Yorkville enquirer. [volume] (Yorkville, S.C.) 1855-2006, 1884-02-07
slistellameuns &eadiuq.
EFFECT OF AIR Oy BOILER EXPLOSIONS.

y
boiler explosonshas recently been advanced
in the Journal de France, in which atten-
ton is drawn by experiments made by Prof.
Donny, of Ghent, and which is certainly de-
serving of critical examination. The theo-
ry is based On the presence or absence OF air
in the water, and is thus described in the
Americdn Engineer:
In this experiment ordinary water is
placed in a clean glass tube, open at one
end, and boiled long enough to drive away
not only the air above the surface of the wa
ter, 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 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 visi-
BILE in the tube when the temperature reach
es 1902 G. (2340 F.) At 1882 (24Oo F.,) how
ever 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 happens
that boiler, having been filled with water,
ceiving further supply; it may then be
cooled down, and the neXttime it is wanted
it may very probably be fired up again with.
out starting the feed-pump, the Water-level
being Judged sufficiently high. But the
water in such a boiler will be in the same
condition as that in the test-tube, e., it
will be deprived of all air and consist of wa
ter below and vapOr above, the latter, how
ever, being probably at a much higher pres
sure than that of the water in the tube.
This water has no free surfaces in its inte-
ror, 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 over
come the pressure of the superintendent
vapor, and then a sudden flashing into
steam, which will be of the nature OF an eX-
ance of the boiler. The pressure thus at
tained may be very great. In the test-tube
the pressure at the temperature of explosion
Q3S0 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 are cited as eXam-
pies 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. 1t had been noticed
that when this took place the pressure was
very slow in rising after the resumption OF
firing. On one occasion, when this delay IN
recovering the pressure had been very long,
the engineer, NJ. ODE, actually had his eye
on the pressure-gage, when he saw the nee
die first vibrate sharply and then rise byrap-
id steps to very high pressure. At thesame
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
examination showed that there was no sedl-
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. n stoppage had
taken place, and on resuming work the en-
CINE man found it impossible to raise the
pressure beyond three atmosphereS, at
which it had been standing. He, however,
started the engine, but it had not run more
imam Il lew llllluleo USlolC IhS ~ s.i''
steam pipes were filled by a rush OF prlmlng
water, a dull sound was heard, and there
was a tremendous Outburst from the safety
valves. Here, again, no special cause could
be discovered for the occurrence, which may
fairly be set down to the cause here stated:
In another case, at ROanne, the boiler had
been filled up an hour before stopping for
dinner. When the time came to resume
work the fireman found the Water-evel and
pressure as they should be, and started ac-
corlingly, but in twenty minutes serious
explosion occurred. Lastly, at Cusset, a
boiler still hot from the work of the day be-
fore, was fired up at $40 A. NJ, and eXplod-
ed 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. Nignes points out, to make
it a rule always to feed boiler when it is
first fired up after standing. This will have
the double effect ofloWering the pressure and
of facilitating evaporation by distributing
the mass of water in the boiler and charg-
ing it to some extent with bubbles of air.
Meanwhile, the facts he has adduced are
certainly sufficient to warrant belief that
we have here a key to many cases Of
boiler explosions which have hitherto been
wrapped in mystery, and it seems very
desirable that careful and precise expert
ment should be undertaken to prove or dis
prove the production, on a large scale, of
the peculiar phenomena thus shown to eX-
ist in laboratory experiments.