AN IMPROVED AIR AND SMOKE VALVE
Year: 1864

page_text: LEITERS PATENT to Thomas Boyle, of 31, Gray's Inn Road, London, in
the County of Middlesex, Lighting, Warming, and Ventilating Engineer,
for the Invention of AN IMPROVED AIR AND SMOKE VALVE."
PROVISIONAL SPECIFICATION left by the said Thomas Boyle at the
Office of the Commissioners of Patents, with his Petition, on the 14th
July 1864.
I, THOMAS BOYLE, of 31, Gray's Inn Road, London, in the County of
Middlesex, Lighting, Warming, 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 of a thin plate of mica suspended
vertically on its edge before an aperture for the transmission of air or smoke,
and capable of swinging freely upwards to the horizontal position, whereby it
leaves the aperture fully open, and downwards to within a few degrees of the
perpendicular, where, coming in contact with the edges of the aperture, which
are placed in a slightly sloping position from top to bottom, it there presses
with the force of its own gravity, or with that combined with the operation of
a back draught, and so closes the opening. This valve is applicable in various
positions as an outlet ventilator for air or smoke, and is adapted also to all
air and smoke shafts for the prevention of back currents and down draughts.
I will now give an example of one of its applications as an outlet ventilator.

page_text: For a chimney breast ventilator to carry off the vitiated air from a room
into the chimney flue I proceed as follows:-I make a box or case of iron or
other suitable metal similar in shape and size to the outer box or case of
the well known Arnott ventilator. -I procure a metallic plate to fit the
opening of this case or box, and I make in it one or more openings of any
convenient size or shape to form air passages, leaving the sides of the openings
to serve as flanges against which the mica covers forming the valves are
intended to rest in order to close the ventilator. I insert this plate in the box
or case in such a manner that it shall stand therein at a slight inclination
inwards from top to bottom from the perpendicular line of the face of the box,
and at the same time fill up the opening in the box or case everywhere but
at the openings in the plate itself, which now form the only passages for air
through the box. I also make provision for easily detaching this plate from
the box, and removing or replacing it at pleasure. Over each of the air
passages thus formed through the box I now suspend on the inner side of the
metallic plate a mica plate sufficiently large to lap over upon the flanges of
the openings in the metallic plate and so to be capable of closing the apertures
therein when brought into contact with them either by the force of its own
weight or that combined with the operation of a back draught. The range
of swing of the plate of mica thus suspended is limited upwards to the top
side of the box, which forms a horizontal line at a right angle to the line of the
face, and in the downward direction to the metallic plate, which, standing at
the angle above named, intercepts its complete descent to the perpendicular
position. I employ as the means of suspension of the mica valve a metallic
chain or wire. I attach this chain or wire to the valves and to the upper part of
the box in such a manner as to secure to the utmost extent two main objects,
first, such a true and perfect fitting of the edges of the valves against the
flanges of the openings as to form, on being brought into contact with them, a
practically air and dust tight union; and, secondly, the lightest and most
sensitive swinging action of the valves to and fro, whereby the apertures are
closed or opened, and the exclusion or admission of air regulated through the
ventilator. The metallic box or case thus furnished I fix in an aperture made
through the wall of the chimney breast into the chimney flue; I secure a
perforated plate in front of it as an ornamental cover and finish, and the valve
ventilator is then in a condition to operate in the transmission of air from the
room to the chimney flue, while preventing the passage of any in the contrary
direction.

page_text: SPECIFICATION filed in pursuance of the conditions of the Letters Patent,
and of an Order of the Lord Chancellor, by the said Thomas Boyle in
the Great Seal Patent Office on the 7th February 1865.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS
BOYLE, late of 31, Gray's Inn Road, London, afterwards of 243, Hampstead
Road, and now of 62, Mansfield Road, Kentish Town, in the County of
Middlesex, Lighting, Warming, and Ventilating Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Fourteenth day of July, in the year of our Lord
One thousand eight hundred and sixty-four, in the twenty-eighth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said Thomas Boyle, Her special licence that I, the said Thomas Boyle, my
executors, administrators, and assigns; or such others as 1, the said Thomas
Boyle, my executors, administrators, 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 "AN IMPROVED AIR AND SMOKE VALVE," upon
the condition (amongst others) that I, the said Thomas Boyle, 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 Seal Patent Office on or
before the Seventh day of February, One thousand eight hundred and sixty-
five.
NOW KNOW YE, that I, the said Thomas Boyle, do hereby declare the
nature of my said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement:-
The object of my Invention is to produce a self-acting valve so light and
sensitive in its action as to offer the least possible amount of obstruction to
the passage e of air through it in one direction, while effectually preventing the
possibility of any air passing through it in the contrary direction. I employ
for this purpose thin plates of mica lightly suspended over apertures formed in
a metallic plate. The metallic plate is fixed in a box on its edge not quite
vertically but at an angle varying from five to twenty degrees, according
to circumstances, from the vertical line of the face of the box, so that in
relation to this line one surface of the inclined plate will form an acute

page_text: the other surface an obtuse angle with that line. Over the apertures in the
metallic plate and on the surface thereof which forms the obtuse angle I
suspend the plates of mica, made sufficiently large to form efficient covers or
valves to the openings. Thus suspended the plates of mica when not in
nction rest against the sides of the openings and thereby keep the latter closed.
When this arrangement is complete, should air seek to pass through the
openings from the side forming the acute to that forming the obtuse angle on
which the valves are hung, it has only to lift the light plates of mica and pass
freely onwards without further obstruction; the plates of mica being free on
that side to swing upwards to the horizontal line, whereby the apertures are
left open to the full extent of their capacity. When air attempts to pass in
the contrary direction it presses against the backs of the mica valves, and this
pressure together with the force of their own specific gravity tend to close the
valves tightly against the surface of the inclined metallic plate, and effectually
prevents the passage of air through the apertures in that direction. The
qualities which render the material called mica peculiarly suitable for the
purpose to which it is here applied are, that it is light, thin, rigid, flat,
incarrodible, not sensibly affected by extremes of temperature, and practically
speaking indestructible. This valve is applicable to all outlets for air or
smoke where it is desirable to avoid retrograde currents or down draughts.
Thus chimney breast ventilators, ceiling ventilators over chandeliers or other
lights, ventilators in roofs or sides of buildings, may all be made of this
character by means of this valve.
I construct a chimney breast ventilator for carrying off the heated vitiated
air from a room into the chimney flue as follows, and the description of this
will indicate with sufficient clearness what should be done in any other position
to adapt the principle to the production of a like result. I first make an
oblong cast iron box open at top and bottom with a flange thrown outwards
on that side intended to form the face of the box. The dimensions of this box
may vary according to circumstances, but I generally make them eleven
inches long, seven and a half inches wide,) and three and a half inches deep,
measuring from out to out of the flange. The flange is made about one inch
in width, and has formed all round its inner edge a sunk groove or rebate,
about a quarter of an inch wide, and sufficiently deep to accommodate the
thickness of two pieces of metal which are intended to fit into and rest in it.
These pieces of metal are the flange of a metallic tray whose bottom forms
the plate whereon the valves are hung, and a grating intended as an orna-
mental cover and finish on the outside. The metallic tray is also made of
cast iron; it is formed with a bottom-sloping from about half an inch deep at

page_text: I suspend the plates of
one side to about one and a half at the other. This bottom being the metallic
plate on which the valves are hung is perforated with any required number of
air apertures, but generally with four, of an oblong form, over which are
suspended four corresponding plates of mica to form the covers or valves.
The slope of this bottom forms the angle of inclination at which it, together
with the valves attached to it, stand in the outer box in relation to the vertical
line of the face thereof. The sides of this tray are made of suitable dimensions
to be inserted within the box above described, and there is a flange thrown
outwards all round it to fit into and rest within the sunk groove or rebate
prepared for it in the said box, as already described.
mica on the outer surface of the bottom of this tray as follows:-I first fix two
small brass eyes in suitable positions in the metal rim over the air apertures
in the bottom plate of the tray. I then fix a similar pair of brass or other
metallic eyes in a corresponding position in the plate of mica by rivetting
thereto the flattened end of a piece of thin wire and turning the other end
into a suitable eye. I connect those two eyes by means of a small oval ring
or link cut at one side of the centre of the oval to admit the eyes and after-
wards joined. Thus prepared I insert this tray into the outer box above
described, the flange of the former resting in the sunk groove or rebate of the
latter. I place over it, resting in the same groove or rebate, the ornamental
grating or cover, both of which are fixed in their places with putty, and
when the outer box, thus furnished with its valve, tray, and cover, is inserted
in an aperture made near the ceiling in a chimney breast communicating with
a flue with the shallow part of the tray upwards and the deep part downwards,
it will be in a position to operate as an outlet ventilator in discharging the
heated air from the room while excluding all back or down draughts. I do
not confine myself to the precise details here shewn, nor to any particular
metal for any portion of the apparatus. The following is an explanation of
the Drawings.
Figure 1 is a front view of the outer box, with valve, tray, and grating fixed.
a, a, is the flange of the outer box; B, B, is the sunk groove or rebate in
which rest the valve, tray, and ornamental grating. Figure 2 is a side view
of the same box; a, a, is the flange; B, B, the sides of the box. Figure 3
is a sectional view through Figure 1. a, a, is the outer box; B, B, is the
metallic tray inserted in the outer box; c, c, c, is the inclined bottom of
same; D, D, are two of the valves suspended over the apertures and
slightly open, the arrows shewing the direction and effect of the air passing
through them; E, E, are the eyes and ring by which the valves are suspended.
Figure 4 is a front view of the surface of the metallic tray, on which the

page_text: valves are suspended. a, a, a, a, are the mica plates suspended over corre-
sponding apertures formed in the metallic plate against which they rest;
B, B, is the rim of the metallic plate; c, c, are the eyes and connecting ring
on which the valves hang.
And having now described the nature of my said Invention, and in what
manner the same is to be performed, I declare that I claim,-
First, the application of the material called mica to the production of air
and smoke valves.
:
Second, the method of adaptation of those valves herein shewn to ventilating
purposes.
In witness whereof, I, the said Thomas Boyle, have hereunto set my
hand and seal, this Seventh day of February, in the year of our
Lord One thousand eight hundred and sixty-five.
THOS. BOYLE. (L.S.)