Improvements in the Bottoms of Fire Grates, Furnaces, and Coal Stoves.
Year: 1893

page_text: Date of Application, 24th July, 1893
Complete Specification Left, 13th Apr., 1894-Accepted, 12th May, 1894
PROVISIONAL SPECIFICATION.
Improvements in the Bottoms of Fire Grates, Furnaces, and
Coal Stoves.
JOHN THOMAS JOHNSON 45 Great Ancoats Street Manchester Ironmonger do
hereby declare the nature of this invention to be as follows:-
My improvements in firegrate, furnace and coal stove bottoms consists in providing
means for the admission and conduction of currents of air to the interiors of
fires in ordinary firegrates, furnaces and coal stoves by which a more perfect
combustion of fuel is attained the fires are continually kept bright, and in a great
measure the usual accumulations of ash and dust are avoided by reason of the
greater incandescence of the burning fuel. My improvements also prevent the
passing off of the vapours of the burning fuel in the form of smoke and soot, thus
considerably economising the amount of fuel consumed.
These objects I attain in a convenient manner by forming one or more hollow
projections or air chambers of suitable shape and rising to a convenient distance
above the bottom and either cast in one piece with the bottom or made separately
and securely attached to the bottom in any necessary position..
These "air-chambers" should penetrate the fire to a height of from one to
two inches or more and have either on top or in sides, one or more openings. The
coals are piled round the air chambers, which, when the fire is ignited become
red-hot thus superheating the air contained within, and causing it to pass through
the openings into the midst of the burning fuel, cold air being constantly drawn into
the air chambers to take the place of the warm air which has passed into the fire.
These air chambers may be placed in different positions on the bottoms and for
some kinds of firegrates one only, placed centrally may be used, but for ordinary
ranges or fire grates I prefer to use two, placing one at each end of the grate
bottom, in order that the air may be more evenly distributed through the fire.
For other kinds of fire grate bottoms, such as Leamington ranges, furnace or set pot
fire bottoms a greater number may be used if required but I find that generally two
is sufficient for a very large fire. When the air chambers are made in taper form
having the openings or air inlet at the top or apex I find that it is better to have
the apex slightly notched so that the passage of air is not impeded by the coals or
cinders becoming packed in the apertures, but when the apertures or openings are
made in the sides of the air chambers the air is diffused amongst the coals with very
little chance of obstruction from this cause.
My improvement is specially adaptable to any form of grate bottom or false fire
grate bottom and in some cases I may elect to form the air chambers so that portions
of them may project at both the top side and also at the under side of the bottom
and in this form and also when the air chambers are made on the top side only
but cast in one piece with the bottom the cost of production would not exceed the
price at which any fire grate bottom or false fire grate bottom is now made, such
articles being usually sold by weight.
When the air chambers are made separately from the body of the firegrate
bottom suitable means of securely attaching them in their proper positions may
be provided and if necessary they may be made so that it would be possible to
detach them from the bottoms and to replace them with others in case they
became burnt away before the main body of the bottom at very little trouble and
expense.
Dated this 22nd day of July 1893.

page_text: שש
Improvements in the Bottoms of Fire Grates, Furnaces, and
Coal Stoves.
JOHN THOMAS JOHNSON 45 Great Ancoats Street Manchester Ironmonger 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:-
Upon the surface of the bars which form the bottoms of fire-grates, stoves or
ranges of any kind, and upon the surface of the loose bottoms commonly termed
"false bottoms" and also upon the fire surface of the loose bottoms with vertically
barred fronts usually called "coal-savers" and of any other kind of bottom used
air-chambers."
for fire-grates, I make what I will for convenience describe as
These air chambers are preferably made in the shape of a dome or other
pyramidal form, and rise up above the surface of the bottoms to a suitable
distance.
These domes are hollow and open at the base, and are placed upon the fire
bottoms with the broadest and open end downwards, and are pierced with slots
commencing near the crown or apex gradually widening as they pass vertically
downwards, and extending through to the underside of the bottoms.
The object of these air chambers is to furnish draughts or currents of air to the
interiors of fires, so that the fuel may be more completely consumed, and by doing
so preventing any great accumulation of ash or dust and also reducing the amount
of smoke given off by the burning fuel. I do not claim that the idea of conveying
currents of air to the interiors of fires is new, as I am well aware of several
inventions having the same object, but I claim for my invention that by combining
air chambers of suitable shape rigidly attached to or made integrally with fire-
grate bottoms, the object is attained in a convenient and satisfactory manner, as
there is no liability of the air chambers becoming displaced by the insertion of the
poker between the grate bars, and so the fires are kept continually bright and clear
during the whole time they are ignited.
One or more of these air chambers may be used to each fire grate or false
fire-grate bottom, but I recommend that for ordinary grates or ranges two should
be used, fixing one at a little distance from each end of the bottom, so that the
currents of air may be well diffused, and become intermingled with the burning fuel
in every direction.
I do not confine myself to any particular design, outline or shape of these air
chambers, nor to any particular size, shape or number of slots for the passage of
the air, as it will be obvious that any pattern of air chambers rigidly attached to
the fire grate bottoms, and extending to a suitable height into the interior of the
fires, and especially when there is a complete clearance at the underside of the
air chambers, will have the same effect, but I recommend the dome-shaped pattern
with from four to six apertures or slots in the circumference as the air is then
more evenly distributed, and there is entire freedom from obstruction to the free
ingress of the air by the packing of the fuel into the apertures.
In some cases I prefer to make the air chambers separate from the body of the
bottom and I then provide lugs at the base of the air chamber for attaching them
to the bottoms, or instead of the lugs I may make a projecting ring shaped base
with suitable openings left in for securing the air chambers to the bottoms, by any
suitable device as by means of bolts and nuts or by cotter pins or clinch rivets or
other satisfactory method. When the air chambers are so made separate from the
body of the bottom, the bottom should be made with openings of the same size
and preferably of similar shape as the interior of the air chamber to be fitted upon
it, so that any ash or dust passing through the slots or apertures of the air

page_text: chambers falls to the underside of the grate and does not cause any impediment or
obstruction to the passage of the air.
In another modification I provide the air chambers with a web of the same metal
or other fire-resisting material of which the air chambers are made between each
aperture in order to strengthen the crown and sides of the air chambers and to
direct the currents of air with greater velocity through the apertures into the midst
of the burning fuel.
These webs may be added either to the air chambers made separately or to those
moulded in one piece with the bottom, as the only thing necessary to do to apply
them is to add strips in the proper places inside the ordinary patterns which are
used for moulding from and the air chambers may then be moulded with the webs in
as easily as without them.
The drawings herewith shew the invention as applied to a "false bottom," and
are sufficient to indicate the application of the invention to any shape or size
of fire bottom. The proportions of the bottoms may be varied at will, as
for instance, in some patterns of firegrates the bottoms are required much wider
than others, but even when wider than the proportions shewn on drawings the air
chambers may be used of the same dimensions as on the smaller and narrower
patterns or they may be enlarged to any extent desired.
In Fig. 1 I shew a side elevation and also a sectional elevation of my improve-
ment, the raised portions marked A representing the air chambers, and B the
apertures or slots for the passage of the air.
In every case where the same letters appear on each separate drawing they are
intended to refer to the same portion as on every other of the drawings.
The dotted lines through the bar beneath the dome in the side elevation of
Fig. 1 shew the continuation of the slots through the body of the bottom to the
underside.
In the sectional portion of Fig. 1 I shew the interior view of one only of the
apertures.
Fig. 2 is a plan of the surface of the fire-bottom and shews the approximate
disposition when five of the apertures are used, and it will be readily seen from the
drawing how a greater or lesser number of slots or apertures may be used. The
portion marked C in Fig. 2 shews the apparent opening in the firebottom at the top
side, if the dome shewn on Fig. I was removed at the level of the surface, and
also indicates a desirable pattern of opening to be used with the addition of the air
chambers of the shape and arrangement shewn at Fig. 4, but with other patterns of
air chambers I should vary this arrangement in any manner necessary as for instance
I may elect in some cases to form the air chambers of oval or similar shape
having the broadest side parallel to the length of the bars and then I should make
the opening C Fig. 2 in the fire bottom, of the same shape as being most suitable
for the purpose. The portion marked F on Fig. 4 is the side elevation of the
projecting rim which contains the holes for fastening the air chambers in the proper
position directly above the opening C in Fig. 2. Fig. 3 shews the end view of
the fire bottom with the air chamber in position G shewing the section of the
longitudinal bars.
In another form I may make these air chambers of funnel shape and place a
number of them at equal intervals along the length of the bottoms, the air
openings in this case being at the apex as the broadest side is placed nearest the
bars in every instance.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim is
1. The application of raised air chambers in a fixed and immovable form, with
suitable apertures for the admission of currents of air, to the bottoms of fire grates,
stoves or ranges.
2. The combination in a fire bottom of an opening of suitable shape and a

page_text: raised air chamber, capable of being securely attached to the bottom and readily
detached.
3. The making of fire bottoms with upright front bars attached in combination
with the air chambers described and illustrated.
4. The making of fire, stove or range bottoms in the manner described and 5
illustrated.
Dated this Eleventh day of April 1894.