Vermont watchman and State journal. [volume] (Montpelier, Vt.) 1836-1883, 1863-01-30
STEAM BOILER FXpTOsIONs

ciples, embracing the high and low pressure,
marine. stationary, and the locomotive.
During this time | have improved every
opportunity Of examining boilers which have
exploded, to learn the cause Of the pheno-
menon. My experience of boiler explosions
goes to show that however possible it may
be to accumulate an excessive pressure with
the boiler, the actual explosions result in a
majority of cases from some defect in the
boiler, either visible or concealed. The ma
terial combining the fluid often gives way un-
der the ordinary pressure, to consequence OF
long use and decay. Boilers sometimes ex-
pode which are Of the best material, having
generated accidentally or otherwise, a super.
abundance of steam. Cases of this kind are
of seldom occurrence, however
Cylinder boilers, with return Aues, are pro-
badly more liable to explosion in consequence
Of collapse that those of the other form. -
Should the water fall below the lues they
will Immediately become hot, and fall into the
small quantity of water remaining in the
boiler, which will be instantly converted into
steam of expansive force, and an explosion is
inevitable. This style of boiler is now be-
ing superseded, both for steamboats, and fix
cd engines which desire high steam by that
Of the locomotive shape, which is more safe.
Boilers generating high steam, in this
country have their saiety-valyes loaded at from
20 TO 1870 pounds to the square inch and if
there is no defect in the material, or work
manship of the boiler it is perfectly safe at
this pressure. While running steamboat
in California several years since, having a
number Of small cylinder boilers made of the
best materials, so pounds were the working
pressure.
The low pressure or atmospheric engine, is
as its name purports, an engine generating
low steam, taking advantage of the atmos-
pheric pressure. The highest working pres
sure allowed by the Admiralty OF England,
Is Is pounds. In the American service, in
consequence Of their engines having superior
condensing powers, 25 pounds are allowable.
The question is often asked, wherein do
low pressure engines obtain in their great
power For the information of such will
say, that their power is derived from the great
area of their cylinders, and obtaining va
CUM which is constantly maintained Ivy con-
densing their exhausted steam. A good close
working low pressure engine will maintain a
vacuum of from Is to "a inches of mercury.
| was at one time on board of an English
steam tigate which obtained a vacuum, for a
short time, Of rs inches, equal to IL pounds
1t will De obvious to all, that boilers generat-
ing low steam are not so liable to exposure
as those containing steam Of greater density
Government boilers are made of the best ma
terial, often inspected, and are under the
supervision and control OF competent engin-
GERS, which almost entirely precludes an ex-
plosion.
Boilers in constant use should be proved at
least once year, by forcing water into them
until the safety-valve is lifted, which should
be loaded with at least twice the working
pressure for the occasion. If the boiler will
not stand this test, it is not safe, and either
the working pressure should be diminished,
or Us strength increased. All boilers having
large fues, are subject to collapse, should the
water fail below the fues. There is another
species of danger, which arises from the de-
posits o! solid substances. Almost any kind
of water that is used for boilers contains
more or less earthly and saline matter. The
constant evaporation is replaced by new sup
pites OF the Same impure matter, and the SOL
uble portion. or mechanical impurities, is con-
sequently accommodating, Crust, thus formed
on the lower part of the boilers, and the sur
face covered with them. being no longer in
contact with the water, may be heated red hot.
The boilers will obviously become weak in
their parts, and liable to burst
These deposits become frequent and CO.
pious, when sea water is used and it has
been found necessary in consequence, to
cleanse the boilers of steamboats, that navi-
gate salt water at least once week.
Tho locomotive is double acting, high
pressure engine, working at right angles,
and is one of the most magnificent and use
fu pieces of mechanism ever invented by
man, antic pating his almost every wish ad-
! ministering to has comfort, both along the
, sultry plains of India and amid the snowy
plains of Vermont. The locomotive boiler
contains the greatest amount Of heating sur
face OF any one in use The forward or CYL.
inder portion, contains large number OF
copper tubes or hues, and the rear is almost
exclusively occupied by the fire box which is
its vulnerable side. The outside or shell OF
this boiler never comes in contact with the
+ FIRE, consequently will last much longer than
the fire box.
The safety of the locomotive is not endan-
gered, as many suppose, by allowing the wa
ter to fall below its fire surface. There are
large number of small hues, and collapse is
impossible. Should the fiues become heated
they will have to be replaced by new ones
| have seen this operation performed several
times. Locomotive engines sometimes ex-
plode, in consequence Of their fire boxes be-
coming weak and worn out. The engineers
are almost always invariably killed. and the
public are told thaa they allowed the water to
fall below the point OF safety, and persisted as
victims to their own negligence.
Hence the necessity of discussing the pub
} lie mind upon this point.
Some engineers maintain that after the wa
ter has completely left boiler, then large
quantities of explosive gas is generated,
which necessitates an explosion. All the gas
that there is generated, l think, is in the
minds Of those who endeavor to promulgate
such fallaeious and deceptive hypothesis. We
assert, without the fear of successful contra
diction, that steam boilers may be made to be
used, with as much safety, as the boiling OF
water in a tea-kette, under proper laws and
that by thorough system of inspection, ex-
Plosions may be completely prevented.
Ii. 2. FLINT,
Engineer on VT. c. r. r.
NBw YORK, Jan. "a.
BY arrival Of the British steamship She'll
drake, we have the following intelligence