POINTS FOR THE YOUNG ENGINEER.
QUESTIONS AND ANSWERS.
THE BOILER.
Q. How should water be fed to a boiler?
A. In a steady stream, by use of a pump or injector working
continuously and supplying just the amount of water required. By this
means the water in the boiler is maintained at a uniform level, and
produces steam most evenly and perfectly.
Q. Why should pure water be used in a boiler?
A. Because impure water, or hard water, forms scales on the boiler
flues and plates, and these scales act as non-conductors of heat. Thus
the heat of the furnace is not able to pass easily through the boiler
flues and plates to the water, and your boiler becomes what is called
“a hard steamer.”
Q. What must be done to prevent the formation of scale?
A. First, use some compound that will either prevent scale from
forming, or will precipitate the scale forming substance as a soft
powder that can easily be washed off. Sal soda dissolved in the feed
water is recommended, but great care should be exercised in the use of
sal soda not to use too much at a time, as it may cause a boiler to
foam. Besides using a compound, clean your boiler often and regularly
with a hand hose and a force pump, and soak it out as often as possible
by using rain water for a day or two, especially before cleaning. Rain
water will soften and bring down the hard scale far better than any
compound.
Q. How often should you clean your boiler?
A. As often as it needs it, which will depend upon the work you do and
the condition of the water. Once a week is usually often enough if the
boiler is blown down a little every day. If your water is fairly good,
once a month will be often enough. A boiler should be blown off about
one gauge at a time two or three times a day with the blow-off if the
water is muddy.
Q. How long should the surface blow-off be left open?
A. Only for a few seconds, and seldom longer than a minute. The surface
blow-off carries off the scum that forms on the water, and other
impurities that rise with the scum.
Q. How do you clean a boiler by blowing off?
A. When the pressure has been allowed to run down open the blow-off
valve at the bottom of the boiler and let the water blow out less than
a minute, till the water drops out of sight in the water gauges, or
about two and one-half inches. Blowing off more is only a waste of heat
and fuel.
Q. What harm will be done by blowing off a boiler under a high pressure
of steam?
A. The heat in the boiler while there is such a pressure will be so
great that it will bake the scale on the inside of the boiler, and it
will be very difficult to remove it afterward. After a boiler has been
blown off the scale should be for the most part soft, so that it can be
washed out by a hose and force pump.
Q. Why should a hot boiler never be filled with cold water?
A. Because the cold water will cause the boiler to contract more in
some places than in others, and so suddenly that the whole will be
badly strained. Leaky flues are made in this way, and the life of a
boiler greatly shortened. As a rule a boiler should be filled only when
the metal and the water put into it are about at the same temperature.
Q. After a boiler has been cleaned, how should the manhole and manhole
plates be replaced?
A. They are held in position by a bolt passing through a yoke that
straddles the hole; but to be steam and water tight they must have
packing all around the junction of the plate with the boiler. The best
packing is sheet rubber cut in the form of a ring just the right size
for the bearing surface. Hemp or cotton packing are also used, but they
should be free from all lumps and soaked in oil. Do not use any more
than is absolutely needed. Be careful, also, to see that the bearings
of the plate and boiler are clean and smooth, with all the old packing
scraped off. Candle wick saturated with red lead is next best to rubber
as packing.
Q. What are the chief duties of an engineer in care of a boiler?
A. First, to watch all gauges, fittings, and working parts, to see that
they are in order; try the gauge cocks to make sure the water is at
the right height; try the safety valve from time to time to be sure it
is working; see that there are no leaks, that there is no rusting or
wearing of parts, or to replace parts when they do begin to show wear;
to examine the check valve frequently to make sure no water can escape
through it from the boiler; take precautions against scale and stoppage
of pipes by scale; and keep the fire going uniformly, cleanly, and in
an economical fashion.
Q. What should you do if the glass water gauge breaks?
A. Turn off the gauge cocks above and below, the lower one first so
that the hot water will not burn you. You may put in a new glass and
turn on gauge cocks at once. Turn on the lower or water cock first,
then the upper or steam cock. You may go on without the glass gauge,
however, using the gauge cocks or try cocks every few minutes to make
sure the water is at the right height, neither too high nor too low.
Q. Why is it necessary to use the gauge cocks when the glass gauge is
all right?
A. First, because you cannot otherwise be sure that the glass gauge is
all right; and, secondly, because if you do not use them frequently
they are likely to become scaled up so that you cannot use them in case
of accident to the glass gauge.
Q. If a gauge cock gets leaky, what should be done?
A. Nothing until the boiler has cooled down. Then if the leak is in the
seat, take it out and grind and refit it; if the leak is where the
cock is screwed into the boiler, tighten it up another turn and see if
that remedies the difficulty. If it does not you will probably have to
get a new gauge cock.
Q. Why not screw up a gauge cock while there is a pressure of steam on?
A. The cock might blow out and cause serious injury to yourself or some
one else. Make it a rule never to fool with any boiler fittings while
there is a pressure of steam on the boiler. It is exceedingly dangerous.
Sometimes a gauge cock gets broken off accidentally while the boiler is
in use. If such an accident happens, bank the fire by closing the draft
and covering the fire with fresh fuel or ashes. Stop the engine and let
the water blow out of the hole till only steam appears; then try to
plug the opening with a long whitewood or poplar, or even a pine stick
(six or eight feet long), one end of which you have whittled down to
about the size of the hole. When the steam has been stopped the stick
may be cut off close to the boiler and the plug driven in tight. If
necessary you may continue to use the boiler in this condition until a
new cock can be put in.
Q. What should you do when a gauge cock is stopped up?
A. Let the steam pressure go down, and then take off the front part
and run a small wire into the passage, working the wire back and forth
until all scale and sediment has been removed.
Q. What should you do when the steam gauge gets out of order.
A. If the steam gauge does not work correctly, or you suspect it does
not, you may test it by running the steam up until it blows off at
the safety valve. If the steam gauge does not indicate the pressure
at which the safety valve is set to pop off, and you have reason to
suppose the safety valve is all right, you may conclude that there is
something the matter with the steam gauge. In that case either put in
a new one, or, if you have no extra steam gauge on hand, shut down
your boiler and engine till you can get your steam gauge repaired.
Sometimes this can be done simply by adjusting the pointer, which may
have got loose, and you can test it by attaching it to another boiler
which has a steam gauge that is all right and by which you can check up
yours. It is VERY DANGEROUS to run your boiler without a steam gauge,
depending on the safety valve. Never allow the slightest variation in
correctness of the steam gauge without repairing it at once. It will
nearly always be cheaper in these days to put in a new gauge rather
than try to repair the old one.
Q. What should you do if the pump fails to work?
A. Use the injector.
Q. What should you do if there is no injector?
A. Stop the engine at once and bank the fire with damp ashes,
especially noting that the water does not fall below the bottom of the
glass gauge. Then examine the pump. First see if the plunger leaks air;
if it is all right, examine the check valves, using the little drain
cock as previously explained to test the upper ones, for the valves
may have become worn and will leak; third, if the check valves are all
right, examine the supply pipe, looking at the strainer, observing
whether suction takes place when the pump is worked, etc. There may
be a leak in the suction hose somewhere during its course where air
can get in, or it may become weak and collapse under the force of the
atmosphere, or the lining of the suction pipe may have become torn or
loose. The slightest leak in the suction pipe will spoil the working
of the pump. Old tubing should never be used, as it is sure to give
trouble. Finally, examine the delivery pipe. Close the cock or valve
next the boiler, and examine the boiler check valve; notice whether
the pipe is getting limed up. If necessary, disconnect the pipe and
clean it out with a stiff wire. If everything is all right up to this
point, you must let the boiler cool off, blow out the water, disconnect
the pipe between the check and the boiler, and thoroughly clean the
delivery pipe into the boiler. Stoppage of the delivery pipe is due to
deposits of lime from the heating of the water in the heater. Stoppage
from this source will be gradual, and you will find less and less
water going into your boiler from your pump until none flows at all.
From this you may guess the trouble.
Q. How may the communication with the water gauge always be kept free
from lime?
A. By blowing it off through the drain cock at the bottom. First close
the upper cock and blow off for a few seconds, the water passing
through the lower cock; then close the lower cock and open the upper
one, allowing the steam to blow through this and the drain cock for
a few seconds. If you do this every day or oftener you will have no
trouble.
Q. Should the water get low for any reason, what should be done?
A. Close all dampers tight so as to prevent all draft, and bank the
fire with fresh fuel or with ashes (damp ashes are the best if danger
is great). Then let the boiler cool down before putting in fresh water.
Banking the fire is better than drawing or dumping it, as either of
these make the heat greater for a moment or two, and that additional
heat might cause an explosion. Dashing cold water upon the fire is
also very dangerous and in every way unwise. Again, do not open the
safety valve, for that also, by relieving some of the pressure on the
superheated water, might cause it to burst suddenly into steam and so
cause an explosion.
Q. Under such circumstances, would you stop the engine?
A. No; for a sudden checking of the outflow of steam might bring about
an explosion. Do nothing but check the heat as quickly and effectively
as you can by banking or covering the fires.
Q. Why not turn on the feed water?
A. Because the crown sheet of the boiler has become overheated, and
any cold water coming upon it would cause an explosion. If the pump or
injector are running, of course you may let them run, and the boiler
will gradually refill as the heat decreases. Under such circumstances
low water is due to overheating the boiler.
Q. Would not the fusible plug avert any disaster from low water?
A. It might, and it might not. The top of it is liable to get coated
with lime so that the device is worthless. You should act at all times
precisely as if there were no fusible plug. If it ever does avert
an explosion you may be thankful, but averting explosions by taking
such means as we have suggested will be far better for an engineer’s
reputation.
Q. Would not the safety valve be a safeguard against explosion?
A. No; only under certain conditions. It prevents too high a pressure
for accumulating in the boiler when there is plenty of water; but when
the water gets low the safety valve may only hasten the explosion by
relieving some of the pressure and allowing superheated water to burst
suddenly into steam, thus vastly expanding instantly.
Q. Should water be allowed to stand in the boiler when it is not in use?
A. It is better to draw it off and clean the boiler, to prevent
rusting, formation of scale, hardening of sediment, etc., if boiler is
to be left for any great length of time.
Q. What should you do if a grate bar breaks or falls out?
A. You should always have a spare grate bar on hand to put in its
place; but if you have none you may fill the space by wedging in a
stick of hard wood cut the right shape to fill the opening. Cover
this wood with ashes before poking the fire over it, and it will last
for several hours before it burns out. You will find it exceedingly
difficult to keep up the fire with a big hole in the grate that will
let cold air into the furnace and allow coal to drop down.
In case the grate is of the rocker type the opening may be filled by
shaping a piece of flat iron, which can be set in without interfering
with the rocking of the grate; or the opening may be filled with wood
as before if the wood is covered well with ashes. Of course the use of
wood will prevent the grate from rocking and the poker must be used to
clean.
Q. Why should an engineer never start a boiler with a hot fire, and
never let his fire get hotter than is needed to keep up steam?
A. Both will cause the sheets to warp and the flues to become leaky,
because under high heat some parts of the boiler will expand more
rapidly than others. For a similar reason, any sudden application of
cold to a boiler, either cold water or cold air through the firebox
door, will cause quicker contraction of certain parts than other parts,
and this will ruin a boiler.
Q. How should you supply a boiler with water?
A. In a regular stream continually. Only by making the water pass
regularly and gradually through the heater will you get the full effect
of the heat from the exhaust steam. If a great deal of water is pumped
into the boiler at one time, the exhaust steam will not be sufficient
to heat it as it ought. Then if you have a full boiler and shut off the
water supply, the exhaust steam in the heater is wasted, for it can do
no work at all. Besides, it hurts the boiler to allow the temperature
to change, as it will inevitably do if water is supplied irregularly.
WHATEVER YOU DO, NEVER ATTEMPT TO TIGHTEN A SCREW OR CALK A BOILER
UNDER STEAM PRESSURE. IF ANYTHING IS LOOSE IT IS LIABLE TO BLOW OUT IN
YOUR FACE WITH DISASTROUS CONSEQUENCES.
Q. If boiler flues become leaky, can an ordinary person tighten them?
A. Yes, if the work is done carefully. See full explanation previously
given, p. 17. Great care should be taken not to expand the flues too
much, for by so doing you are likely to loosen other flues and cause
more leaks than you had in the first place. Small leaks inside a boiler
are not particularly dangerous, but they should be remedied at the
earliest possible moment, since they reduce the power of the boiler
and put out the fire. Besides, they look bad for the engineer.
Q. How should flues be cleaned?
A. Some use a steam blower; but a better way is to scrape off the metal
with one of the many patent scrapers, which just fill the flue, and
when attached to a rod and worked back and forth a few times the whole
length of the flue do admirable service.
Q. What harm will dirty flues do?
A. Two difficulties arise from dirty flues. If they become reduced in
size the fire will not burn well. Then, the same amount of heat will do
far less work because it is so much harder for it to get through the
layer of soot and ashes, which are non-conductors.
Q. What would you do if the throttle broke?
A. Use reverse lever.