concerning the operation and care of steam boilers.
Q. How is steam taken from the boiler?
A. By suitable piping leading from a steam dome on top of boiler.
Q. What is a steam dome and how is it made?
A. A steam dome is cylindrical in shape, is made usually of boiler
plate flanged and riveted over a hole on top of boiler.
Q. Of what use is a steam dome?
A. Its use is to afford space for dry steam to collect.
Q. What is a mud drum, and of what use is it?
A. The mud drum is cylindrical in shape, made of boiler iron flanged
and riveted over a hole on under side of boiler, in which mud and
sediment may collect, and is of great value on a return flue boiler.
Q. What are boilers furnished with so that they may be easily cleaned?
A. Man-holes and hand-holes.
Q. What are man-holes and hand-holes?
A. The man-hole is a hole cut in boiler large enough to admit a man and
is covered by a portable plate which can be fastened absolutely tight.
Hand-holes are small holes cut in boiler in convenient places into
which a hose can be placed and the boiler washed out and the mud and
scale removed. Hand-holes are covered with portable plates which can be
fastened absolutely tight.
Q. How can a boiler be protected from the cold?
A. By a non-conducting jacket which keeps off the cold, retains the
high temperature of the boiler and prevents the radiation of heat.
Q. What materials are used for jacketing a boiler?
A. Plaster, wood, hair, rags, felt, paper and asbestos.
Q. How are they applied?
A. Wood is put on in long strips close together like barrel staves,
fastened with hoops and usually covered with sheet iron. The other
materials are put close to the boiler and held in place by sheet iron
or canvas. They are sometimes put on with an intervening air space
between them and the boiler.
Q. What is the use of air space?
A. It protects the material from being burned or otherwise injured by
the heat.
Q. Is there no radiation through these coverings?
A. Yes, but the loss is very slight, as the temperature of covering
should never rise above what just seems warm to the hand.
Q. How should you feed water to a boiler?
A. Continuously during the whole time that steam is being used.
Q. Will a steam pump feed continuously?
A. Yes, by running the pump faster or slower according to the amount of
water required.
Q. Why is a continuous feed preferable?
A. Because it maintains the water in the boiler at a uniform level and
gives the most perfect action.
Q. Should precaution be taken in choice of water used in the boiler?
A. Yes. Always use water that is as clear and free from foreign matter
as can be procured, rain water preferred.
Q. What is the result of using impure water?
A. It will form a scale upon the flues and plates on the inside of
boiler.
Q. What harm does scale do?
A. In the first place scale is a non-conductor and prevents the heat
of furnace from producing its best effects upon the water and in the
second place it allows the plates and flues to become over heated and
burn.
Q. How can you prevent the formation of scale?
A. There are numerous compounds upon the market some of which are known
to be very reliable, but for ordinary purposes sal soda dissolved in
the feed water answers very well.
Q. What precaution should be taken in the use of sal soda?
A. Great care should be taken that too much is not used at a time. If
too much is used a great deal of trouble will be caused by the water in
the boiler foaming.
Q. How often should a boiler be cleaned?
A. It depends entirely upon the condition of the feed water used and
the amount of service exerted from it. It may vary from once or twice a
week to once in two or three months, or even longer.
Q. Does a boiler only require the regular cleaning?
A. No, it should be blown off three or four times a day by the surface
blow-off.
Q. Should the surface blow-off be left open any length of time?
A. No, only a few seconds at a time, say from fifteen seconds to a
minute, even longer on larger boilers, but the engineer must use his
own judgement in this matter.
Q. What does the surface blow-off do?
A. It blows out all the impurities that arise in the form of scum on
the surface of the water, thus lessening the amount of scale formation.
Q. How should a boiler be cleaned?
A. By blowing the water out at a low pressure of steam and after
cooling off wash out and scrape the inside, removing all scale and
sediment.
Q. How do you blow off your boiler?
A. By means of a blow-off valve situated at the bottom part of the
boiler.
Q. When should a boiler be blown off?
A. When the steam pressure entirely disappears and the water is at
boiling point, if boiler is set in brick work.
Q. Why not blow off under a full head of steam?
A. Because when blown off under pressure there is heat enough remaining
in the shell and flues to bake the scale upon the interior, thus
rendering it exceedingly difficult to remove.
Q. In what condition is the scale after blowing off at low pressure.
A. Some may be baked hard and attached to the flues and shell, but the
greater part will be soft and slushy so that it can be easily removed.
Q. How is this slush removed from the boiler?
A. If a fire box or return flue boiler, all the hand-hole plates should
be removed and as much of the slush as possible raked out; then a
hose is inserted and a stream of water forced in which will carry the
remainder out. The hose should be placed in the top holes first.
Q. Is it a good idea after blowing off a boiler to fill it with water
again without delay?
A. No. Because the boiler is hot, and if cold water is put in before it
is thoroughly cooled off the boiler will be subjected to severe strains
caused by the sudden contraction of the metal that is expanded by the
heat, which will injure it to a greater or less degree.
[Illustration: Garr-Scott Traction Engine.]