Improvements in or connected with Ventilating Appliances for Sewers.
Year: 1894

page_text: Date of Application, 3rd Mar., 1894
Complete Specification Left, 3rd Dec., 1894-Accepted, 5th Jan.,
1895
PROVISIONAL SPECIFICATION.
Improvements in or connected with Ventilating Appliances
for Sewers.
We, JOHN CHADWICK of Petersfield, Hants, Architect and Civil Engineer and
EDWIN JAMES PRESTON of the Firm of J. Stone & Co. of Deptford in the
County of Kent, Engineers, do hereby declare the nature of this invention to be as
follows:-
:-
The object of this invention is to prevent the rise of noxious effluvia through
open street or road gratings in connection with sewers, and at the same time to
allow of the free admission of fresh air to the sewers for ventilating purposes.
It is often found with the sewer gratings now used that, although admitting fresh
air into the sewer, they also allow sewer gases to escape into the streets, which is
both dangerous and objectionable. In order to prevent this we provide sewer
gratings or manholes with a flap valve of very thin sheet metal, or of mica, or talc,
which when closed rests upon à seating formed in the body of the casting and so
hung as to open readily and allow a free passage of air into the sewer, but at once
closing, in case of any up draught from the sewer and so preventing the escape of
any noxious effluvia.
We sometimes fit one or more baffle plates or deflectors below the flap valve so
arranged that while offering little or no obstruction to the fresh air down current,
the up current of sewer gas is deflected and obstructed.
By means of the above arrangement combined with ventilating columns or shafts
or other ventilating apparatus an efficient ventilation of sewers is obtained.
In one construction of sewer grating or manhole we form the cover at one end
with grid openings and leave it solid at the other or hinge end, the space under the
grating forming a catch pit of suitable depth. A mica or other light flap valve is
provided to close an aperture in the inner end wall of the catch pit, and baffle
plates are arranged below the solid part of the cover. If the ventilating shaft
from some cause ceases to act and its suction action stops the mica valve will close,
thus preventing the escape of sewer gas; on the other hand in the normal state of
things the air entering the grating will by the suction in the ventilating shaft open
the valve and sweeping past the baffle plates carry the sewer gas with it and both
be drawn up the ventilating shaft (or it may be ejected by a fan).
Dated this 3rd day of March 1894.
JENSEN & SON,
77, Chancery Lane, London, W.C., Patent Agents.
Improvements in or connected with Ventilating Appliances
for Sewers.
We, JOHN CHADWICK of Petersfield, Hants, Architect and Civil Engineer and
EDWIN JAMES PRESTON of the Firm of J. Stone & Co. of Deptford in the
County of Kent Engineers do hereby declare the nature of this invention and in

page_text: what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement :-
The object of this invention is to prevent the rise of noxious effluvia through
open street or road gratings in connection with sewers, and at the same time to
admit of the free admission of fresh air to the sewers for ventilating purposes.
It is often found with the sewer gratings now used that, although admitting fresh
air into the sewer, they also allow sewer gases to escape into the streets which is
both dangerous and objectionable.
In order to prevent this we provide sewer gratings or manholes with a flap valve
of very thin sheet material such for instance as metal mica or talc, which when
closed rests upon a seating formed in the body of the casting, and is so hung as to
open readily and allow a free passage of air into the sewer, but at once closing in
case of any up draught from the sewer and so preventing the escape of any noxious
effluvia.
In the accompanying drawings we have shewn vertical sections of various forms
of road boxes, gulleys and the like so constructed.
In the ventilating road box E Figure 1 the flap valve A is fitted to the door or
cover C and resting freely on a seating_round an aperture between the dirt box B
and the duct D leading to the sewer. The cover C is at one end over the dirt box
formed with grid openings and left solid at the other or hinge end. When the
pressure of the outer air exceeds the pressure in the sewer to the least degree or
when a ventilating shaft is in action the light flap valve A will be open, but in case
of any up draught from the sewer the valve will readily close and prevent the
escape of sewer gas.
In the trapped gulley box Figure 2, the valve seat is formed wholly on a
downwardly projecting frame on the cover C and the body of the casting E may
be formed with ledges E¹ for the said frame to rest against.
Figure 3 shews a sewer manhole casting E with the valve A seating itself against
a downward projection on the door C and on an upstanding lateral ledge on the
loose dirt box B¹.
In the stable or yard gulley Figure 4 the valve A is hung on the outer side of
the body or casting E towards the outlet D to the sewer.
We sometimes fix one or more baffle plates or deflectors below the flap valve so
arranged that while offering little or no obstruction to the fresh air down current,
the up current of sewer gas is deflected and obstructed. By this means combined
with ventilating columns or shafts or other ventilating apparatus an efficient
ventilation of sewers is obtained.
Figure 5 shews one construction of sewer grating or manhole where the cover C
similar to Figure 1 is formed at one end with grid openings and left solid at the
other or hinge end, the space B under the grating forming a catch pit or dirt box
of suitable depth. The light flap valve A is hung as in Figure 1. Baffle
plates G G are arranged below the solid part of the cover. If the ventilating
shaft from some cause ceases to act and its suction action stops, the valve A will
close thus preventing the escape of sewer gas, on the other hand in the normal
state of things the air entering the grating will by the suction in the ventilating
shaft open the valve A and sweeping past the baffle plates G G' carry the sewer
gas with it and both be drawn up the ventilating shaft (or it may be ejected by
a fan).
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that we do
not claim the adaptation of light flap valves as before described to sewer
ventilators fitted above the ground, or of such flaps fitted to horizontal pipes
or channels in connection with sewers underground, but what we do claim is :-
-
1. The combination with sewer ventilating road boxes, manhole covers gulleys
and the like which are fitted flush with the ground of a light flap valve which is so
hung that it is normally open under the influence of down draught through the

page_text: cover opening or openings but closes automatically in case of any up draught
substantially as set forth.
2. In combination with the light flap valve A the baffle plates G G¹ substantially
as and for the purpose set forth.
3. The construction of sewer ventilating road boxes, manholes and gulleys shewn
in the drawings.
Dated this 3rd day of December 1894.
JENSEN & SON,
77, Chancery Lane, London, W.C., Patent Agents.