The Anderson intelligencer. [volume] (Anderson Court House, S.C.) 1860-1914, 1884-02-14
Effects of Air on Boiler Explosions.

Gus boiler explosions has recently been
advanced in the Journal de France, in
which attention is drawn by experiments
made by Prof. Donny, of Ghent, and
which is certainly deserving Of critical
examination. The theory is based on the
presence or absence of air in the water,
and is thus described in the american
Engineer:
In this experiment ordinary water is
placed in clean glass tube, open at one
end, and boiled long enough to drive away
not only the air above the surface of the
water, but all the air dissolved in the
water. Then, when the upper part of
the tube is full Of pure steam, the mouth
is hermetically sealed and the tube left
to cool. When cool it is about half full
of water, above which is vapor of water
in a very low pressure. The tube being
thus prepared, its lower end is plunged
in bath of glycerine or oil, which is
gradually heated. No ebullition is yisi.
BILE in the tube when the temperature
reaches 1000. (2340F.) At13S0 (2400F,)
however the column Of water burst, as it
were, in two with sudden explosion,
and part of it is flung against the sealed
end with such force as often to break it
open.
Now, in industrial works it often hap.
pens that a boiler, having sbeen filled
with water, works for three or four hours
without receiving further supply; it
may then be cooled down, and the next
time it is wanted it may very probably
be fired up again without starting the
feed-pump, the water.level being judged
sufficiently high. But the water in such
boiler will be in the same condition as
that in the test tube, 4 e., it will be de.
prived of all air and consist of water be-
low and vapor above, the latter, however,
being probably at a much higher press
ure than that of the water in the tube.
This water has no free surface in its in.
terror, due to the presence of bubbles of
air, from which evaporation can take
place. Consequently, as in the test.tube,
there will be delay in vaporization, at
least until the expansion becomes great
enough to overcome the pressure of the
superintendent vapor, and then sud-
den flashing into steam, which will be of
the nature of an explosion, and may
easily overcome the resistance of the
boiler. The pressure thus attained may
be very great. Intbe test.tube the press.
urea at the temperature ofexplosionn (l3O'
C.) will be Sc times what may be taken as
the pressure of the superintendent vapor
in the boiler, as already observed. That
pressure will probably be much higher,
and the pressure of the explosion will
probably be much higher also.
-Four cases of explosion ere cited as
examples of this mode of action. The
first WAS at the mines of Hardinghem,
where, during the putting in of some
pumps, it was often necessary to stop the
engine and bank up the fires for time.
It had been noticed when this took
place the pressure vas very slow in rising
after the resumption of firing. On one
occasion, when this delay in recovering
the pressure had been very long, the en-
gineer, M. ODE, actually had his eye on
the pressure.guage, when he saw the
needle first vibrate sharply and then rise
by rapid steps to very high pressure.
At the same moment there was dull
roar within the boiler, slight shaking
of the ground, and the safety valves
opened wide, emitting clouds of spray
and steam. An explosion had, in fact,
occurred, but the boiler had been strong
enough to resist it. Subsequent exami-
nation showed that there was no sedi.
ment in the boiler, or any other apparent
cause for the occurrence.
The second case was at St. Laurent, in
a pair of boilers coupled together and
provided with heaters (bouilleurs) below
them, after plan common in France.
A stoppage had taken place, aud on re-
suming work the engine man found it
impossible to raise the pressure beyond
three atmospberes, at which it had been
standing. He, however, started the en-.
CINE, but it had not run more than few
minutes before the cylinder and steam
pipes were filled by rush of priming
water, dull sound was heard, and there
was a tremendous outburst from the
safety.valves. Here, again, no special
cause could be discovered for the occur
renee, which may fairly be set down to
che cause here stated.
In another case, at Roanne, the boiler
had been filed up an hour before stop
ping for dinner. When the time came
to resume work the fireman found the
water-level and pressure as they should
be, and started accordingly, but in twenty
minutes serious explosion occurred.
Lastly, at Cusset, boiler still hot from
the work of the day before, was fired up
at $50 A. NJ, and exploded one hour
after with terrible violence. In both
cases subsequent inquiry failed to reveal
any special cause for the disaster, for
which the present theory seems to offer
the best explanation.
To avoid this source of danger it will
be sufficient, as NJ. Vignes points out, to
make it rule always to feed boiler
Ct C..l no..