ACCESS CHAMBER

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Australian Patent Application No. 2023241288, filed Oct. 4, 2023. The entire disclosure of the above application is incorporated herein by reference.

FIELD

The present invention relates to a chamber base and an access chamber including the chamber base. It also extends to a set of components for forming an access chamber and a method of forming an access chamber. Further, it extends to a pipeline installation including the access chamber.

This invention relates particularly, but not exclusively to, an access chamber for a below ground pipeline installation that is used in a waste water system, and a method of forming an access chamber received in the ground. It will therefore be convenient to hereinafter describe the invention with reference to this example application. However, it is to be clearly understood that the invention is capable of broader application.

BACKGROUND

Underground pipe systems for stormwater and sewage include maintenance or access chambers at pipe junctions to allow for inspection and/or maintenance. Generally, an access chamber allows a worker entry from the surface through an opening. Maintenance chambers allow a camera, rod or other pipe clearing device to enter and inspect underground pipes.

An access chamber includes a cylindrical base with an outlet and one or more inlets and a flow path connecting the inlet(s) and outlet. A riser extends from the base to the ground surface. Typically, the water pipes are located up to about 6 m below the ground surface and consequently, the plastic pipes are rated for a maximum depth of 6 m. The base of the access chamber may have a diameter of 800 to 1200 mm and the riser may have a similar diameter to the base on which it is mounted.

FIG. 1 illustrates an access chamber having a chamber base that is cast in situ in the ground by means of concrete. The concrete access chamber base has their inlet and outlet ports drilled out of the concrete wall. Infill concrete is poured into the base to create a flow path inside the base in a process known in the art as ‘benching’. A concrete riser component is then mounted on top of the base. While such a chamber base for the access chamber is sturdy and secure, it will be appreciated that it is very labor intensive and expensive to install.

Alternatively, basic concrete bases and riser components may be pre-cast with pre-formed holes and benched channels. For example, FIG. 2 illustrates a base for an access chamber that is pre-cast from a concrete material in a factory and transported to the site of the access chamber. On site, the chamber base is lowered into an excavation that receives the chamber base. It will be readily appreciated that it will be expensive to manufacture such a concrete chamber base. It will also be heavy and unwieldy to handle and transport the concrete base to an installation site.

In more recent times, it has been known to fabricate an access chamber and, more specifically, a chamber base from some other materials. Typically, the chamber base and a riser are formed separately, and are assembled once the chamber base is received within the excavation.

In summary, access chambers are currently often manufactured on site, and this is an unwieldy and time-consuming process.

Any reference to background art in the background above is not intended to, and should not be taken as, an acknowledgment, statement, suggestion, or admission that the referenced prior art forms part of the common general knowledge in Australia or in any other country.

SUMMARY OF THE INVENTION

In concordance with the instant disclosure, a chamber base for an access chamber used in a below ground pipe installation, has surprisingly been discovered.

Applicant believes there is a need for large numbers of access chambers for use in underground piping systems. Further, Applicant recognizes that current techniques for providing below ground access chambers are less than optimal. Accordingly, it would be beneficial if these access chambers could be provided more efficiently and more cost effectively.

According to one aspect of the invention there is provided a chamber base for an access chamber used in a below ground pipe installation, the chamber base comprising: a base body comprising a bottom wall and a side wall extending up from the bottom wall, and a plurality of ports formed in the side wall, wherein the base body is molded of a polymeric material; and a flow path insert formed separately from the base body received within the base body, the flow path insert defining a flow path from one port across the flow path insert to at least one other port on the side wall.

At least one port of the plurality of ports may be integrally molded with the base body. The base body may be molded by injection molding.

The plurality of ports may comprise four ports that are spaced substantially equiangularly apart from each other around the circumference of the side wall. Further, the four ports may be integrally formed with the base body by the molding operation forming the base body.

The base body may further comprise a base support received within the base body for strengthening the base body to resist deformation thereof when exposed to external pressure.

The base support may be formed integrally with the base body when the base body is molded.

The base support resists inward deformation of the side wall of the base body, e.g. towards a lower region thereof, due to ground water in the ground in which the access base is received. At a depth of 6-8 under the ground, a column of ground water exerts significant pressure on adjacent wall of a structure or body.

The base support may comprise a series of reinforcing formations on the bottom wall of the base body. The series of reinforcing formations may define a plurality of voids therebetween. The series of reinforcing formations may extend across the cross-sectional area of the base body.

In one form, the base support may resemble a honeycomb formation (with the term ‘honeycomb formation’ being construed broadly).

The base body may further comprise at least one locating formation, and the side wall of the flow path insert may comprise at least one complementary locating formation engaging said at least one locating formation.

Said at least one locating formation and complementary locating formation are positioned to locate the flow path insert in its correct rotational position on the base body.

In the correct rotational position, the flow path on the flow path insert will align with the associated fluid flow ports on the side wall of the base body.

The at least one locating formation may comprise a tab on the side wall or bottom wall of the base body, e.g. projecting up from the bottom wall, and the complementary locating formation may comprise a recess in the insert side wall that receives the tab.

In one form, the chamber base may comprise a plurality of locating formations that are spaced from each other around the perimeter of the bottom wall or side wall.

The flow path insert may be integrally molded as a single piece from polymeric material.

The insert side wall may be configured to be received within the side wall with a working clearance.

During assembly, the flow path insert may be lowered into the base body from above when the access chamber is constructed.

The flow path insert may be mounted on and fixed to the chamber base prior to installation of the chamber base in an excavation in the ground. For example, the flow path insert may be fixed to the chamber base in a factory prior to transport to the site where it will be installed.

The flow path insert may be permanently fixed to the chamber base by welding the flow path insert to the chamber base around the periphery of the insert side wall.

An upper edge of the insert side wall may be welded to the chamber base around the circumference of the chamber base.

At least one port may comprise a short cylindrical section, with open ends that form a port opening in the side wall of the base body, for coupling to a pipe fitting.

The at least one port may further comprise a swivel arm operatively coupled to each said port that is able to swivel relative to the side wall.

Each swivel arm may comprise a swivel seat that does not move relative to the side wall of the chamber base on which it is mounted, and a complementary swivel member movably mounted on the swivel seat.

The swivel arm may further include a lock nut having an internal screw formation mounted over the swivel member for mounting the swivel member on the swivel seat. The swivel seat may include a screw formation on its outer surface for engaging the internal screw formation to hold the swivel member in position on the swivel seat.

Each swivel arm may further include a pipe coupling formation remote from the port for coupling the swivel arm to an external pipe, e.g. an external water pipe.

The base body may further comprise a plurality of key formations on an outer surface of the side wall of the base body for keying the base body to a surrounding backfill.

At least two of the key formations may extend fully circumferentially around the side wall of the base body. At least one further key formation may extend at least part of the way around the circumference of the side wall, e.g. it extends part of the way, but not fully around, the circumference of the side wall.

The base body may be substantially circular cylindrical and define an internal space having a circular cross section. Conveniently, the base body may have a diameter of 400 to 1200 mm diameter, and in some forms, the diameter may be 400 to 600 mm, and in other forms, the diameter may be from 800 to 1200 mm. A larger size of base body with a diameter of 1000 to 1200 mm meets current standards for access chambers and is sufficiently large to receive a worker therein.

The bottom wall and side wall of the base body may be integrally formed by injection molding, from any suitable plastic material, e.g. PVC, PP, or PE.

The flow path insert may be similarly injection molded from any suitable plastic material, e.g. PVC, PP, or PE by injection molding.

The chamber base may include any one or more features, or combinations of features, of the chamber base defined in any other aspects of the invention.

According to another aspect of the invention there is provided a kit (or set of components) for forming an access chamber in a below ground pipeline installation, the set of components comprising:

- a standard base body comprising a bottom wall and a side wall and having at least one port formed in the side wall; and
- a plurality of flow path inserts formed separately from the base body for being received within the base body with a close fit, wherein each flow path insert defines a different flow path for conveying liquid from at least one inlet port to an outlet port in use.

The standard base body may be integrally molded of a polymeric material as a single integral body with the at least one port formed therein, e.g. by injection molding.

Each flow path insert may comprise an insert side wall and an insert top wall extending across an end of the side wall.

The insert side wall may be received within the side wall of the base body in use.

Each of the plurality of flow path inserts may be integrally formed as a single component, and sized to be individually received, within the base body with a close fit (i.e. only 1 flow path insert can be received within the base body at a time).

Each flow path insert may define a flow path from one port on the side wall to at least one other port on the side wall when mounted on the base body in use, and each of the flow path inserts defines a different flow path.

In one example form, the base body may comprise four ports formed on the side wall thereof, and the ports may be spaced equiangularly around the circumference of the side wall.

The top wall may form an operatively upper surface of the flow path insert and the top wall may close off the bottom wall of the base body when mounted on the base body in use.

Each flow path insert may be integrally formed as a single component, e.g. by a molding operation. In one example form the molding operation may be injection molding.

One of said plurality of flow path inserts may be configured to form a flow path that connects to four ports on the base body in use.

Another of said plurality of flow path inserts may be configured to form a flow path that connects to three ports on the base body in use.

Yet another of said plurality of flow path inserts may be configured to form a flow path that connects to two ports on the base body in use.

In one variation, where the flow path insert is configured to connect to two ports, the flow path may extend linearly through the flow path insert for connecting two diametrically opposed ports.

Instead, in another variation, where the flow path insert is configured to connect to two ports, the flow path may turn through 90 degrees for connecting two adjacent ports that are orthogonal to each other.

The kit may further comprise a riser for mounting on an upper end of the side wall in use.

The kit may further comprise a top member for mounting on the riser, or for mounting on an upper end of the base body in use. The top member may have a closable opening formed therein for providing access to an interior of the access chamber.

According to another aspect of the invention there is provided an access chamber comprising:

- a chamber base as defined in any one of the preceding aspects of the invention; and
- a top member, mounted directly or indirectly, on the chamber base.

The access chamber may further comprise a riser mounted on the chamber base between the chamber base and the top member.

The chamber base and the top member may each have a substantially complementary cylindrical cross-sectional configuration, and the chamber base and the top member may be axially aligned with each other.

Further, the chamber base and the riser may each have a substantially complementary cylindrical cross-sectional configuration, and the chamber base and the riser may be axially aligned with each other.

The riser may be formed of a polymeric material, e.g. PVC, PP, or PE, and the riser may be sealed to the base body around the circumference of the side wall of the base body.

The top member may be formed of a polymeric material, e.g. PVC, PP, or PE, and the top member may be sealed to the chamber base or the riser around the circumference of the side wall of the base body.

The top member may be sealed to the riser or base body around the circumference of the riser or base body, e.g. by means of a circumferential seal extending around the top member.

The top member may comprise a side wall and a top wall mounted on the side wall, and the top wall may further include a closable opening or hatch formed therein.

The chamber base may include any one or more of the features, or combination of features, of the chamber base defined in any other aspect of the invention.

According to another aspect of the invention there is provided a method of forming an access chamber that is received in the ground, the method comprising:

- lowering a chamber base in accordance with any one of the other aspects of the invention, into an excavation in the ground.

The method may further comprise mounting a riser on the chamber base.

The method may further include mounting a top member with a closable opening formed therein, on the riser.

Instead, the method may comprise mounting a top member with a closable opening formed therein, directly on the chamber base.

The method may further comprise operatively coupling each external pipe to a port on the base body, and then back filling the excavation.

The base body may include any one or more of the features, or combination of features, of the chamber base defined in any preceding aspect of the invention.

Similarly, each flow path insert may include any one or more of the features, or combination of features, of the flow path insert defined in any preceding aspect of the invention.

According to yet another aspect of the invention there is provided a below ground pipeline installation comprising:

- an access chamber as defined in any one of the other aspects of the invention; and at least two pipes, each pipe being operatively coupled to a different port on the base body.

The access chamber, including the chamber base, and the flow path insert of the access chamber may include any one or more of the features, or combination of features, of the chamber base, the base body and the flow path insert defined in any preceding aspect of the invention.

Further, the riser and the top member may include any one or more of the features, or combination of features, of the riser and top member, defined in any preceding aspect of the invention. The pipeline installation may include three pipes operatively coupled to three different ports on the base body. Instead, the pipeline installation may include four pipes operatively coupled to four different ports on the base body. Yet further, instead, the pipeline installation may include two pipes operatively coupled to two different ports.

The pipes may be located at a depth of 1 to 6 m below the surface of the ground, e.g. 5 to 6 m below the ground.

According to yet another aspect of the invention there is provided a chamber base for an access chamber used in a below ground pipe installation, the chamber base comprising: a base body having a bottom wall and a side wall extending up from the bottom wall; at least one port formed on the side wall; and a flow path formation received within the base body that defines a flow path extending to said at least one port.

The flow path formation may be formed separately from the base body.

The flow path formation may comprise a flow path insert that is inserted into base body.

The flow path insert may be configured such that it is received within the side wall with a working clearance. The flow path insert may be lowered into the base body from above when the access chamber is constructed.

The flow path insert may be permanently fixed to the chamber base, e.g. by welding the flow path insert to the chamber base around the periphery of the insert, e.g. by welding an upper edge of the side wall of the insert to the side wall of the base body.

The flow path insert may define a flow path that fluidly connects two or more ports on the base body.

The flow path insert may define a flow path that fluidly connects three ports or four ports on the base body.

Further, the flow path insert may define a flow path that fluidly connects two ports on the base body. In one form, the two ports may be axially aligned with each other on the base body. In another form, the two ports may extend orthogonally to each other on the base body.

The chamber base including the base body and the flow path insert may include any one or more of the features, or combination of features, of the chamber base, the base body, and the flow path insert defined in any other aspect of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A chamber base, an access chamber and a related pipeline installation for a liquid, such as water or waste water, in accordance with the invention may be produced in a variety of forms. It will be convenient to hereinafter describe in detail some embodiments of the invention with reference to the accompanying drawings. The purpose of providing this detailed description is to instruct persons having an interest in the subject matter of the invention how to carry the invention into practical effect. However, it is to be clearly understood that the specific nature of this detailed description does not supersede the generality of the preceding summary section. The Detailed Description refers to the accompanying drawings, in which:

FIG. 1 is a schematic drawing of a base of a prior art concrete access chamber that is cast in situ in an excavation in the ground;

FIG. 2 is a schematic drawing of a base of a pre-cast concrete access chamber that is transported to a site and then lowered into an excavation that is once again known in the prior art;

FIG. 3 is an exploded perspective view of a chamber base for an access chamber in accordance with one embodiment of the invention;

FIG. 4 is an exploded perspective view of a chamber base for an access chamber that is a variation on the chamber base in FIG. 3;

FIG. 5 is an exploded perspective view of an access chamber in accordance with one embodiment of the invention having the chamber base of FIG. 3;

FIG. 6 is a cross sectional view of an access chamber including the chamber base of FIG. 3 or 4 in accordance with another embodiment of the invention;

FIG. 7 is an expanded perspective view of a top member for use on the chamber base of FIGS. 3 and 4;

FIG. 8 is an expanded perspective view of a top member (different to that in FIG. 7) for use on the chamber base of FIGS. 3 and 4;

FIG. 9 is a schematic plan view of a pipeline installation including the chamber base of FIG. 3;

FIG. 10 is a schematic drawing showing how a flow path insert received in the base body of the chamber base shuts off the ports that are not being used when inserted therein;

FIG. 11 is an exploded upper perspective view of a chamber base for an access chamber in accordance with another embodiment of the invention;

FIG. 12 is a cross-sectional view of the chamber base in FIG. 11 together with a thumb nail sketch of a part of the chamber base;

FIG. 13 is an exploded upper perspective view of a chamber base for an access chamber sized to receive a person therein;

FIG. 14 is a cross-sectional view of the chamber base in FIG. 13;

FIG. 15 comprises upper and lower perspective views of a flow path insert for the chamber base of FIG. 13 forming a flow channel; and

FIG. 16 is an upper perspective view of a riser for use with the access chamber in FIG. 13.

DETAILED DESCRIPTION

FIGS. 1 and 2 illustrate two access chambers known in the prior art. These access chambers have been described above in the background section and as they do not form part of the invention they will not be described further in this detailed description.

FIG. 3 illustrates a chamber base in accordance with one embodiment of the invention that is indicated generally by the reference numeral 10. The chamber base is for use in forming an access chamber received in the ground and forming part of a pipeline installation.

The chamber base 10 is formed by a base or chamber body 12 comprising a bottom wall 16, and a side wall 14 extending up from the bottom wall 16 around its periphery. The chamber base 10 has a plurality of fluid flow ports 18 formed on the side wall 14. In the illustrated embodiment, the chamber base 10 is circular cylindrical and has four ports 18 spaced equiangularly around the circumference of the side wall 14. The side wall 14 has a plurality of ribs 19 formed on an external surface thereof. The ribs 19 extend concentrically around the body 16 transverse to a longitudinal axis of the access base 10, at spaced intervals along the axial length of the base body 12. The ribs 19 help to key the base body 12 to the surrounding ground within which it is received.

The chamber base 10 further includes a flow path formation in the form of a flow path insert 20 that is received within the chamber base 10 and defines at least one flow path therein. The flow path formation or flow path insert 20 defines a flow path, from one port on the side wall 14, through the flow path insert 20, to at least one other port on the side wall 14, spaced from the first port. Often one of the ports forms an outlet port and the other ports form inlet ports. Typically the number of inlet ports varies from 1 to 5.

Each of the components will now be described in further detail below.

The chamber base 10 further comprises an arm, e.g. a stub arm 30 on each port 18 projecting outward away from the side wall 14. Each stub arm 30 has a flow path defined therein leading to an opening (liquid opening forming an inlet or outlet) formed in a free end thereof remote from the side wall 14.

Further, each stub arm 30 is movably mounted on the base body 12. For example, in the illustrated embodiment, the stub arm 30 comprises a swivel coupling that couples the arm 30 to the base body 12. This feature enables each stub arm 30 to swivel to some extent on the base body 12 and this permits some movement of the base body 12 relative to the pipes 102, 104 to which it is connected. This feature accommodates movement in the ground and reduces the forces being transmitted through to the attached pipes.

The flow path insert 20 comprises a side wall 21 and a top wall 23. It does not have a bottom and opens downwardly in a direction away from the top wall 23. The flow path insert 20 has a diameter that is sized and configured to be received within the base body 12 with a working clearance. This enables the flow path insert 20 to be slidingly received within the base body 12 during construction or assembly of the access chamber 10. As indicated in the drawings, the base body 12 is circular cylindrical and has a height that is broadly comparable to its diameter. It follows that the flow path insert 20 also has an overall circular cylindrical configuration.

The flow path insert 20 has a flow channel or flow path 25 formed therein that communicates with at least two flow ports 18. The flow path insert 20 shown in FIG. 3 has a flow path or flow channel 25 that is configured to communicate with all four flow ports 20 and comprises four branches forming a cross.

The base body 12 and flow path insert 20 have locating formations formed thereon for locating the flow path insert 20 in the correct rotational position on the base body 12. In the illustrated embodiment, the locating formations comprise locating tabs (not shown) on the side wall 14 or bottom wall 16 of the base body 12 that interact with complementary recesses 29 on the side wall 21 of the flow path insert 20. This feature helps workers to place the flow path insert 20 in the correct rotational position on the base body 12 during installation. The flow path insert 20 is lowered into the base body 12 and then rotated until the complementary locating formations 29 on respectively the base body 12 and flow path insert 20 engage.

Each arm 30 further comprises a swivel arrangement which will now be described in more detail. Each swivel arrangement comprises a swivel seat 32 that is fast with the side wall 14 of the base body 12 and a movable swivel member 34 that is movably mounted on the swivel seat 32. Each swivel arrangement further includes a lock nut 36 that secures the swivel member 34 to the swivel seat 32. It also includes an O-ring seal 38 sealing the member 34 to the seat 32 to resist leakage of liquid.

In the illustrated embodiment, there are two forms of coupling on the swivel member 34. The first option 34A is a female socket formation for coupling to a male spigot on an external pipe. The other option 34B is a male spigot for coupling to a female socket on an external pipe. Both the male spigot and female socket are standard pipe fittings that are used in pipeline installations.

FIG. 4 illustrates a chamber base 10 in accordance with another embodiment of the invention.

In FIG. 4, the flow path insert 20 is configured with a flow path 25 that communicates with only three of the four ports 18 on the base body 12. By contrast in the embodiment shown in FIG. 3 above, the flow path insert 20 is configured to be in fluid communication with all four ports 18 on the base body 12.

Correspondingly in FIG. 4, the chamber base 10 has three arms 30 on the three active ports of the base body 12. The fourth port does not have an attached arm and is closed off (or blanked off) by the side wall 21 of the flow path insert 20 which extends across and blocks off the port 18 when it is fitted to the base body 12. The side wall 21 provides a convenient and effective way of sealing off the port 18 when it is not being used in an application. Further, a cap (not shown) can also be mounted over an outside of the blanked off port 18.

It will be appreciated that yet other configurations of flow path inserts having different flow channels could also be devised. In FIG. 4, two other examples of a flow path insert 20 communicating with only two ports 18 on the chamber base 10 are shown. In this case, the two active ports 18 are operatively connected to the swivel arms 30 which in turn are operatively coupled to water pipes 102,104. The other two ports 18 (that are not being used) are blanked off by the side wall 21 of the flow path insert 20 which is configured to close off and scaling the ports 18.

FIG. 10 of the drawings schematically illustrates how the flow path insert 20 is configured to close off the ports 18 that are not being used with a specific flow path configuration. The side wall 21 of the flow path insert 20, which is positioned up against the side wall 14 of the base body 10 extends across and closes off the port 18. Further, a perimeter of the port 18 (that has been blanked off) may be sealed to the side wall 21 of the flow path insert 20 around its circumference by any suitable technique, for example a type of welding.

FIG. 5 is an exploded perspective drawing of an access chamber in accordance with an embodiment of the invention. In FIG. 5, the access chamber is indicated generally by the reference numeral 50.

The access chamber 50 comprises the chamber base 10 mounted in an operatively lowermost position and a riser 52 mounted on an upper end of the chamber base 10. The access chamber 50 is received within the ground and is operatively connected to a plurality of pipes (not shown). The riser 52 is circular cylindrical (like the chamber base 10) and has a complementary shape to the chamber base 10 with a similar cross-sectional area. The riser 52 is mounted to and sealed to the chamber base 10 around its circumference. Conveniently, the riser 52 is sealed to the chamber base 10 by means of a rubber sealing O-ring 54 sandwiched between the side wall 14 and the riser 52 extending around the circumference of an upper end of the side wall 14 of the chamber base 10.

The riser 52 extends from the chamber base 10 up the height or volume of the access chamber 50 providing an internal space within which a maintenance worker can work. The top of the riser 52 is closed off, e.g. adjacent to the surface of the ground, and this may be achieved by using a top member like that shown in FIGS. 7 and 8 and described below.

FIG. 7 illustrates a chamber fitting or top member for mounting directly or indirectly on the chamber base 10. In the drawings, the top member indicated generally by reference numeral 80 comprises a side wall 84 for engaging with the structure of the access chamber beneath it, and a top wall 86, extending over the top of the side wall. Further, the top wall 86 has a closable upper opening or access hatch 88 formed therein through which a person on the ground surface can get access into the access chamber 50.

FIG. 8 illustrates a chamber fitting or top member for mounting on the chamber base 10 which is a variation on that shown in FIG. 7. In the drawing, the top member is indicated generally by reference numeral 90. In FIG. 8, the top member 90 has an operatively upper access hatch or closable opening 98 on a top wall 90 that is smaller than the hatch 82 in FIG. 7. Other than that, the structure and function of the fitting 90 is very similar to that of the fitting 80 in FIG. 7.

FIG. 6 illustrates an access chamber 50 having a top member 80 fitting like that shown in FIG. 7 mounted directly on the chamber base 10 in FIG. 3 (and does not have a riser).

As shown in the drawings, the side wall 84 of the top member 80 is received within an upwardly opening coupling formation 85 on the chamber base 10. The top member 80 has a circumferential sealing formation 87 on the outer surface of the wall 84 that seals up against the base body 10. Further, the access hatch 88 provides access into the interior of the access chamber 10.

FIG. 9 is a schematic plan view of a pipeline installation having an access chamber like that in FIG. 5.

The pipeline installation which is indicated generally by reference numeral 100 comprises a set of four waste water pipes converging on the access chamber 50. Typically, in an embodiment like this, three inlet pipes 102 feed waste water into the access chamber 50 and one outlet pipe 104 carries waste water away from the access chamber 50. Thus, in this FIG. 9 embodiment, each of the ports 18 is operatively connected to a pipe and there are no ports 18 that are blanked off and inactive.

During construction, the access base 10 is lowered into an excavation in the ground. The base body 12 is keyed into the surrounding ground material by the ribs 19 on its outer surface. When the excavation is back filled with the access base 10 in the ground, the loose earth fills in the gaps between the ribs 19 and helps to hold the access base 10 in its fixed vertical position below the ground surface. Water in the ground can apply a lifting force to the access chamber tending to lift it out of the ground and this lifting force needs to be resisted.

A flow path insert 20 is selected having a flow passage that matches the arrangement of pipes that are to be coupled to the access chamber 50. For example, if four pipes are connected to the access chamber 50 a flow path insert 20 having flow channel sections like that shown in FIG. 3 will be used. The flow path insert 20 which can be received in the base body 12 with a working clearance is then lowered into the base body 12.

The flow path insert 20 is then fixed or joined to the base body 12. This is done by welding the insert 20 to the side wall 14 around the periphery of an upper edge of the flow path insert 20. The welding stops the flow path insert 20 from lifting, and floating off, when the access chamber 50 is filled with liquid and is therefore important. It also seals the base body 12 to the flow path insert 20 around the circumference of the top wall 23 of the flow path insert 20 to resist the ingress of water into the space or void formed between the flow path insert 20 and the bottom wall 16 of the base body 12 (shown best in FIG. 10). External liquid flow pipes 102, 104 are then operatively connected to the four arms 30 on the chamber base 10. This is accomplished using the spigot or socket couplings 34A and 34B shown in the drawings which are standard couplings in the plumbing art.

In use, the access chamber 50 can accommodate some settling within the ground material within which it is located without transferring stress to the pipes 102, 104 to which the chamber 50 is connected. Basically, the ability of each arm 30 to swivel accommodates relative movement between the access chamber 50 and the surrounding ground in which the pipes 102, 104 are located. This limits the stress placed on the pipes 102, 104 extending away from the access chamber 50 when there is movement in the ground. Therefore, the access chamber 50 and associated pipes are less prone to breaking or cracking and consequently also less prone to water leaks.

FIGS. 11 and 12 illustrate a chamber base 10 for an access chamber 50 in accordance with another embodiment of the invention. This chamber base 10 has many similarities to the chamber base described above with reference to FIG. 2. Accordingly, the following description will focus on the differences between this embodiment and the earlier embodiment.

The base body 12 of the chamber base 10 in FIG. 11 further comprises a support structure or base support 80 extending up from the bottom wall 16 of the base body 12.

The base support 80 strengthens the base body 12 to resist deformation thereof when exposed to external pressure. The base support 80 resists inward deformation of the side wall 14 of the base body 12, towards a lower region thereof, due to ground water in the ground in which the chamber base 10 is received. At a depth of 6-8 m under the ground, a column of ground water exerts significant pressure on the base body 12 and it needs to be able to withstand this pressure. The base support 80 also holds and supports the flow path insert 20 in position up above the bottom wall 16 of the base body 12 and helps to provide fine tolerance vertical positioning of the flow path insert 20 and alignment of the flow channels in the flow path insert 20 with their associated ports 18.

In the illustrated embodiment, which is merely one example form, the base support 80 comprises a series of reinforcing formations or walls 82 on the bottom wall of the base body 12 with voids in between the series of reinforcing formations 82. In some respects, the base support 80 may resemble a honeycomb formation (with the term ‘honeycomb formation’ being construed broadly).

The base support 80 is molded integrally with the base body 12 in the injection molding operation that is used to form the chamber base 10. FIG. 12 shows how the flow path insert sits or rests on top of the base support 80.

FIGS. 13 and 14 illustrate a chamber base for an access chamber in accordance with another embodiment of the invention. This chamber base 10 has many similarities to the chamber base 10 described above with reference to FIG. 3. Accordingly, the following description will focus on the differences between this embodiment and the earlier embodiment.

The chamber base 10 has a base support 80 like that in FIGS. 11 and 12 that supports a lower region of the base body 12 and helps to resist inward deformation of the side wall 14. The chamber base 10 in FIG. 13 has a diameter of 1200 mm and is sized to be sufficiently large to receive a worker therein. This chamber base 10 is therefore used for the larger style of access chambers 50 which require workers to descend into the actual shaft of the access chamber 50 formed by the riser 52 for inspections and/or maintenance work.

In this embodiment, the flow path insert 20 has a flow path 25 with a cross arrangement where three inlet pipes 102 merge into one outlet pipe 104. Further, the flow paths 25 of two of the incoming streams are curved along their length to preserve the momentum of liquid flowing into the access chamber 50 and conserve energy.

FIG. 15 shows an alternative and different flow path insert configured for use on the chamber base in FIG. 13.

The flow path insert 20 has a tee arrangement in which the flow path 25 comprises two inflow sections (from two inlet pipes) which merge into one section leading to an outflow or discharge pipe.

The drawing also shows an underside 82 of the flow path insert 20. It shows that the underside 82 of the flow path insert 20 is open, and is not filled in or closed off by a bottom wall. The other flow path inserts 20 illustrated in the earlier figures of this patent specification, and in particular FIGS. 3, 4, and 6 have the same basic structure on their underside 82.

FIG. 16 shows a riser 52 that is sized and configured for mounting on the chamber base 10 in FIG. 13. This riser 52 has similar structural features to the riser 52 illustrated in FIG. 5 of the drawings for mounting on the chamber base 10 of FIG. 3.

Plastic has many advantages over concrete including a light weight, case of installation and corrosion resistance. However, different chamber bases have different flow pattern configurations depending on application and therefore (as they are molded as a single integral entity), a different mold is required for different flow channel arrangements inside the base. As there are many different configurations of flow channel arrangements required for different applications, the cost of tooling up to make individual molds for all these different chamber bases with integrally molded flow path formations, is very high.

One working advantage of the access chamber and chamber base described above with reference to the drawings is that a universal base body can be molded in a single standard configuration. This universal base body can then be modified for different flow path configurations using different flow path inserts.

This way a whole range of flow modifiers with different flow paths can be used together with a single universal base body 10. That is, a single manufactured chamber base can be adapted for a range of different applications. This obviates the need to mold a different base body for every different flow path arrangement. Rather, a single large die can be used to make a universal base body. The flow path configuration of the chamber base can be modified by selection of a suitable flow path insert from a selection of flow path inserts having different configurations.

There are significant cost advantages conferred by being able to injection mold a single standard base body for the access chamber which can then be used for multiple applications. The tooling and manufacturing infrastructure required to manufacture a different base for each variation in flow channels is substantial. Further, greater inventory and storage requirements are also imposed on utilities when a different chamber base needs to be manufactured for each different flow channel configuration.

By contrast, if one standard form of base body can be manufactured and stored for a range of different situations and applications (instead of different base bodies being molded for each different application), tooling requirements, working capital requirements, and both inventory and storage requirements can be significantly reduced.

Another working advantage is that the side wall with its spaced ribs confers an additional strength on the chamber base when compared to a chamber base with planar side wall. Further, the ribs on the side walls enable the chamber base to be keyed into the ground when the excavation receiving the base body is backfilled. This secures it in position and resists it from lifting.

The chamber base can be assembled in a factory or workshop prior to being transported to a site. A suitable flow path insert is selected and then inserted into the base body. The insert is then welded to the base body around its circumference to permanently fix the two components to each other. The chamber base is then ready for transport to a site. The final assembly of the access chamber can be carried out on site. Yet another working advantage is that the access chamber can be easily and efficiently installed on site and connected to the water pipes.

Another working advantage of the embodiment described above with reference to the drawings is that the chamber can accommodate movement of the chamber base relative to the pipes to which it is connected. This is because the swivel feature of the stub arms can accommodate these movements.

In this specification, the term ‘access chamber’ shall be given a broad meaning and shall include inspection chambers, manholes and the like. In particular, it shall be understood to cover any type of chamber that allows access to an underground pipe network without limitation.

In this specification, the use of the terms ‘suitable’ and ‘suitably’, and similar terms, is not to be read as implying that a feature or step is essential, although such features or steps referred to as ‘suitable’ may well be preferred.

In this specification, the term ‘comprising’ is intended to denote the inclusion of a stated integer or integers, but not necessarily the exclusion of any other integer, depending on the context in which that term is used. This applies also to variants of that term such as ‘comprise’ or ‘comprises’.

It is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative only and not limiting. All such modifications and variations thereto, as would be apparent to persons skilled in the art, are deemed to fall within the broad scope and ambit of the invention as is set forth herein. Changes in detail or structure may be made without departing from the basic elements of the invention as defined in the following claims.

ACCESS CHAMBER

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