IMPROVEMENTS IN APPARATUS FOR THE PREVENTION OF EXPLOSIONS AND OTHER DERANGE- MENTS IN STEAM BOILERS
Year: 1883

page_text: LETTERS PATENT to Thomas Constantine Fawcett and John Crosby Hargreaves
16
both of Leeds in the County of York for an Invention of IMPROVEMENTS
IN APPARATUS FOR THE PREVENTION OF EXPLOSIONS AND OTHER DERANGE-
MENTS IN STEAM BOILERS
PROVISIONAL SPECIFICATION left by the said Thomas Constantine Fawcett
and John Crosby Hargreaves at the Office of the Commissioners of Patents on
the 6th February 1883.
THOMAS CONSTANTINE FAWCETT and JOHN CROSBY HARGREAVES both of Leeds
in the County of York "IMPROVEMENTS IN APPARATUS FOR THE PREVENTION OF
EXPLOSIONS AND OTHER DERANGEMENTS IN STEAM BOILERS
"
This Invention relates to apparatus for preventing boiler explosions arising from
excessive steam pressure and also other derangements which are liable to happen
when the water in the boiler is above or below the high or low water line.
The apparatus consists of a dead-weight safety valve placed in the roof of the
boiler enclosed within a steam chest. A steam pipe from the said chest is carried
into the flue above the furnace or grate bars either inside or outside the boiler so
that any steam escaping through the safety valve is discharged upon the coal or
fuel and checks the combustion thereof and so reduces the quantity of steam
generated.
For indicating high and low water, we place a pair of levers in the water space
to one of which is attached a float in such a manner that when the float rises or
lowers to a certain extent one or other of the levers shall act on the weight of the
safety valve and raise the same thereby allowing steam to escape into the furnace.
When the safety valve is heavily weighted a secondary valve may be used for
indicating the level of the water.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Thomas Constantine Fawcett and John Crosby Hargreaves in the
Great Seal Patent Office on the 4th August 1883.
THOMAS CONSTANTINE FAWCETT and JOHN CROSBY HARGREAVES, both of Leeds
in the County of York "IMPROVEMENTS IN APPARATUS FOR THE PREVENTION OF
EXPLOSIONS AND OTHER DERANGEMENTS IN STEAM BOILERS
"
This Invention relates to apparatus for preventing boiler explosions, arising from
excessive steam pressure and also other derangements which are liable to happen
when the water in the boiler is above or below the high or low water line.
The apparatus consists of a dead-weight safety valve placed in the roof of the
boiler enclosed within a steam chest. A steam pipe from the said chest is carried
into the flue above the furnace or grate bars, either inside or outside the boiler so
that any steam escaping through the safety valve is discharged upon the coal or
fuel and checks the combustion thereof and so reduces the quantity of steam
generated.
For indicating high and low water, we place a pair of levers in the water space,
to one of which is attached a float in such a manner that when the float rises or
lowers to a certain extent, one or other of the levers shall act on the weight of the
safety valve and raise the same, thereby allowing steam to escape into the furnace.
When the safety valve is heavily weighted a secondary valve may be used for
indicating the level of the water.
A is the
In order that our Invention may be better understood, we herein give reference
to the accompanying sheet of Drawings, wherein Fig 1 is longitudinal section of
a steam boiler and furnace with our Improvements applied thereto.
furnace placed within the flue B, and C is the shell of the boiler, all arranged in
the usual manner. A steam chest D is fixed on the upper part of the boiler and
is in direct communication with the furnace by means of the pipe E. A weighted
valve F is employed, placed in the roof of the boiler and enclosed within the steam
chest. It will be understood that when there is excessive pressure of steam in the
boiler that the valve F will be opened, thereby allowing steam to escape into the
chest D and pass down the pipe E onto the furnace and thus reduce the heat
thereof and diminish the quantity of steam. By this means explosions by undue
steam pressure are avoided.
The same apparatus as above described can with equal advantage, be employed
to check the generation of steam when water in the boiler is above or below the
estimated water line. In addition to the apparatus already described, we employ
an arrangement of compound levers consisting of an horizontal lever H passing
through an opening in the weight I. Another lever J is employed, hinged upon
the fulcrum M and having at one end a float N which is raised or lowered
according to the varying height of water in the boiler. It will be seen and easily
understood that when water is low in the boiler, the float N will be lowered also
to such an extent as to bring the projecting point a of the lever J underneath the
weight I whereby the valve F is opened, allowing steam to enter the steam chest
and pass down the pipe E into the furnace. On the other hand if the water is too
high, the lever and float will ascend as shewn in dotted line, the pin b on the said
lever J being brought into contact with the lever H which raises the weight and
opens the valve as before explained. Having now shewn and described our
Invention and the manner of carrying the same into practice, we would have it
understood that we do not confine ourselves to the exact details herein shewn and
described, as the same may be varied without departing from the nature of our

page_text: Invention, the valve F and pipe E for instance need not necessarily be on the top
of the boiler, but may be placed in any convenient position providing the orifice of
the pipe is in communication with the fire, but what we claim is-Firstly. The
combination of the valve F, steam chest D and pipe E for purposes substantially as
described. Secondly. The use and employment of the compound levers H and J in
combination with parts F, D and E for the purpose substantially as shewn and
described. In witness whereof I the said Thomas Constantine Fawcett for and
on behalf of myself and the said John Crosby Hargreaves, have hereunto set
my hand and seal this third day of August in the year of our Lord 1883.
THOS C FAWCETT
(LS)