Improvements in Cowls or Ventilators.
Year: 1890

page_text: Date of Application, 16th Oct., 1890-Accepted, 22nd Nov., 1890
COME DEID ST DUITIATION.
Improvements in Cowls or Ventilators.
I, JOHN JONES of 40 Sidney Street, Chelsea, in the County of Middlesex, Builder
and Contractor, 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 :-
This invention relates to cowls or heads applicable for chimneys or ventilators
for the purpose especially of preventing down-draught though it may also have
the effect of creating an up-draught.
and
The invention will be best understood from the accompanying drawings, in which
Fig. 1 is a vertical section of a ventilator constructed according to this invention,
Fig. 2 is a view of the ventilator the left hand half in plan and the right hand half
in section upon the line 2-2 of Figure 1.
Like letters indicate like parts in the drawings.
A is the shaft or body by which it is connected to the chimney, roof, or other
support, and B is a tapering continuation of A terminating in the interior of the
circular conical expansion chamber C as is clearly indicated in the drawing. Upon
the top of B is the circular collar or lip D.
Above the tapered or conical tube B is the circular expansion chamber C whose
walls may also be extended at C¹ so as to form a circular collar or lip as in the former
case. The bottom C of the expansion chamber is preferably dished as shown and
so arranged in conjunction with the collar D that in case of back draught the air,
smoke etc. forced into the chamber would collect in its largest part near the bottom
and be directed by the dished bottom towards the space under the collar D which
would thus have the effect of preventing the draught from entering the restricted
opening into B. At the open top of C is a short cylindrical tube E carrying at
its upper end an external collar F similar to D.
The general operation of this cowl or ventilator may be described as follows:-
The up-cast of air or smoke would be as usual but in case of atmospheric
disturbances the air forced against this cowl would be in the first place unlikely
to enter it on account of the peculiar external construction. Suppose for example an
external up-draught would meet the exterior of the dished bottom C and be deflected
against the collar or lip (which to a large extent would prevent it proceeding any
further in the same direction. Should any of it however pass the collar (and havo
a tendency inwards it would be checked by the top collar F which would have the
effect of throwing it again outwards when it would not reach the central vertical line
of the cowl until too high to enter the interior. Should however any down-draught
be produced the air entering the tube E would pass into the expansion chamber C
which as indicated in the drawings is made very large in proportion to the small
entrance into B and thus between the large expansion chamber, the small orifice
of B and the collar D it becomes almost impossible for any down-draught to pass
into B or A.
These cowls may be made in any size and of any suitable material preferably zinc
or galvanized iron, and while I prefer to make them circular I do not bind myself to
this form only. The disbed bottom Cof the expansion chamber is also preferred
to a flat one, partly on account of the direction it is calculated to impart to the air
inside and partly as it provides in combination with the collar C₁ a convenient
receptacle or catch chamber C³ for the upwardly proceeding draught; the flat bottom
however can be employed if required. The cylindrical tube E with its collar F is
also a preferred construction but it will be understood that the collar F can be placed
directly on the top of the cone C without the intervention of the tube E; it is

page_text: preferred however to employ the tube E as greater space and more of a catch
chamber is thus provided at F¹ between the cone C the tube E and the collar.
If desired I may have in the dished bottom (2 one or more small holes to permit
of the passage of moisture which may collect in the chamber C; sometimes rain is
driven into it and it is then desirable to provide means for disposing of it. These
holes however should be small so as not in any way to interfere with the action
of the cowl. If desired a cap of any ordinary construction may be added to this cowl
above the collar F¹.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, I wish it to be understood that
I am aware of my previous Patent No. 20554 of 1889 and do not separately claim
anything therein set forth, but what I claim is :-
1. The combination and arrangement of parts constituting the complete cowl
substantially as described and illustrated in the accompanying drawings.
2. In a cowl or ventilator the combination with a tapered tube such as B and
collar D of an expansion chamber such as C substantially as described and illustrated
in the accompanying drawings.
3. In a cowl or ventilator an expansion chamber such as C having conical walls a
dished bottom such as C² and collar such as C substantially as described and
illustrated in the accompanying drawings.
4. In a cowl or ventilator the employment of an internal collar or lip such as D
substantially as described and illustrated in the accompanying drawings.
Dated this 16th day of October 1890.
W. P. THOMPSON & BOULT,
Agents for the Applicant.