AN IMPROVED AIR AND SMOKE VALVE
Year: 1864

page_text: PROVISIONAL SPECIFICATION left by Thomas Boyle at the Office of
the Commissioners of Patents, with his Petition, on the 10th March
1864.
I, THOMAS BOYLE, of 81, Gray's Inn Road, London, in the County of
Middlesex, Lighting and Ventilating Engineer, do hereby declare the nature
of the said Invention for "AN IMPROVED AIR AND SMOKE VALVE," to be as
follows:-
My improved air and smoke valve consists essentially of a pendant swinging
valve composed of air-tight flexible material hanging vertically when at rest
before a diagonally formed opening, which leaves it free to swing in one
direction from the vertical to the horizontal position, while confining its
action in the opposite way to a more or less limited deviation from the vertical
line in which it hangs. This valve is intended to be applied as a ventilator to
chimney breasts, into chimnies between interior rooms or apartments of any
kind, or between these and the open air, also as a preventive of down draught
in chimneys, and in every other description of air or smoke shaft. As a
chimney breast ventilator I apply it in practice as follows:-I make first
an oblong cast-iron box or frame similar in external outline and general
dimensions to the common Arnott valve frames. Both ends of this box are
open and parallel with each other, and on one end a flange is thrown outwards
to a right angle with the sides of a sufficient width to cover over the sides of
the aperture in the wall when the box is fixed in its proper position therein;
I fix this box permanently with cement in a suitable aperture made for it in
the chimney breast. I next make a second box of the same material of

page_text: suitable length and breadth to fit into the first box, and having a similar
flange thrown outwards on one end of it, which flange on this second box
being inserted in the first rests upon and overlaps the flange of the first box.
This second box is made less in depth than the first, and its inner opening
instead of terminating in four sides of equal length, and being consequently
parallel with its face, is cut off from top to bottom through the two sides, in
a line sloping inwards at a greater or lesser angle from a vertical line drawn
parallel with its face. Thus the top side of this box is the longest measured
outwards from the vertical line of the face, the bottom the shortest, while the
two remaining sides slope gradually in the direction of a line drawn from top
to bottom between the two. On this sloping end or opening of this box a
flange is thrown inwards from each of the sides, that from the top being about
three-eighths of an inch in width, those-from the two lateral sides about three-
quarters of an inch each, and that from the bottom about one inch. The
space comprised within this flange I now either provide with an open
grating of any suitable sort, or leave it quite open. I use valves of two sorts
some of a flexible and some of a rigid construction. If I use the former, then
I require a grating in the space within the flanges as a support across the
back of the valve, if the latter I need no support beyond the flanges. The
valves are composed of any air-tight flexible material, such as india-rubber,
leather, leather cloth, or any similar material, but I prefer in practice vul-
canized sheet india-rubber. I apply this material either in its natural flexible
state without any further preparation or addition, or I render it rigid in
various ways, as by stretching it upon a thin sheet of tin or other suitable
metal, or by attaching narrow strips or small tubes of any light sheet metal in
any convenient manner to one or more of its edges. I proceed by cutting the
india-rubber into pieces corresponding in size with the openings just described
on the inner end of box No. 2, making them to lap well over upon the flanges
on all sides, and whether stiffened or flexible, I attach them in the same
manner along the top or narrowest flange of the opening, by means of a strip
of metal of the same length and breadth as the flange screwed down upon
the india-rubber and into the flange. Thus secured all along one edge, the
remainder of this valve is so far free to swing to-and-fro by the motion of the
air passing in either direction through the ventilator. In one direction only
however, is it free to swing to its fullest extent, in the other a slight devia-
tion from the vertical line in which it hangs while at rest brings it in contact
with the remaining flanges of the opening whereby the aperture is closed, and
the further passage of air in that direction rendered impossible. By this
arrangement the working consists in all cases of a swinging or vibrating

page_text: motion of the delicately flexible material of the valve, whereby the most
sensitive, unceasing, and uniform action of the same is maintained, and the
necessity for employing any metallic hinge or bearing part liable to oxidise
or get out of order is avoided. The vertical and partially open position
of the valve when at rest provides that no obstruction, however slight,
shall ever be offered to the passage of air through it in the intended
direction, excepting only by the temporary operation of a back draught,
which instantaneously closes it, and on being withdrawn leaves it free to fall
back again to its vertical position. I now insert this second box with the
valve attached to it within the first, and fasten it thereto by screws passing
through the front flanges of the two boxes. The first box is made sufficiently
deep to allow the valve on the end of the second box to work within
it without extending beyond the limits of the opening, and thus the valve
secured outside the end of the second box is made to work within the
covered and protected area of the first box. The opening presented towards
the room by the ventilator thus far fixed I then cover over either by a detached
perforated plate of any ornamental pattern, screwed or otherwise fastened on
the surface of the wall, or to the flanges of the boxes, or by a similar per-
forated plate fitting into the front opening of the second box. In either case
the effect is to screen the interior of the ventilator from view, and thereby
prevent the unceasing swinging action of the valve from being seen in the
room, and also to present a more or less artistic and ornamental object to the
eye.
Certain modifications of the arrangements here pointed out enable me to
adapt this principle of valve to chimney tops to cure smoking and prevent
down draught, and to every other description of air and smoke shaft. I do
not even in the case stated confine myself to the precise detail of proceedings
or of materials herein mentioned.