Improved Chimney Top or Cowl, Applicable also as a Ventilator.
Year: 1889

page_text: Date of Application, 5th Mar., 1889
Complete Specification Left, 30th Nov., 1889-Accepted, 1st Feb., 1890
PROVISIONAL SPECIFICATION.
Improved Chimney Top or Cowl, Applicable also as a Ventilator.
I, HERBERT HELLEWELL, offices 4, North Corridor, Royal Exchange, Manchester,
in the County of Lancaster, Engineer, do hereby declare the nature of this invention
to be as follows:-
This invention is designed chiefly for application to the tops of chimney stacks to
prevent down draught, but may also be used as an exhaust ventilator.
It consists essentially in constructing a cowl or ventilator with exit passages placed
at right angles to each other formed by placing a conical or tapering deflector therein
with a hood or other cover to form the outer passages so that any current of air
striking the ventilator will be conducted across the mouth of the internal passages at
right angles and this by suction create a current through.
or
I construct the top or cowl of any suitable material such as metal (sheet or cast)
terra-cotta, earthenware, or the like, and of any required shape cylindrical,
rectangular, polygonal or otherwise, which will be suitable for the position in which
it is to be placed. At the exit end I place a deflector preferably in the form of a
double cone, one apex extending downwards into the mouth of the top or cowl and
the other extending upwards therefrom. Each cone is so formed that the sides
approach each other forming a right angle at the apex and the sides of the two cones
also join at a right angle. Thus the sides of one cone are equal in length to the sides
of the other and the distance from one apex to the other apex is equal to the
diameter of the base. For cylindrical chimney tops or cowls I prefer to make the
deflector conical as described, but for rectangular or polygonal tops or where it is
required to deflect the smoke in certain directions only, so as not to interfere with the
draught of other chimneys the deflector may be made pyramidal with two, four, six,
ow more sides, rectangular at the apex of each and at the junction of the sides of the
deflected to such an angle as to be parallel with the sides of the deflector, projecting
into it, the passage for the smoke lying between the two. The outer edge of the
wall is extended downwards for a short distance in a line with the upper edge of the
deflector having the exit passage at right angles thereto. A hood or bonnet covers
the deflector and extends down below the deflector. This hood is placed parallel
with the upper sides of the deflector and forms a passage or chamber around the exit
end of the top or cowl at right angles to the exit passages therein. The bonnet is
open both top and bottom. Where the direction of the smoke is to be controlled the
bonnet may
be constructed to form a number of chambers of tubular or other form
or separate tubes in the form of arms may be used, each in communication with the
exit passages and at right angles thereto. As the passages around or in communi-
cation with the internal exit passages are placed at right angles thereto I consider
that any current of wind blowing through them in either direction across the exit
passages will have the effect of causing an upward current and of carrying the
smoke with it, and that-from whatever the direction the wind may be any wind
striking against the cowl will, by suction, exhaust or create a current upwards
through it.
Although chiefly described as a chimney top or cowl the apparatus may be
applied to railway carriages, buildings, or other structures as an exhaust ventilator.
Dated this 4th day of March 1889.

page_text: COMPLETE SPECIFICATION.
Improved Chimney Top or Cowl, Applicable also as a Ventilator.
I, HERBERT HELLEWELL, offices 4, North Corridor, Royal Exchange, Manchester,
in the County of Lancaster, 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 invention is designed chiefly for application to the top of chimney stacks to
prevent down draught therein and also to be used as an exhaust ventilator for rooms
and other limited or confined spaces.
It consists essentially in constructing a cowl or ventilator with exit passages
placed at right angles to each other formed by placing a conical or tapering deflector
therein with a hood or other cover to form the outer passages, so that any current of
air striking the ventilator will be conducted across the mouth of the internal passages
at right angles and thus by suction create a current through.
It will be fully described with reference to the accompanying drawings.
Fig. 1 is a front elevation of cowl of cylindrical form.
Fig. 2 sectional elevation of same.
Fig. 3 front elevation of rectangular form.
Fig. 4 sectional elevation of same.
Fig. 5 transverse sectional elevation of same.
Fig. 6 plan of same..
Fig. 7 front elevation of cylindrical form as a ventilator to be applied to railway
carriage roofs.
Fig. 8 sectional elevation of same.
The top or cowl may be constructed of any suitable material preferably sheet
inetal though terra-cotta, earthenware or the like may be employed and it may be of
any desired shape such as cylindrical, rectangular, polygonal, or otherwise as may be
found most serviceable in the position in which it is to be placed.
The top or exit end of the shaft A. is formed with a top rim a inclined outward and
in the end of the shaft A is placed a deflector B. conically tapered or inclined in two
directions which for cylindrical cowls will be in the form of a double cone. One
end. or apex of the deflector B projects downwards into the mouth of the cowl
and the other extends upwards therefrom. For the cylindrical cowls cach
deflector is formed of a double cone so constructed that the sides approach each
other, forming a right angle at the apex, and the sides of the two cones also join at a
right angle. Thus the sides of one cone are equal in length to the sides of the
other and the distance from one apex to the other apex is equal to the diameter of
the base.
At the exit end of the cowl the deflected or inclined rim a is formed with the
walls deflected to such an angle as to be parallel with the sides of the deflector B
which project into it, the passage for the smoke or air lying between the two. The
outer edge of the wall is extended downwards for a short distance forming a second
rim a in a line with the upper edge of the deflector, having the exit passage at right
angles thereto. A hood or bonnet C covers the deflector and extends down below the
deflector. The hood' is constructed with a vertical top and. inclined or tapering
sides c parallel with the upper sides of the deflector B. open both top and bottom.
The hood C forms a passage or chamber above or around the deflector B at the top
of the cowl at right angles to the exit passages. The deflector B and hood' Care
secured in position by the metal pieces or brackets d and'e.
The exit passages are thus formed at the top of the cowl' by the deflector B'and
hood C the passage D being between the lower cone of the deflector and the outward
inclined top or riin a of the shaft A and the passage E being between the upper
cone of the deflector and the second ring a¹ on the one side and the inclined or
tapering sides c of the hood C on the other. The passage E crosses the exit end of
the passage D at right angles thereto. A current of wind blowing in either direction

page_text: through the passage E across the exit passage D will have the effect of causing an
upward current in the shaft A drawing up the smoke or foul air with it.
In figs. 1-2-7 and 8 the cowl or ventilator is shown cylindrical with conical
deflector the tops may however in plan be made triangular rectangular or polygonal in
which case the deflector will be made pyramidal top and bottom with three four five,
six, or more sides; in each case the angle formed by the opposite sides at the apex and
at the junction of the top and bottom parts will be a right angle or approximating to
a right angle.
In cases where it is desired to deflect the smoke or current in certain directions
only so as not to interfere with the draught of other chimneys the cowl may be made
with openings on one, two, or three sides only.
Referring to Figs. 3 to 6 such an arrangement is shown in which the exit openings
are at two sides only. The arrangement of the several parts is substantially the
same as that hereinbefore described. The shaft A is rectangular and is fitted with a
deflector B in the form of a cube with one edge uppermost and presenting a flat side
to the front and back. Instead of a continuous hood the exit passages E are formed
of the arms C and the passages D are formed by the sides of the cubical deflector B.
In this form the cowl will be found convenient for chimney stacks where a number
will have to be placed close together. Where one opening only is required the cowl
could be made similar to this divided on the line .c. y. fig. 4.
Referring to figs. 7 and 8. A ventilator is shown constructed similar to the cowl
in Figs. 1 & 2, designed to be applied to the roof of railway carriages. The
ventilator may also be applied to other structures or buildings the base being merely
altered to correspond with the fixture to which it is to be attached.
Having now particularly described and ascertained tho nature of the said inven-
tion and in what manner the same is to be performed I declare that what
I claim is :-
1. A chimney cowl or ventilator having exit passages placed at right angles to
each other formed by a conical or tapering deflector affixed in the mouth of a shaft
in combination with a hood or cover substantially as described.
2. A chimney cowl or ventilator having a double conical pyramidal or tapering
deflector, interposed between the top of the cowl and a hood or cover in such a
way as to form exit passages one crossing the other at right angles substantially as
described.
Dated this 23rd day of November 1889
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WM. P. THOMPSON & Co.,
Manchester, Liverpool, and London, Patent Agents.