IMPROVEMENTS IN APPARATUS FOR CONTROLLING THE DRAUGHT OF STEAM BOILER FURNACES
Year: 1872

page_text: LETTERS PATENT to Thomas Irving, of No. 17, Gracechurch Street, in
the City of London, for the Invention of “IMPROVEMENTS IN APPARATUS
FOR CONTROLLING THE DRAUGHT OF STEAM BOILER FURNACES."
Sealed the 18th June 1872, and dated the 2nd January 1872.
PROVISIONAL SPECIFICATION left by the said Thomas Irving at the
Office of the Commissioners of Patents, with his Petition, on the
2nd January 1872.
I, THOMAS IRVING, of No. 17, Gracechurch Street, in the City of
London, do hereby declare the nature of the said Invention for "IM-
PROVEMENTS IN APPARATUS FOR CONTROLLING THE DRAUGHT OF STEAM BOILER
FURNACES," to be as follows:-
This Invention has for its object improvements in apparatus for con-
trolling the draught of steam boiler furnaces, and the improvements
relate to apparatus such as is described in the Specification of a Patent
granted to Robert Barrett on the 19th July 1862 (No. 2060), where the
opening and closing of a damper in the chimney flue is controlled by the
pressure of steam from the steam boiler acting upon a diaphragm, above
which are weighted levers connected by a rod with an arm on the axis

page_text: of the damper, so that when the diaphragm is raised by the steam the
damper closes, and when the pressure of steam decreases and the
diaphragm descends the damper opens and gives a freer draught to the
furnace. The axes of the damper rest on horizontal knife edges or
bearings formed in a frame which is set in the chimney flue, and the
damper when closed shuts against the front and back edges of this frame.
The frame is also set in the flue at an angle so that a slight turn of
the damper may close the flue. This arrangement of apparatus for
regulating the draught has however this disadvantage, that the frame
being set in the brickwork of the flue is liable to get loose, and the
proper working of the apparatus so interfered with.
My improvements have for their object to remedy this inconvenience.
For this purpose, in place of setting the frame directly into the brick-
work flue, I fix it within a metal box forming a lining to the fluc, and
through one side of the box a slot is formed through which passes the
connecting rod which connects the lever arm on the axis of the damper
with the levers upon which the diaphragm acts. On the outside of the
casing a cover is bolted to enclose this slot, and the connecting rod rises
up through this cover. The whole of the apparatus is thus independent
of the brickwork of the flue, and is not liable to be put out of working
order.
In place of the frame carrying the axis of the damper being fixed at
an angle within a metal box or lining of the flue as above described,
such box may be cast with internal flanges projecting from it for the
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Thomas Irving in the Great Seal Patent Office on
the 2nd July 1872.

page_text: WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Second day of January, in the year
of our Lord One thousand eight hundred and seventy-two, in the thirty-
fifth year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said Thomas Irving, Her special license that
I, the said Thomas Irving, my executors, administrators, and assigns,
or such others as I, the said Thomas Irving, my executors, adminis-
trators, and assigns, should at any time agree with, and no others,
from time to time and at all times thereafter during the term therein
expressed, should and lawfully might make, use, exercise, and vend,
within the United Kingdom of Great Britain and Ireland, the Channel
Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN APPARATUS
FOR CONTROLLING THE DRAUGHT OF STEAM BOILER FURNACES," upon the con-
dition (amongst others) that I, the said Thomas Irving, my executors
or administrators, by an instrument in writing under my, or their, or
one of their hands and seals, should particularly describe and ascertain
the nature of the said Invention, and in what manner the same was
to be performed, and cause the same to be filed in the Great Scal
Patent Office within six calendar months next and immediately after
O the date of the said Letters Patent.
NOW KNOW YE, that I, the said Thomas Irving, do hereby declare
the nature of the said Invention, and in what manner the same is to
be performed, to be particularly described and ascertained in and by the
following statement thereof, that is to say :-
-
This Invention has for its object improvements in apparatus for con-
trolling the draught of steam boiler furnaces, and the improvements
relate to apparatus such as is described in the Specification of a Patent
granted to Robert Barrett on the 19th July 1862 (No. 2060), where the
opening and closing of a damper in the chimney flue is controlled by the
0 pressure of steam from the steam boiler acting upon a diaphragm, above
which are weighted levers connected by a rod with an arm on the axis
of the damper, so that when the diaphragm is raised by the steam the
damper closes, and when the pressure of steam decreases and the
diaphragm descends the damper opens and gives a freer draught to the
5 furnace. The axes of the damper rest on horizontal knife edges or
bearing formed in a frame which is set in the chimney flue, and the
damper when closed shuts against the front and back edges of this frame.
The frame is also set in the flue at an angle so that a slight turn of

page_text: the damper may close the flue. This arrangement of apparatus for
regulating the draught has however this disadvantage, that the frame
being set in the brickwork of the flue is liable to get loose, and the
proper working of the apparatus so interfered with.
My improvements have for their object to remedy this inconvenience.
For this purpose in place of setting the frame directly into the brick-
work flue I fix it within a metal box forming a lining to the flue, and
through one side of the box a slot is formed through which passes the
connecting rod which connects the lever arm on the axis of the damper
with the levers upon which the diaphragm acts. On the outside of the
casing a cover is bolted to enclose this slot, and the connecting rod rises
up through this cover. The whole of the apparatus is thus independent
of the brickwork of the flue, and is not liable to be put out of working
order.
Figure 1 shows a side view; Figure 2, a longitudinal section; and
Figure 3, a transverse section of apparatus constructed as above
described for controlling the draught of steam boiler furnaces. In
these Figures a is the damper supported on axes 6 which rest on
horizontal edges c formed in the frame d. This frame is as above
described fixed within a box e, by preference cast iron, the several
sides of which are cast separately, and with lugs e' upon them to allow
of them being connected to one another by bolts and nuts, as shewn in
the Drawings. The frame 6 is also secured in its place in the box e by
bolts and nuts, as shown. On the axis b at one side of the damper is an
. arm f, which at its end is bent outwards, and passes through a slot 9 in
the side of the box; h is a cover either cast or bolted on to this side of
the box, and enclosing the slot 9; passing up through this cover is a
connecting rod k, by which the outer end of the lever arm is to be
coupled with the weighted levers which are in connection with the
diaphragm as before mentioned. The box e is made just to fit within
the chimney flue from the steam boiler furnace, as shewn in the per-
spective view, Figure 4, and form a lining to it; thus the position of
the apparatus will not be affected by any imperfections arising in the
brickwork of the flue, and its proper working is ensured. The general
arrangement of the whole apparatus is shewn at Figure 4 in order that
its manner of working may be clearly understood.
In place of the frame d carrying the axis of the damper being fixed
at an angle within a metal box or lining of the flue, as above described,

page_text: such box may be cast with internal flanges projecting from it for the
damper to shut against, and the edges or bearings upon which the axes
of the damper are to rest may likewise be formed in the sides of the box
or lining. I however prefer the arrangement above described and shewn
in the Drawings hereunto annexed.
Having thus described the nature of my Invention, and the manner
of performing the same, I would have it understood that I claim the
employment of the metal box or lining of the chimney flue in com-
bination with the damper and apparatus in connection therewith,
substantially as herein-before described.
In witness whereof, I, the said Thomas Irving, have hereunto set
my hand and seal, this First day of July, in the year of our
Lord One thousand eight hundred and seventy-two.