil cans, should
be well supplied with good oil. The best mineral engine oil is
recommended for this purpose, as it does not gum or change its
viscosity with variations in the temperature of the atmosphere, and
it will endure a higher temperature than animal or fish oil without
injury.
[Illustration: FIG. 430.—See page 141.]
The engineer should keep all joints tight, the stuffing-boxes
properly packed, and all bearings thoroughly oiled.
If the journal boxes or other working parts require taking up,
remember that a little play is preferable to a close adjustment
liable to cripple the engine at a critical moment. To insure perfect
safety, always thoroughly test the apparatus after making such
repairs, by subjecting the parts affected, to the strains usually
encountered in actual service.
The principal requirement of the steam cylinders and slide valves is
proper and constant lubrication. Let this one item be attended to,
and its mechanism will practically take care of itself for many years.
The joints and connections in the suction must be perfectly tight.
Before laying the fire, see that the grate and fire-box are clean,
also that the grate bars are fast, so they will not be liable to jar
out, and that all the steam outlets of the boiler are tightly closed.
Lay on the grate some dry pine shavings—not too many—spread evenly
over the grate, with a few hanging down between the bars; on the
shavings put some finely-split pine or hemlock wood, then some a
little coarser, and finally a quantity coarser still. It is well to
put on the top some finely-split hard wood. These kindlings must all
be dry and split—not sawed—and should be put in loosely, in layers,
the layers being crossed, so that there will be a free circulation of
air between them.
To light the fire: Apply torch (described in page 135) _below the
grate_, never in the door; and while doing so move the torch around
to insure thoroughly igniting the shavings.
When there is a pressure of 40 to 60 pounds of steam, begin throwing
in coal, a little at a time, broken up in pieces about the size
of a man’s fist. Bituminous coal should be used, the same as that
from which illuminating gas is made. It should be of the very best
quality, and very free burning.
Do not put the wood or coal all close to the fire door, but scatter
it about and spread it evenly over the grate.
As soon as the engine is started, coal should be put on often, a
little at a time, and the grate should be kept covered, but not
thickly—say to a depth of three or four inches. Be particular to fire
evenly and regularly, _taking care to cover air holes through the
fire_, and to keep the fire door closed as much as possible.
The grate bars should be kept well raked out from below, and the fire
and coal occasionally stirred off the grate bars inside the fire-box,
using the flat side of the poker for the latter operation.
[Illustration: FIG. 431.—See page 138.]
[Illustration: FIG. 432.—See page 138.]
[Illustration: FIG. 433.—See page 139.]
The water in the boiler should be carried as high as six or eight
inches in the glass tube as soon as the engine gets fairly to work
and a good pressure of steam is raised. The gauges will indicate more
water in the boiler when the machine is running than it will with the
same quantity of water if it is not at work, owing to the expansion
of water by the application of heat.
If there is a tendency to foam, the feed should be increased and the
surface blow-off opened quite frequently to relieve the boiler of the
scum and surplus water. If the foaming is unusually violent, it may
be subdued by stopping the engine for a few moments and permitting
the water to settle.
During temporary stops the fire should be cleaned, by removing the
clinkers and the moving parts of the machinery examined and oiled.
The boiler is usually fed by force pumps, the plungers of which are
secured directly to the yokes of the main engines. Both pumps are
arranged to work in unison; and the supply is generally taken from
the discharging chamber of the main pumps, and is controlled by an
ordinary globe valve. Should the water being delivered by the main
pumps be unsuitable for feeding the boiler, this valve must remain
closed, and a supply from a barrel or tank introduced through the
connection provided for that purpose.
When feeding the boiler, it is a good plan to occasionally feel the
pipe leading from check to boiler with the hand, as one can tell
by this means whether the pump is feeding properly. If feeding all
right, the pipe will be cool. If the pipe is hot, the pump is not
feeding properly, try the pet cock.
Always keep a good torch, ready for use, in the fuel pan. This can be
made by tying some cotton waste on one end of a stick about two feet
long and saturating the waste with kerosene oil.
The kindling should be carefully prepared, and the quantity carried
sufficient to generate a working pressure in the boiler before coal
is added to the fire.
Care should be taken not to use too large nozzles if two or more
streams are being thrown.
Owing to the contracted diameter of fire hose, the flow of the water
is retarded; the loss of power due to friction increases directly
with the length of the line and nearly as the square of velocity. In
other words, if the loss due to a given flow be 12 pounds for 100
feet of hose, then 24 pounds will be required to maintain the same
rate through an additional 100 feet. To double the velocity will
require four times the pressure, or 48 pounds for 100 feet and 96
pounds for 200 feet.
From this brief explanation, it must be plain that the capacity
of any engine is diminished as the length of the line of hose is
increased.
For this reason, the greater the lift the smaller the stream that
can be thrown effectively, and the size of nozzle used should depend
upon the height the water is draughted, reducing it one-eighth inch
for every five feet above a lift of ten feet. If the engine uses a
1-1/4-inch nozzle for ordinary work, it will answer for any lift up
to 10 feet. If water has to be draughted 15 feet, a 1-1/8-inch nozzle
should be used; if 20 feet, 1-inch; and if 25 feet, 7/8-inch.
Never start a fire unless one full gauge cock of water appears in the
boiler.
The suction basket or strainer should always be attached when
draughting water, and every precaution taken _to insure tight
connections in the suction_. The basket must be kept well under the
surface, to avoid clogging if the water be foul.
When the supply is taken from a hydrant, the valve should be fully
turned on; if opened before water is wanted through the hose the
discharge gates on the pumps must be closed. Unless the pressure is
excessive, the hydrant is usually permitted to remain open while
the steamer is attached, the discharge during temporary stops being
controlled by the pump gates.
_The apparatus should always be halted, or placed at a proper point,
with reference to the source of the water supply._ When attached to
a hydrant or plug, do not run the engine faster than the water will
flow to supply the pump, and if the supply is not sufficient to allow
the pump to work to its full capacity, avoid using too large nozzles.
The safety of life and property is very often dependent upon the
skill and good judgment of the engineer, and as the maximum effect
of such apparatus is generally required at the most critical time
and under the most exciting circumstances, it is important that
the endeavor by constant and persistent practice to acquire that
confidence and proficiency that will insure a correct and decisive
action in all matters pertaining to the management of the machine.
From three-fourths to one inch of water should be indicated in the
glass gauge, except when there is a heater attached to the engine,
then from four to five inches should be carried. The bottom of the
glass tube being on a line with the crown-sheet, when one inch of
water shows in the tube, the water-line in the boiler is then one
inch above the crown-sheet.
It is advisable occasionally—say once a month—in towns where fires
are not frequent, to fire up and take the engine out for practice and
drill, and to make sure that it is in proper working order, after
which the boiler should be blown off and refilled with fresh water,
as hereinafter directed.
Every engine required to pump salt water, or other water unfit for
the boiler supply, should be provided with a fresh-water feed tank.
_The purpose of the automatic air cock_ (if there is one) is to
prevent the rattling of the check valves when the pumps are being
only partially filled; if the supply is to be drawn from a barrel or
tank, the entrance of air through this cock must be prevented.
_When draughting the water, bear in mind that the greater the
perpendicular lift the less the quantity of water which can be
pumped_, remembering that it is the pressure of the atmosphere which
forces the water into the pump, and not any power exerted by the
pump itself, which simply produces the vacuum. Thus, the nearer the
surface of the water the greater the velocity with which it enters
the pump, while the higher the pump the weaker the pressure and the
less the quantity of water which enters it, and at a height of about
30 feet no water at all will go into the pump.
If it is suspected that one of the joints in the suction is loose,
the speed of the engine may be slackened without stopping entirely,
until water is thrown eight or ten feet from the nozzle, when if the
pump is taking air the stream will snap and crack instead of flowing
out smoothly. If it is found that the pump is taking air through
the suction, and the leak cannot be located in any other way, it
may be found by removing the suction basket and turning the end of
the suction up higher than the top of the pump, and then filling it
with water. The water will be forced out through the joints wherever
loose, and leaks can be found in this way.
The principal object of _the churn valve_ is to permit the operation
of the pumps without discharging any water through the natural
channels; it controls a passage by which the discharging side of the
pumps is connected with the suction chamber. In draughting water,
when the pumps are first started, _this valve must remain closed_
until the pumps are filled with water, thereby excluding the air
which would find its way into the suction chamber if the same were
open. It should also be closed when the pumps are at rest, to prevent
the dropping of the water into the suction pipe.
When the engine is put to suction, acquire the habit of feeling this
valve to assure its complete closure.
If there is anything about the engine that is not fully understood,
or if it fails to do its work properly from any cause, the maker
should be communicated with at once; inquiries are promptly answered,
and usually required information or suggestions are cheerfully
furnished.