The Vancouver independent. (Vancouver, W.T. [Wash.]) 1875-1910, 1881-07-28
A New Theory Of Boiler Explosion.


genuine boiler explosion in
Pittsburg few days ago has awakened
a new interest in this subject. The ex-
periments were made at Munhall Farm,
on the Monongahela river, nine miles
above Pittsburg, where the United
States Government Commissioners made
signal failures in their attempt to pro.
duce the same results few years ago.
The same foundations, furnaces, water
supply and bomb proofs were used on
this occasion. The boiler was made of
the very best iron, and showed tensile
strength of 624 pounds to the square
inch, according to the United States
standard. It was six feet in length by
thirty inches in diameter. Before being
taken to the ground it was tested by the
boiler inspector of this county and pro-
nounced one of the best and most perfect
steam boilers he had ever examined.
The cylinder of an old steamboat en-
CINE was connected with the boiler by
means of two-inch pipe, in which was
fitted quick-liftipg valve. The steam
was permitted by means of this valve to
enter the cylinder in the same manner
as it enters the cylinder of any ordinary
engine, with the exception that it was
not cut off suddenly, as in working en-
CINE. Had it been, Mr.. Lawson claims,
the explosion would have been still
more certain. When the pressure
reached a certain point the furnace was
fed with petroleum by means Of
small rope connected with tank located
at safe distance. The majority
of those who saw the boiler were of
the opinion that it would safely stand
500 pounds pressure, and would not give
way to less than 600. In order to save
time no test was made until pressure OF
1876 pounds to the square inch had been
obtained. The valve was then lifted
quickly, and the steam rushed into the
cylinder rapidly, but with no more effect
than to produce a shock distinctly no.
ticeable by those in the bomb-proof.
The final test was made at a pressure
of $50 pounds, little over half the
capacity of the boiler. At this time the
water was eight inches above the fire
line, the boiler being at least three
fourths full. No sooner was the cylin.
der filed with the rushing steam than q
slight shock was felt, FOLLOWED by ter
rife report. Vast volumes OF steam en-
veloped everything, but there were no
signs of any hot water, it all having
burst into steam when the pressure was
removed. This accounts for the absence
of water marks in the vicinity of boiler
explosions, which has often led to the
conclusion that they were caused by the
extremely low water. The report had not
died away before shower of condensed
steam began falling, accompanied by
pieces of iron, bricks, steam pipes and
other debris. Scarcely vestige OF the
furnace or boiler was left. The latter
had not merely given way at single
point. but was literally torn into frag-
mants. " One. of the largest pieces yet
and foot wide. 1t had been b165%Rfi
fully half mile. One of the heads was
found nearly half a mile from the bomb
proof. The other one had not been
found at last accounts. The most Of the
pieces picked up were of irregular shape,
with very ragged edges, showing the iron
to have been of excellent quality.
In a recently published article Mr..
Lawson claims that the only explosive
element in steam boiler is super-heated
water; that water, highly per-heated,
explodes by q sudden reduction of the
pressure from its surface by bursting
into steam, which instantly fills over
100 times the space occupied by the
water. When the water is surerhested
the engineer opens the cylinder port,
and instantly the steam fills the cylinder,
creating vacuum to that extent over
the superheated water in the boiler, Q
portion OF which bursts into steam to re-
store the reduced pressure, instantly
striking every square inch Of the
boiler with conclusive force many
fold greater than the regular
pressure Of the steam, and consequently
numerous explosions occur inst as steam
is turned into the cylinder at starting
and before its passage from the boiler
has become uniform. Another prolific
source Of explosions, Mr.. Lawson claims,
is the sudden condensation of steam over
the superheated water in the boiler, there
by creating vacuum and consequent re-
moval of pressure, when instantly the
water bursts into steam with q concus-
sive force that is generally irresistible.
Mr.. Lawson has invented boiler which
he believes to be proof against explo-
sions of this kind, It is constructed with
q partition intervening between the fues
and the top Of the boiler, thus creating
. steam compartment over the water, to
be supplied with steam from the water
valves in the partition, which
valves; to insure safety, must be smaller
in the aggregate than the port or valve
which the cylinder is fed from