Note: Descriptions are shown in the official language in which they were submitted.
CA 02420444 2009-12-15
FIELD OF THE INVENTION
This invention relates to inspection chambers for use in sewers, to an
inspection chamber
with an integral back-flow prevention valve, and to a tool for installing a
back-flow-prevention
valve in an installed inspection chamber.
BACKGROUND OF THE INVENTION
Inspection chambers are required to be provided in sanitary sewer systems in
many
jurisdictions. An inspection chamber is typically installed where the sanitary
sewer outlet from
a building joins the sewer main of a municipal sewer system. Inspection
chambers serve two
main purposes. First, during construction of a new sewage system, an
inspection chamber can
be used as a location for a plug to seal the passage between the new sewage
system and the
sewer main until the new sewage system has been tested and approved. After
testing and
approval, the plug can be removed by hooking a handle on the plug and pulling
the plug out of
the inspection chamber. Second, an inspection chamber can be used as a point
of access to
remove blockages from a sewer system.
An inspection chamber is typically installed at least several feet
underground. The
inspection chamber typically has interior dimensions slightly larger than the
diameter of the
sewage pipe in which it is installed. Typical diameters of sewage pipes from
residential or light
industrial buildings are in the range of 4 inches to 6 inches. A generally
vertical access pipe,
which is typically somewhat larger in diameter than the sewage pipe, extends
from the
inspection chamber to the surface where it is sealed with a cap. The access
pipe is typically
several feet long. Typical diameters of access pipes are in the range of about
6 inches to 10
inches. After an inspection chamber has been installed it is very difficult to
gain access to the
inside of the inspection chamber.
It is generally desirable to provide a back-flow valve in the sewage pipe. A
back-flow
valve serves to prevent sewage from backing up from the municipal sewer into a
building. The
back-flow valve also serves to prevent vermin, such as rats, from entering a
building from the
municipal sewer lines through the building's sewage pipe. A problem with back-
flow valves
is that they are installed in the sewage line, which is several feet
underground. If the back-flow
valve malfunctions or if debris gets stuck in the back-flow valve then it is
generally necessary
to dig down to the back-flow valve to replace or repair it. This is both
disruptive and
expensive.
The inventor has recognized a need for an inspection chamber which can be
plugged,
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as described above, during testing and approval of a sewage system and has an
integral
back-flow valve. It has not been previously practical to provide such an
inspection chamber
because any pre-instal led back-flow valve would interfere with insertion or
removal of a plug.
After the plug has been removed, the inspection chamber is several feet down
the access pipe
and is not easily accessible.
SUMMARY OF THE INVENTION
This invention provides an inspection chamber with an integrated back-flow
prevention
valve. One aspect of the invention provides an inspection chamber for a sewer
line. The
inspection chamber comprises: a housing having inlet, outlet and access ports
for connecting
inlet, outlet and access pipes respectively, and a flapper valve in the
housing. The access port
is located in an upper portion of the housing and is oriented generally
perpendicularly to each
of the inlet and outlet ports. The flapper valve comprises: a valve member
comprising a
transverse pin, a flap member attached to the pin and a handle member
projecting from the flap
member; a clip for receiving the pin of the valve member and detachably
retaining the pin in
pivotal relation to the housing, the clip located below the access port and
above the inlet port
and oriented to receive the pin from a direction of the access port; and a
sealing surface inside
the housing around the inlet port. When the pin of the valve member is
received in the clip, the
flap member bears against the sealing surface and is capable of blocking a
flow of sewage from
the outlet port through the inspection chamber and the inlet port, and the
valve member can
pivot about the pin to permit sewage to flow from the inlet port, through the
inspection chamber
and out the outlet port.
A second aspect of the invention provides a sewer system comprising a sewage
pipe
extending from a building to a municipal sewer and an inspection chamber
connected in the
sewage pipe at an underground location between the building and the municipal
sewer. The
inspection chamber comprises: a housing having an inlet port connected to a
portion of the
sewage pipe extending to the building, an outlet port connected to a portion
of the sewage outlet
pipe extending to the sewer, an access port connected to an access pipe
extending generally
vertically to an unburied location, the access port in an upper portion of the
housing and
oriented generally perpendicularly to each of the inlet and outlet ports; and
a flapper valve in
the housing. The flapper valve comprises: a valve member comprising a
transverse pin, a flap
member attached to the pin and a handle member projecting from the flap
member; a clip for
receiving the pin of the valve member and detachably retaining the pin in
pivotal relation to the
housing, the clip located below the access port and above the inlet port and
oriented to receive
the pin from a direction of the access port; and a sealing surface inside the
housing around the
inlet port. When the pin of the valve member is received in the clip, the flap
member bears
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against the sealing surface and is capable of blocking a flow of sewage from
the outlet port
through the inspection chamber and out the inlet port, and the valve member
can pivot about
the pin to permit sewage to flow from the inlet port, through the inspection
chamber and out
the outlet port. A sealing lid is provided at the top end of the access pipe.
The invention also provides a method for installing a flap valve member in an
inspection
chamber in a sewer system. The method comprises the steps of providing a valve
member
comprising a transverse pin, a flap member attached to the pin and a handle
member projecting
from the flap member; attaching the valve member to a holder on an
installation tool
comprising an elongated shaft, the holder comprising means for holding the
handle member and
a tab adjacent the pin; lowering the valve member through an access port on
the inspection
chamber with the installation tool; aligning the pin with a clip in the
inspection chamber;
hammering the installation tool downwardly to cause the tab to press the pin
into engagement
in the clip; and removing the installation tool.
In a preferred embodiment, the step of attaching the valve member to a holder
on an
installation tool comprises inserting the handle member between a pair of
fingers biased toward
each other. Preferably the step of hammering the installation tool downwardly
comprises
sliding a weight upwardly along the shaft of the installation tool and
dropping the weight onto
a stop on the shaft. The method may further include the step of removing the
valve member
from the inspection chamber by the steps of engaging a ring in the handle
member with a hook
and pulling the hook upwardly after the step of removing the installation
tool.
Yet another aspect of the invention provides a tool for use in practising the
methods of
the invention. The tool can be used to install a flap valve member in an
inspection chamber in
a sewer system. The tool comprises an elongated shaft extending from to a
handle to a holder,
a stop on the shaft between the handle and the holder and a weight slidably
mounted to the
shaft. The holder comprises: first and second generally parallel opposed
fingers spaced apart
by a distance sufficient to receive a handle member projecting from the flap
valve member; bias
means for resiliently displacing the first finger toward the second finger for
releasably pinching
a handle member projecting from the flap valve member between the first and
second fingers;
and a tab projecting from the holder generally perpendicularly to the shaft at
a base of the
fingers between the handle and the stop.
Yet another aspect of the invention provides a sealing lid for an access pipe
of an
inspection chamber in a sewer system. The sealing lid comprises a circular
plastic body, a piece
of a ferromagnetic material moulded into the plastic body, a sealing member
extending
peripherally around the plastic body, and a pair of opposed locking members
each comprising
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a lug member pivotally mounted to the plastic body and a stop member
projecting adjacent the
lug member. The stop members allow rotation of the lug members between engaged
and
disengaged positions.
BRIEF DESCRIPTION OF THE DRAWINGS
In drawings which illustrate preferred but non-limiting embodiments of the
invention:
Figure 1 is a schematic elevational view of an inspection chamber installed in
a sewage
system according to the invention;
Figure 2A is a longitudinal section through the inspection chamber of the
sewage system
of Figure 1;
Figure 2B is a detailed view of a portion thereof;
Figure 2C is a transverse section through the inspection chamber of the sewage
system
of Figure 1 looking toward the inlet port thereof;
Figures 3A through 3G are views illustrating a sequence of steps for
installing a valve
member according to the invention in the inspection chamber of the sewer
system of Figure 1
with the tool of Figures 4A through 4D;
Figure 4A is an elevational view of a tool for use in the methods of the
invention;
Figures 4B, 4C and 4D are respectively side elevational and top plan views of
a head for
installing a valve member in inspection chambers according to the invention
for use with the
tool of Figure 4A and a side elevational view of a lateral hook for use in the
invention with the
tool of Figure 4A; and
Figures 5A, 5B and 5C are respectively a top plan view, a cross sectional view
and a
bottom plan view of a sealing lid for the access pipe of the sewer system of
Figure 1.
DETAILED DESCRIPTION
Figure 1 shows a sewage system 10 according to the invention. Sewage system 10
carries wastewater from a building 12 to a sewer main 15 through a sewage pipe
16. Sewage
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pipe 16 lies in ground 17 and is inclined slightly toward sewer main 15. An
inspection chamber
20 is located in sewage pipe 16. A first portion 16A of sewage pipe 16 extends
from building
12 to an inlet port 22 of inspection chamber 20. A second portion 16B of
sewage pipe 16
extends from an outlet port 24 of inspection chamber 20 to sewer main 15. An
access pipe 18
extends generally vertically from an access port 26 of inspection chamber 20
to the surface of
ground 17. The upper end of access pipe 18 is closed by a sealing cap 19.
A back-flow prevention valve 30 is located in inspection chamber 20 adjacent
inlet port
22. In use, sewage flows from building 12 through portion 16A of sewage pipe
16, through
inspection chamber 20 and to sewer main 15 through portion 16B of sewage pipe
16. Valve
30 prevents vermin from entering building 12 from sewer main 15 and also
prevents sewage
from backing up from sewer main 15 and flowing into building 12 through
portion 16A of
sewage pipe 16. Valve 30 comprises a valve member 32 pivotally attached inside
inspection
chamber 20.
A distinguishing feature of the invention is that valve member 32 and
inspection
chamber 20 are constructed so that valve member 32 can be inserted into
inspection chamber
after inspection chamber 20 is in place under ground 17. This permits the use
of inspection
chamber 20 to receive a plug 21 (Figure 3) plugging inlet port 22 from inside
inspection
20 chamber 20 while building 12 is under construction (as is required by some
municipalities).
As described below, the methods of the invention also permit valve member 32
to be removed
and replaced through access pipe 18. As such, the invention provides
significant advantages
over the current state of the art which combines a conventional unvalved
inspection chamber
with a separate buried back-flow prevention valve.
The construction of inspection chamber 20 is shown in detail in Figure 2.
Inspection
chamber 20 comprises a housing 40 formed from any suitable material such as
injection-
moulded ABS (Acrylonitrile Butadiene Styrene) plastic. Housing 40 supports
suitable seals
around ports 22, 24, and 26 for sealing connections to portions 16A and 16B of
sewage pipe
16 and access pipe 18. Any suitable seals known to those skilled in the art
may be used. Those
skilled in the art will realize that the shapes and dimensions of ports 22,
24, and 26 may need
to be adapted for the particular type of seals used.
A valve seating surface 42 is provided inside housing 40 around inlet port 22.
Valve
seating surface 42 is preferably planar. Valve member 32 comprises a
transversely mounted
pin 34 attached to a flap member 36 by a short bridge member 37. Pin 34 is
retained by a clip
44. Clip 44 permits pin 34 to pivot relative to housing 40 as indicated by
arrow 46. Normally
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gravity holds valve member 32 with flap member 36 in contact with valve
seating surface 42
so that valve 30 is closed. Wastewater or other sewage arriving at valve 30
pushes flap member
36 in the direction of arrow 46, thereby opening valve 30. A suitable
resilient sealing material
38 is provided either on seating surface 42 or on flap member 36. Preferably
the sealing
material 38 is on flap member 36.
Clip 44 preferably comprises a pair of upwardly projecting resilient fingers
48 which
grip either end of pin 34 with bridge member 37 extending between fingers 48.
Pin 34 is held
in a recess 47 between fingers 48 and adjacent portions of the wall of housing
40. Fingers 48
are preferably moulded integrally with housing 40. Fingers 48 are oriented
upwardly so that
clip 44 detachably receives pin 34 when it is inserted from the direction of
access port 26. A
notch 49 is preferably provided between fingers 48 below recess 47. Notch 49
can be used to
remove a broken valve member 32 as described below.
A handle member 50 projects from a generally central portion of the downstream
surface
of the flap member 36; that is, the handle projects into the inspection
chamber so that it may
be gripped by a tool inserted into the housing 40 via the access pipe 18.
Handle member 50 is
used in the installation of valve member 32 in housing 40 as described below.
In the currently
preferred embodiment of the invention, handle member 50 comprises a ring 52 of
approximately 1 inch in diameter projecting in a plane which bisects valve
member 32. Ring
52 has a central aperture 54.
The method for installing valve member 32 in inspection chamber 20 begins with
inspection chamber 20 buried in soil 17. Plug 21 plugs inlet port 22 from
inside inspection
chamber 20 as shown in Figures 3A and 3B. Plug 21 is then removed by hooking
the ring
handle of plug 21 with a hook 63 lowered through access pipe 18, pulling
upwardly until plug
21 is released, and removing plug 21 through access pipe 18 as shown in Figure
3C. Preferably
hook 63 comprises a spring-loaded catch so that plug 21 cannot fall off from
hook 63 after hook
63 has been fully engaged with the handle of plug 21.
Plug 21 may be removed with a tool 60 as shown in Figure 4A. Tool 60 comprises
a
hook 63 connected to a handle 68 by a shaft 64 which is long enough to reach
down access pipe
18 into inspection chamber 20. Shaft 64 may comprise several sections 66 so
that the length
of shaft 64 can be adjusted for the depth of inspection chamber 20.
As shown in Figure 4A, tool 60 preferably has a weight 72 slidably mounted at
the upper
end of shaft 64 between handle 68 and a stop 70. Weight 72 preferably weighs
about 1
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kilogram. An upward pull on plug 21 may be achieved by sliding weight 72
upwardly against
handle 48 to jolt hook 63 upwardly. In this case, handle 68 acts as a stop. A
separate upper
stop may be provided below handle 68 and above stop 70.
After plug 21 has been removed, hook 63 on tool 60 is replaced with a head 62.
Preferably hook 63 and head 62 are each connected to the end of shaft 64 with
a connector 65
so that they may be readily interchanged. Connector 65 may be a simple
threaded fitting, as
shown, which screws onto the end of shaft 64 or may be another suitable type
of coupling.
A valve member 32 is then attached to the head 62 of too160. As shown in
Figures 4B
and 4C, head 62 comprises a holder 74 for holding a valve member 32 by its
handle member
50. In the currently preferred embodiment of the invention holder 74 comprises
a pair of
fingers 75,76. A bolt 77 extends from first finger 75 through a hole in second
finger 76. A
compression spring 78 on bolt 77 resiliently compresses fingers 75 and 76
together.
Valve member 32 is attached to head 62 by sliding handle member 50 between
fingers
75 and 76 so that it is securely but releasably pinched between fingers 75,76
as shown in
Figures 3D and 3E. When valve member 32 is attached to head 62 a tab 80
projecting from
head 62 lies just above and adjacent pin 34. Holder 74 does not need to grasp
handle member
50 extremely tightly. It is only necessary to hold handle member 50 tightly
enough to reliably
lower valve member 32 through access pipe 18 and align it in inspection
chamber 20 as
described below.
Next, head 62 of tool 60 is lowered through access pipe 18 into inspection
chamber 20
and aligned so that the ends of pin 34 extend between fingers 48 above recess
47 with bridge
member 37 between fingers 48 as shown in Figures 3F and 3G. This is possible
because, as
noted above, fingers 48 are oriented so that pin 34 can be inserted into
recess 47 from the
direction of access port 26.
Pin 34 is then inserted into recess 47 by lifting weight 72 and dropping it
onto stop 70.
This causes portion 80 of head 62 to snap pin 34 downwardly into engagement in
clip 44. If
it is necessary, the step of lifting and dropping weight 72 to snap pin 34
into place can be
repeated. At this point valve member 32 is installed in inspection chamber 20.
All that remains
is to disengage head 62 of too170 from handle member 50. This can easily be
done by simply
lifting handle 68 to draw fingers 75 and 76 off from handle member 50.
The methods of the invention can also be used to remove a valve member 32 from
an
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inspection chamber 20. This might be required, for example, if it becomes
necessary to clean
sewer pipe 16. If valve member 32 is intact then valve member 32 can be
removed simply by
hooking aperture 54 of handle member 50 with a suitable hook and pulling
sharply upwardly.
Tool 60 is preferably constructed so that head 62 can be removed and replaced
with a hook 63
for this purpose. Hook 63 can also be used to remove plugs 21 as described
above. When tool
60 is used this way then weight 72 can be hammered upwardly against handle 68
to provide
sharp upward force on hook 63 to dislodge a valve member 32 or a plug 21.
If valve member 32 has broken off, then it is still usually possible to
replace valve
member 32 without digging down to inspection chamber 20. Typically valve
member 32 will
break at bridge member 37 because bridge member 37 is generally the weakest
part of valve
member 32. If this happens then a small laterally extending hook 100 can be
attached at the
end of tool 60 in place of hook 63 or head 62 and inserted into notch 49. The
laterally
extending hook 100 can then be lifted upwardly to remove pin 34 from clip 44.
The portion
of a broken off valve member 32 attached to pin 34 is generally small enough
that it can safely
be left to wash into sewer main 15. The rest of valve member 32 including flap
member 36 can
be fished out from inspection chamber 20 by hooking handle member 50. The
laterally
extending book 100 may be provided in a kit with a hook 63, a head 72 and
other components
of tool 60.
Sealing lid 19 is preferably made of a suitable plastic material. Sealing lid
19 preferably
comprises a piece 90 of a ferromagnetic metal, such as iron or steel so that a
metal detector can
be used to rapidly locate sealing lid 19 and access pipe 18. Most preferably,
sealing lid 19 is
moulded from a suitable plastic material and piece 90 is moulded into sealing
lid 19. For
example, if sealing lid 19 is injection moulded then piece 90 can be placed
into the mould
before plastic is injected After the plastic has been injected then piece 90
is partially or entirely
encased in plastic.
Sealing lid 19 preferably comprises one or more locking members 92 for locking
sealing
lid 19 in place at the top of access pipe 18. Locking members 92 may comprise,
for example,
lugs 94 which can be turned to project outwardly and engage an inwardly
projecting step 95 at
the upper end of access pipe 18 using cap screws 96. Preferably, a post 98 is
provided adjacent
each of lugs 94. Posts 98 provide positive stops at the extended (as shown in
solid lines in
Figure 5C) and retracted (as shown in dotted outline in Figure 5C) positions
of lugs 94.
While the currently preferred embodiment of the invention is described above,
it will
be clear to those skilled in the art that there are many ways to vary the
designs of the various
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components described above without departing from the broad scope of the
invention. For
example, clip 44 could be any suitable kind of clip capable of receiving and
detachably and
pivotally retaining a valve member comprising a flap member 36 and oriented to
receive the
valve member from the direction of access port 26. While it is preferred,
handle member 50
need not comprise a ring, as described. It is only necessary that handle
member 50 provide a
means for holding a valve member 32 to a tool 60 so that valve member 32 can
be positioned
in inspection chamber 20 and engaged with clip 44. It is preferable, however,
that handle
member 50 comprise a ring because a ring can be grabbed with a hook to remove
a valve
member 32. Tool 60 need not be equipped with a sliding weight 72. Although it
is not
preferred, a separate hammer could be used to hammer on an end portion of tool
60 instead.
As will be apparent to those skilled in the art in the light of the foregoing
disclosure,
many further alterations and modifications are possible in the practice of
this invention without
departing from the spirit or scope thereof. Accordingly, the scope of the
invention is to be
construed in accordance with the substance defined by the following claims.
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