Improvements in Fire-doors and Ashpit Doors for Steam Boilers.
Year: 1896

page_text: Date of Application, 21st Dec., 1896
Complete Specification Left, 24th Dec., 1896-Accepted, 27th Feb., 1897
Improvements in Fire-doors and Ashpit Doors for Steam Boilers.
I, WILLIAM THOMAS HOBSON, residing at 4 Church Road Willesden in the
County of Middlesex, Engineer do hereby declare the nature of this invention to
be as follows:-
In the event of the explosion of steam boilers or parts of steam boilers, a firedoor
opening inwardly only and closing outwardly against its frame or casing at sides,.
top and bottom in such a manner as to form a seat or joint sufficiently close and
tight as to prevent the escape of the contents of the steam boiler and furnace into
the fire room thus endangering life, and forcing the exit of such escaping contents
by way of the flue and stack or funnel. To this end I provide a swinging door,.
having its dimensions larger than the frame, into the interior of which it fits,
working upon a pivot. It will necessarily follow that the greater the pressure
against the door in an outward direction, the tighter will it fit into the frame.
I provide a lever with balance weight attached in order to operate the door in the
direction required. Also a baffle plate, common to firedoors of furnaces. In
short a firedoor designed to act as a check valve against the escaping elements.
before mentioned.
Dated this 19th day of December 1896.
WILLIAM THOMAS HOBSON..
COMPLETE SPECIFICATION.
Improvements in Fire-doors and Ashpit Doors for Steam Boilers.
1, WILLIAM THOMAS HOBSON, residing at No. 4 Church Road Willesden, in
the County of Middlesex, Engineer, do hereby declare the nature of this invention
and in what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement:-
The object of my invention is to provide a firedoor and ashpit door for use more
especially in steam boilers, which, in the event of an explosion of the steam boiler
or parts thereof, will be able to withstand the outward pressure, thus preventing
the escape of the contents of the steam boiler and furnace into the fire-room or
stoke-hold in sufficient quantities to endanger the life of men in the fire-room, and
forcing the exit of such escaping contents by way of the flue and stack or funnel.
In the accompanying drawing,
Fig. 1 is a vertical section and Fig. 2 is a front elevation of my improved fire
and ashpit door.
In order that the door shall be able to withstand any pressure it may be subjected
to, I make it to open inwardly only and to close outwardly against its frame or
casing in such a manner as to form a seat or joint. To this end I provide a
swinging door 1, having its dimensions larger than the frame or casing 2, against

page_text: the interior of which it fits, turning upon an axle or pivot 3. By reason of its
greater dimensions it is impossible for the door to be forced outwards, and it will
necessarily follow that the greater the pressure brought to bear against it in
an outward direction, the tighter will it fit against its frame.
I form the upper portion of the frame or casing 2 into a hood 4, inside which the
radial portion of the door works as shown at 5 about its axle or trunnion pin 3, the
mouth or aperture of which frame is smaller in all its dimensions than the door,
the frame having end or side walls as shown at 6.
In combination with the above, I provide the lever 7 keyed to the axle 3, and
fitted with a balance weight 8, set in such a position relative to the door 1 that
said door is balanced when in its open position, but when the door is in its closed
position, returning to a point within a line drawn vertically through the centre of
the axle 3.
In combination with the above might be mentioned also the baffle plate 9 common
to fire-doors of furnaces.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :
(1.) A fire-door and ashpit-door opening inwardly only and closing outwardly
against its frame, said frame being smaller in all its dimensions at the points of
junction, substantially as described.
(2.) The combination of a fire-door and ashpit door closing outwardly against its
frame or casing with a suitable lever and balance weight operating said door,
substantially as described.
(3.) The combination of a fire-door and ashpit-door closing outwardly against its
frame or casing, a suitable operating lever and balance weight and a baffle plate
substantially as described.
(4.) The combination of a fire-door and ashpit door closing outwardly against its
frame or casing, a suitable operating lever and balance weight, with a baffle plate,
the whole designed to act as a check valve against the escaping elements
before mentioned, substantially as set forth.
Dated this 23rd day of December 1896.
WILLIAM THOMAS HOBSON.