Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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SEWER OVERFLOW RELIEF DEVICE
FIELD OF THE INVENTION
The present invention relates to a device for providing sewer overflow relief
arrangements and to venting of sewers. The invention is described herein in
relation
to domestic plumbing but is not limited to that application only.
BACKGROUND OF THE INVENTION
Waste water is carried away from buildings and roads via two different
systems. The
first is via stormwater drains and channels, which typically discharge
directly to a
natural body of water such as a river, estuary or sea. While some rubbish
carried
from stormwater may be filtered from the flow by appropriate screens or
grates, the
water itself is not treated before discharge, as it is generally freshwater
run-off from
rainfall or storms. The second system is the sewage system, and water or
sewage
discharged to the sewage system must be carefully treated by appropriate
processes
before the treated water can be discharged into the environment. Such
treatment is
expensive.
The connection of a house or building to the general sewage system includes
provision for dealing with local sewage blockages or pressure problems. Rather
than
having a situation where sewage backs up through an outlet in the home (for
example, the toilet), an overflow relief gully is provided outside, adjacent
the home.
This ensures that in the event of a sewage overflow, the overflow does not
incur
inside the home. Typically the overflow relief gully is a grate over a pit,
connected to
the building's sewage system by a sewer overflow relief pipe having a water
seal
created by a 'water trap' or 'U-bend' which prevents egress of sewer gas. This
pipe is
run as an extension from the sewage pipes under the house and typically the
sink
waste water is run to the overflow relief gully in order to maintain the water
seal. A bib
tap is also provided to help maintain the water seal.
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It has become a common practice for builders and landscapers to channel
stormwater run-offs into the overflow relief gully, instead of to the
stormwater system.
This is because the overflow relief gully is typically conveniently located
near the
home (in order to minimise the length of the extension and distance to run the
sink
waste water), and hence is located near surfaces such as concreted driveways
and
the like, from which water runs off. The driveways and the like are
deliberately built
with a gradient directing the run-off water to the overflow relief gully.
Also, guttering
down pipes can also be run to the overflow relief gully. This practice is very
undesirable, as it increases significantly the volume of sewage that needs to
be
treated, and hence the costs associated with carrying the volume of sewage to
a
treatment plant, the number of treatment plants required, and the cost of
actually
treating the sewage. It is therefore desirable to reduce the volume of sewage
requiring treatment.
It is an object of the invention to provide an improved overflow relief
device, or at
least to provide an alternative in the marketplace.
SUMMARY OF THE INVENTION
One aspect of the invention provides a sewer overflow relief device co-
operable with
a tube in communication with a sewer so as to be lifted from the tube by
rising liquid
to provide overflow relief and including structure defining a flow path along
which air
entering the sewer moves upwardly past a valve element configured to prevent
gas
escaping the sewer.
The device is preferably receivable within the tube.
An annular seal, such as an 0-ring, may be provided for engaging the tube.
Preferably the device is configured to float on the rising liquid.
The device may include a float member.
Preferred forms of the device impede water entering the sewer.
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Another aspect of the invention provides the device and the tube.
Also disclosed is a sewer overflow relief device for mounting at a top end of
a sewer
overflow relief pipe, the device including:
a top cover having at least one outside air intake;
- air flow control means for controlling the flow of outside air into the
sewer
overflow relief pipe;
wherein, in use, the device impedes outside water entering the sewer and the
device
may be ejected from the sewer overflow relief pipe by sewage pressure pushing
against the device, thereby allowing the sewer overflow relief pipe to
overflow.
Preferably, the air flow control means include:
a one-way air valve having an upstream side in fluid connection with the at
least one outside air intake, and having a downstream side in fluid connection
with
the sewer overflow relief pipe;
the valve oriented, in use, with the upstream side at a lower level than the
downstream side; the valve operable to allow passage of air when pressure on
the
downstream side is lower than on the upstream side, whereby outside air is
admitted
into the sewer overflow relief pipe.
Advantageously, this prevents egress of sewer gas, as sewer gas tends to rise
and
therefore is less likely to escape in a downward direction when the valve is
in an
open position.
Preferably, the at least one outside air intake is, in use, located on a
raised portion of
the device.
In a preferred embodiment, the sewer overflow relief device further includes:
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a body of circular cross section for insertion into the top end of the sewer
overflow relief pipe, the side walls of the body in a close fitting
arrangement with the
internal wall of the top end of the sewer overflow relief pipe thereby
preventing
egress of sewer gas;
the top cover being fixed to the body and having the same diameter as the
outer
diameter of the top end of the sewer overflow relief pipe, whereby the device
is
difficult to manually remove from the sewer overflow relief pipe.
If desired, the body and the 'pipe' into which the body is inserted could have
any
cross-sectional shape, such as a square or other polygon, provided a close fit
is
obtained. Optionally, a pipe end extension or receiving housing can be fitted
to
extend the pipe and to receive the device. The end extension or receiving
housing
may be of different cross-sectional area or shape to the rest of the pipe.
In another preferred embodiment, the sewer overflow relief device further
includes:
a float for engaging against the device;
wherein, in use, the device may be ejected from the sewer overflow relief pipe
by
sewage pressure pushing against the float. This provides for an even force to
be
applied to the device, ensuring that it does not jam or wedge within the pipe.
The size
(volume) of the float can also be selected such that the device is ejected
from the
pipe earlier than would otherwise occur.
Advantageously, the disclosed device according to the first aspect of the
present
invention will impede stormwater from entering the sewer via the sewer
overflow
relief pipe.
Another advantage of this device is that local venting of the sewer may be
achieved,
reducing the need for alternative venting arrangements. When waste water is
flushed
down the drains, ventilation must be provided to allow the flowing waste water
to
displace the sewer gas in the drain and then the vacuum which would otherwise
form
as the waste water flows down the drain. "Neutral" air pressure is required in
drains,
CA 02678710 2012-07-24
in order to ensure that the gravity operated system functions correctly. As
the waste
water passes the sewer overflow relief pipe junction with the sewer drain, air
may be
replenished into the sewer via the one-way valve, which is operated to
automatically
open when a low pressure or partial vacuum is present in the sewer overflow
relief
5 pipe, drawing air in through the outside air intake. The valve element
opens a short
distance to allow air to enter the sewer but to impede the flow of water along
the
same flow path.
Yet another advantage of the disclosed device is that it avoids the need to
provide a
separate water trap or U-bend to prevent egress of sewer gas, which is both
unpleasant to smell and hazardous. The sewer overflow relief pipe may be
installed
as a simple vertical section of pipe, and its end simply fitted with an
overflow relief
device. This reduces both materials and labour involved in construction. It is
not
necessary to provide an extension from the pipes running under the house to
adjacent the external wall. The overflow relief pipe may be located near the
property
boundary, and simply be a vertical extension running from the pipe connecting
the
house to the public sewer. Nor is it necessary to run the sink waste water or
provide
a bib tap to the overflow relief gully. Furthermore, by locating the overflow
relief pipe
remote from the external wall of the house, the temptation for builders or
landscapers
to deliberately channel stormwater or other run-offs to the overflow relief
gully is
much reduced. As mentioned above, a pipe extension or receiving housing can be
fitted to extend the overflow relief pipe, or the pipe may simply end without
an
extension or other fitting.
As stormwater will not drain effectively via the sewer when the sewer overflow
relief
pipe is fitted with the device, and as the device is tamper resistant (and
also
necessary to prevent sewer gas egress and smells), builders, landscapers and
the
like will be motivated to ensure stormwater run-off is appropriately directed
to
stormwater drainage points (typically near the boundary of a property).
Also disclosed is a sewer overflow relief device for mounting at a top end of
a sewer
overflow relief pipe, the device including:
a top cover; and
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wherein, in use, the device impedes outside water entering the sewer and the
device
may be ejected from the sewer overflow relief pipe by sewage pressure pushing
against the device, thereby allowing the sewer overflow relief pipe to
overflow.
Preferred forms of the device are useful for retro-fitting situations, where
venting of
the sewer is provided by existing arrangements, and sewer gas egress is
prevented
by existing water traps or U-bends.
BRIEF DESCRIPTION OF THE DRAWINGS
Other features and advantages of one or more preferred embodiments of the
present
invention will be readily apparent to one of ordinary skill in the art from
the following
written description with reference to and, used in conjunction with, the
accompanying
drawings, in which:
Figure 1 shows a top view of a device according to a preferred embodiment of
the
present invention;
Figure 2 shows a cross-sectional side view of a device according to the
embodiment
of Figure 1, along the line A-A;
Figure 3 shows another top view of a device according to the embodiment of
Figure 1
positioned in a pipe;
Figure 4 shows a cross-sectional side view of a device according to the
embodiment
of Figure 3, along the line B-B;
Figure 5 shows a sectioned top perspective view of a device according to
another
embodiment of the invention, along the line A-A;
Figure 6 shows a schematic plan view of a house having a sewage system
incorporating a device according to an embodiment of the invention; and
Figure 7 shows a schematic plan view of a house having a traditional overflow
relief
gully.
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,
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DESCRIPTION OF PREFERRED EMBODIMENT
Figure 1 is a top view of a device according to a preferred embodiment of the
present
invention together with a pipe end extension or receiving housing. It shows a
top
cover 30 having an outer diameter 34. The top cover 30 has four outside air
intakes
36. As may be seen in Figure 2, (which is a cross-sectional view of the
embodiment
taken along the section line A-A as shown in Figure 1) the top cover 30 has an
upper
surface which is a dome 32. The device further includes a body or housing 20,
an
insert 60 and air flow control means, being a one way valve 72 having an outer
ring
73. A float 56 also resides within the housing 20.
The housing 20, insert 60 and top cover 30 are assembled together in order to
form
an air path through which outside air is drawn through outside air intake 36,
through
conduit 64 of insert 60 into lower chamber 80 and then to sub-chamber 82.
Lower
chamber 80 is formed by housing 20 and insert 60. The path taken by air is
shown by
the heavy black arrows. When one-way valve 72 is in a raised position (not
shown),
air passes from lower chamber 80 through valve 72 into upper chamber 90. As
shown in Figure 2, the housing 20 includes support members 21 which support
the
insert 60. These support members 21 define a sub-chamber 82 of lower chamber
80.
The valve 72 is only raised when the air pressure in upper chamber 90 is lower
than
the pressure in lower chamber 80. As may be seen in Figure 4, (which is a
cross-
sectional view of the embodiment taken along the section line B-B as shown in
Figure
3), the device 10 is installed at the end of pipe 50. The device may be
installed
directly in the pipe (not shown) or be received by a pipe end extension 120,
which
extension has a tubular form. Air passes from upper chamber 90 through housing
conduit 16 to the sewer pipe 50- chamber 90 is in fluid communication with the
sewer. This arrangement allows for the venting of the sewer overflow relief
pipe 50
but prevents egress of sewer gas from the sewer through the end of the pipe
50,
which is wholly blocked by the sewer overflow relief device 10. It is
therefore not
necessary to provide a separate water seal such as a 'water trap' or 'U-bend'.
Air can only pass in one direction through the sewer overflow relief device 10
- that is
outside air may pass into the sewer.
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The lower chamber 80, which is on the upstream side of one-way valve 72, is in
fluid
communication with outside air, via outside air intake 36 and conduit 64. By
relying
upon negative sewer pressure to raise one-way valve 72 in order to admit air
into
upper chamber 90 and, where neutral pressure is obtained, relying upon gravity
to
close one-way valve 72, the valve 72 only lifts a small distance such that the
admittance of any water that may be present into the sewer is severely
restricted.
One-way valve 72 is desirably manufactured from a material heavier than water.
Therefore, if chamber 80 is filled with water, the valve 72 is not raised by
normal
water pressure - only by negative pressure in chamber 90.
Stormwater and other water is further deterred from entering the device 10 as
the
outside air intake holes 36 are raised by being situated part way up dome 32.
Where
water does enter through these holes, it may pool in lower chamber 80 and on
relatively rare occasions be passed through to chamber 90 (as described
above).
However, this is a very small volume of water when compared to the volume of
water
typically passed into the sewer system from stormwater run off.
An optional pipe end extension or receiving housing 120 may be provided at the
end
of pipe 50. The device 10 is received by or fits inside extension/housing 120
(or
optionally may be integrally formed) and the raised dome section 122 of the
housing
120, which extends above the local ground level (or bottom of a pit) further
prevents
stormwater from pooling near or entering intake holes 36.
The extension/housing 120 may also serve as an 'adaptor' for the device 10,
allowing
retrofitting of the device 10 into finishing collars (also known as mound
collars) (not
shown) installed at pipe ends (usually for supporting grates). It can be used
with
terracotta, PVC and iron finishing collars.
The extension/housing 120 has the 'same' internal diameter as pipe 50 and is
positioned to rest upon the end of the pipe 50. Preferably, the
extension/housing 120
has a resilient structure or is of resilient material, such that it may be
readily installed
in a retrofit situation and allows for ease of insertion of the device.
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The extension/housing 120 shown in Figure 4 includes an angled outer rim 124
(forming an 'arrow' in cross-section) which may be useful in a retrofit
situation as it
assists in guiding for installation and increases the resilient flexibility in
this area. An
0-ring may be provided to rest on the base of the 'arrow' to seal to a
finishing collar.
In the event that the sewer pressure builds such that the sewer overflow
relief device
is required to operate by overflowing, in order to prevent overflow at a
location inside
the house, the float 56 pushes against housing 20 thereby causing the entire
sewer
overflow relief device 10 to pop out or eject from the sewer overflow relief
pipe 50 (or
from extension/housing 120). This allows the sewer to overflow as necessary
from
the overflow relief pipe 50. Once the situation has been corrected or
resolved, the
overflow relief device 10 may be simply re-installed into the pipe 50.
As the top cover 30 has an outer diameter 34 which is the same or lesser
diameter
than the outer diameter of pipe 50 (the embodiment of Figure 4 has outer
diameter
34 the 'same' as the inner diameter of pipe end extension 120 of pipe 50), it
is very
difficult for the general public or indeed a workman to tamper with the sewer
overflow
relief device 10. A special tool may be required to remove the device -
potentially
being inserted through an outside air intake hole 36. A further motivation for
avoidance of tampering is the fact that the sewer overflow relief pipe 50 does
not
need to have been provided with a water seal and hence removal of the overflow
relief device 10 will result in egress of sewer gas -which both smells and is
hazardous. Therefore, attempts to alter the device or force it into a
permanently
'open' valve position, to allow stormwater to freely drain to the sewer, are
unlikely.
As may be seen in Figures 2, 4 and 5, the various parts of the sewer overflow
relief
device 10 according to embodiments of the invention may be fixed and sealed
together by provision of sealing 0-rings 38 and 42, which seal the top cover
30 to the
insert 60 and housing 20. The device 10 is closely fitted inside
extension/housing 120
or pipe 50, (once installed). The outer diameter of housing or body 20 is
closely
matched to the inner diameter of the receiving housing 120 or pipe 50.
Optional holes
(not shown) in the wall 22 may enable both a saving of material and a degree
of
resilient movement in the housing 20, to enable ease of installation.
Depending on
the characteristics of the material selected, the holes may, or not, be
appropriate in
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some embodiments. Preferably the device is manufactured from PVC. 0-ring 28
seals the sewer overflow relief device 10 to the receiving housing 120 or to
the sewer
overflow relief pipe 50. The insert 60 may be affixed to top cover 30 via
screws
engaged through screw holes 46, 66, 26. The distance through which one-way
valve
5 72 may travel is regulated by valve stop 44 provided on top cover 30. One-
way valve
72 rests in its closed or lowered position upon insert 60, however, the
precise
arrangement may be varied and it could also rest upon the housing. In a less
preferred embodiment (not shown) the device is fitted outside the pipe 50
rather than
inside and alternative tamper proof features may be provided.
10 As is shown in Figure 6 which is a schematic plan view, the present
invention allows
for an arrangement in which (when compared to Figure 7, a schematic plan view
of
prior art arrangements) an extension pipe 112 and overflow relief gully 110
may be
omitted. Sewer main 100 is connected at sewer connection point 104 to a
private
property 102 having a building 106. A venting arrangement 108 is provided at
the
remote end of the building 106 (the additional venting provided by the present
invention provides localised venting). The overflow relief pipe may be
provided as a
vertical pipe at the sewer connection point 104, thereby further removing the
temptation for stormwater to be drained towards it as it is remote from the
house and
from concreted driveways, paths, guttering down pipes and the like.
The scope of the claims should not be limited by the preferred embodiments set
forth
in the examples, but should be given the broadest interpretation consistent
with the
description as a whole.
