NZ592757A - Plastic access chamber - Google Patents

Abstract

A plastic access chamber comprising an unitary body 11 with a base and at least one wall extending from the base, where the body 11 is configured to receive a removable lid 12 such that a watertight seal is created between the lid 12 and the top of the at least one wall. The body 11 has at least one port 23 in the wall(s), where the port(s) 23 are adapted to receive a watertight fitting. The watertight fitting comprises a nut 25 and a compression fitting 24, with the nut 25 and compression fitting 24 each having an aperture dimensioned to frictionally receive a conduit 21 such that the conduit 21 can enter a port 23 and the combined action of at least the nut 25 and compression fitting 24 creates a watertight seal about the conduit 24.

Description

PATENTS FORM NO. 5 Fee No. 4: $250.00 PATENTS ACT 1953 COMPLETE SPECIFICATION Divisional Application from New Zealand Patent Application No, 591883 WATERTIGHT CHAMBER We, RX Plastics Limited a New Zealand company of 445 - 453 West Street, Ashburton 7700; Chris Clay, 48 Lane Street, Allenton, Ashburton, 7700; and Jonathan Gray, 354 Ashburton Staveley Road, 1 RD, Ashburton 7771 hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement: 1A (followed by 1) Received at IPONZ on 2 June 2011 WATERTIGHT CHAMBER Field of Invention The invention relates to an access chamber. More particularly, the invention relates to a watertight access chamber and method for using same.

Background to the Invention Access chambers are used to provide access to underground pipes and cabling for the purposes of maintenance and installation. Different sizes and strengths of access chamber are required for different purposes. Some of the factors that affect the required properties of an access chamber are: the location of the access point, the depth of the pipes/cabling, the properties of the surrounding soil, the frequency of access required and what magnitude of load the access cover or grate needs to withstand.

In Australia, requirements for access chamber covers and grates in vehicular and pedestrian areas are covered by Australian Standard AS3996. This standard applies to access covers and grates having openings of up to 1300mm. This standard, or an equivalent standard, is also applicable in other countries such as New Zealand.

AS3996 requires that only surface pits are used in the underground network to provide access to chambers housing fibre optic cables, splices or loops.

AS3996 classifies access chamber covers and grates according to the minimum load able to be withstood. In the Energy Australia network, for example, the minimum requirement for providing access to chambers is Class B. Class B requires a cover or grate to be able to withstand a minimum load of 80 kN (approximately 8000 kg) and applies for use on footpaths where it is possible for a motor vehicle to mount the footpath or for light vehicles, such as park tractors, or livestock to use the pedestrian accessway.

Existing AS3996 Class B (or equivalent) chambers suffer from a number of drawbacks, some of which are: 1 Received at IPONZ on 2 June 2011 • Lack of watertightness, which is problematic when fibre optic or electric cabling is stored in the chamber. The hole through which cabling enters the chamber is often especially prone to leaking water.

• The need to be assembled before they are able to be used. This applies to plastic chambers that have a Class B or higher rating. Assembly takes time and may be difficult to do at an onsite location in adverse conditions.

• Weight. Many chambers require two people (or at least one very strong person) to be easily carried and manoeuvred into position.

Object of the Invention Objects of the invention include but are not limited to providing an improved access chamber, providing an improved kit of parts for constructing a watertight conduit access chamber or an improved method relating to access chambers.

Alternatively, it is an object to address at least some of the foregoing disadvantages associated with the prior art.

Alternatively, it is an object of the invention to at least provide the public with a useful choice. Summary of the Invention According to a first aspect of the invention, there is provided a plastic access chamber comprising: a body portion of unitary construction comprising a base and at least one wall extending from the base wherein the body portion is configured to receive a removable lid such that a watertight seal is created between the lid and the top of the at least one wall of the body portion, wherein the access chamber has a volume of substantially 0.2m3 and a height of at least substantially 600mm.

In preferred embodiments, the access chamber further comprises at least one port in the wall(s). 2 Received at IPONZ on 2 June 2011 Preferably, the at least one wall comprises a plurality of substantially vertical ribs on an outer surface thereof, the ribs providing resistance to a load acting downwards on the access chamber.

According to a second aspect of the invention, there is provided a plastic access chamber comprising: a body portion of unitary construction comprising a base and at least one wall extending from the base wherein the body portion is configured to receive a removable lid such that a watertight seal is created between the lid and the top of the at least one wall of the body portion, wherein the access chamber further comprises at least one port in the wall(s), the port(s) being adapted to receive a watertight fitting.

Preferably, the at least one wall comprises a plurality of substantially vertical ribs on an outer surface thereof, the ribs providing resistance to a load acting downwards on the access chamber.

Preferab.y, the access chamber has a volume of substantially 0,2m3 and a height of at least substantially 600mm.

According to a third aspect of the invention, there is provided a plastic access chamber comprising: a body portion of unitary construction comprising a base and at least one wall extending from the base wherein the body portion is configured to receive a removable lid such that a watertight seal is created between the lid and the top of the at least one wall of the body portion, wherein the at least one wall comprises a plurality of substantially vertical ribs on an outer surface thereof, the ribs providing resistance to a load acting downwards on the access chamber.

In preferred embodiments, the access chamber further comprises at least one port in the wall(s).

Preferably, the access chamber has a volume of substantially 0.2m3 and a height of at least substantially 600mm.

Preferably, access chambers according to any of the above aspects of the invention further comprise a watertight fitting adapted to be received by the port(s). 3 Received at IPONZ on 2 June 2011 The watertight fitting may comprise a nut and a compression fitting, the nut and compression fitting each comprising an aperture dimensioned to frictionally receive a conduit such that the conduit can enter a port and the combined action of at least the nut and compression fitting create a watertight seal about said conduit. In preferred embodiments, the nut is a male hex backnut.

Preferably, access chambers according to any of the above aspects of the invention are adapted to withstand vertical loads of at least 80kN.

Preferably, access chambers according to any of the above aspects of the invention are adapted to be stackable with like access chambers.

The watertight seal between the body portion and the lid of an access chamber according to the invention is preferably provided by means of a gasket.

Preferably, the access chamber further comprises a lid, which may comprise an outer flanged portion and an inner insert portion.

Preferably, the lid is configured to engage the top of the at least one wall by means of one or more fasteners. For example, the fasteners may be screws or the like.

Preferably, the wall(s) comprise a flange around the top thereof for receiving the fasteners.

The lid may comprise a slip resistant upper surface. For example, the upper surface of the lid may comprise a plurality of upward projections.

Preferably, the body portion comprises at least one substantially flat wall. In a most preferred embodiment, the body portion comprises four substantially flat walls. For example, the body portion may be rectangular in cross-section.

Preferably, the body portion is manufactured by a rotational moulding process.

Preferably, access chambers according to any of the above aspects of the invention further comprise a location and/or identification device. In preferred embodiments, the location device may take the form of an RFID tag. 4 Received at IPONZ on 2 June 2011 According to a fourth aspect of the invention, there is provided a kit of parts for constructing a watertight conduit access chamber, the kit of parts comprising: a plastic access chamber according to one or more of the above aspects of the invention; a removable lid configured to engage the top of the at least one wall of the body portion of the plastic access chamber to create a watertight seal therebetween; a nut; and a compression fitting, wherein the nut and compression fitting each comprise an aperture dimensioned to frictionally receive a conduit such that the conduit can enter an access chamber port and the combined action of at least the nut and compression fitting create a watertight seal about said conduit.

Preferably, the nut is a male hex backnut.

In preferred embodiments, the kit of parts further comprises one or more fasteners for fastening the lid to the body portion of the access chamber.

According to a fifth aspect of the invention, there is provided a method of manufacturing a plastic access chamber comprising the step of: rotationally moulding a body portion of unitary construction comprising a base and at least one wall extending from the base.

Preferably, the method further comprises forming a removable lid configured to engage the top of the at least one wall of the body portion to create a watertight seal therebetween.

According to a sixth aspect of the invention, there is provided a method of forming a watertight seal between a wall of an access chamber and a conduit passing through the wall comprising: inserting the conduit through an aperture in a compression fitting; positioning the conduit through a port in the wall such that a portion of the compression fitting extends through the port; inserting a portion of the conduit on an opposite side of the wall from the compression fitting through an aperture in a nut; and engaging the nut with the compression fitting to create the watertight seal about the conduit.

Received at IPONZ on 2 June 2011 In a preferred embodiment, the nut is positioned on the inside of the access chamber.

The method may further comprise forming at least one port in the wall(s) of the access chamber prior to positioning the conduit therethrough.

Further aspects of the invention, which should be considered in all its novel aspects, will become apparent to those skilled in the art upon reading of the following description which provides at least one example of a practical application of the invention.

Brief Description of the Drawings One or more embodiments of the invention will be described below by way of example only, and without intending to be limiting, with reference to the following drawings, in which: Figure 1 is a perspective view illustration of an access chamber according to an embodiment of the invention; Figure 2 is a cross-sectional view illustration of a watertight fitting between a conduit and an access chamber according to an embodiment of the invention; Figure 3 is a side cross-sectional view illustration of the access chamber shown in Figure 1; Figure 4 is a side schematic view of an access chamber according to an alternative embodiment of the invention; Figure 5 is a top schematic view of an access chamber according to the embodiment of the invention shown in Figure 4; Detailed Description of Preferred Embodiments of the Invention Figure 1 is a perspective view illustration of an access chamber 10 according to an embodiment of the invention. Access chamber 10 comprises body portion 11. Body portion is configured to receive removable lid 12. Body portion 11 is of unitary construction and comprises a base and 6 Received at IPONZ on 2 June 2011 at least one wall extending from the base. In the embodiment shown, body portion 11 is generally rectangular in cross-section and has four substantially flat walls. The base may be correspondingly generally rectangular.

Lid 12 is generally shaped in accordance with body portion 11, so in the embodiment shown in Figure 1, lid 12 is generally rectangular. Lid 12 comprises an outer flanged portion 12a and an inner insert portion 12b. The inner insert portion 12b fits within outer flanged portion 12a to form a watertight seal and may be locked in place relative thereto by means of a locking mechanism, as is known in the art. A gasket may be used between inner insert portion 12b and outer flanged portion 12a to form the watertight seal.

Outer flanged portion 12a is adapted to abut the similarly configured or shaped top of the walls of body portion 11, which may include flange 13 around the top thereof. Fasteners 14 may be used to engage lid 12 with body portion 11 to form a watertight seal therebetween. Fasteners 14 may be screws, nails, bolts, rivets or the like. A gasket may be used between lid 12 and body portion 11 to form the watertight seal, An upper surface of lid 12, for example the upper surface of inner insert portion 12b, is preferably slip resistant to prevent pedestrians, vehicles, animals and the like slipping if they pass over the top of access chamber 10. Any known means by which an upper surface can be made resistant to slipping may be used. In the embodiment shown in Figure 1, the upper surface of lid 12 comprises a plurality of upward projections 19 to give a gripping surface.

In the embodiment shown in Figure 1, body portion 11 comprises a plurality of substantially vertical ribs 15 on its outer surface. Ribs 15 give the access chamber increased strength and resistance to loads acting on the access chamber, particularly loads acting on the access chamber in a downwards and/or inwards direction, and ribs 15 therefore help ensure compliance with the Class B safety standard.

In some embodiments, access chamber 10 comprises at least one port 16 in the walls of body portion 11. Ports 16 allow access chamber 10 to receive conduits 17 and are preferably adapted to receive watertight fittings 18 such that no water is able to enter access chamber 10.

In the embodiment shown in Figure 1, access chamber 10 is surrounded by wire cage 61. Wire cage 61 has dimensions such that it can be positioned around the top of the body portion of 7 Received at IPONZ on 2 June 2011 access chamber 10. In the preferred embodiment shown, cage 61 comprises two levels of two horizontally aligned rings and a number of vertically aligned wires.

Cage 61 may be used as reinforcement for a concrete surround to the access chamber, if such a concrete surround is desirable. A concrete surround may be used, for example, to keep the chamber in place in the eventuality that the water table rises to the surface. In alternative embodiments, a concrete surround may be poured without the use of reinforcing cage 61. In either case, the concrete is preferably poured to cover the join between the body portion of the chamber and the outer flanged portion of the lid, but not the join between the outer flanged portion and the inner insert portion of the lid so the insert is left free to be removed.

Figure 2 is a cross-sectional illustration of a watertight fitting between a conduit 21 and an access chamber 22 according to an embodiment of the invention. Conduit 21 passes through a port 23 in a wall of access chamber 22. Conduit 21 also passes through an aperture in a compression fitting 24, preferably such that there is a frictional fit between the conduit and the compression fitting. A portion of compression fitting 24 extends through port 23 and a nut 25 is engaged with this portion, for example by screwing nut 25 onto a thread on the portion. The combined action of the nut and the compression fitting create a watertight seal about conduit 21 such that no water can enter access chamber 22. In a preferred embodiment of the invention, the nut may be a male hex backnut. One or more gaskets 26 may also be used to enhance the watertight seal if required. Other components may also be used in the watertight fitting.

The use of a compression fitting and nut is advantageously able to be used with plastic access chambers with walls having a thickness approproate to receive suitable compression fittings. Many existing concrete chambers are unsuited to the use of a compression fitting and nut combination because the concrete walls are too thick and foaming resins are used to fill the roughly cut holes in the sides of the concrete walls. If plastic chambers have a thickness that is larger than the size of the compression fitting, the combination again cannot be used.

The ports in the walls of the access chamber may be pre-made or alternatively they may be made on site to suit the precise location in the walls required for a conduit to pass into the access chamber. Embodiments in which the walls of the access chamber are substantially flat may provide an advantage because many types of conduit fitting are better suited to provide a watertight seal if the wall is substantially flat. 8 Received at IPONZ on 2 June 2011 Figure 3 is a side cross-sectional view illustration of access chamber 10 shown in Figure 1. Figure 3 illustrates a coil of fibre optic cable 71 and a vertical splice closure mounting 72 housed inside access chamber 10. As will be discussed in further detail below, access chamber 10 has dimensions such that it can house equipment like cable 71 and splice 72 and have the necessary strength for Class B classification.

Figures 4 and 5 are side and top schematic views respectively of an access chamber 30 according to an alternative embodiment of the invention. Figures 4 and 5 indicate exemplary dimensions of an access chamber according to an embodiment the invention. Access chamber 30 preferably has a height of substantially 900mm and at least substantially 600mm. Access chamber 30 has a width of substantially 760mm and is approximately square in cross-section. Access chamber 30 has a total chamber volume of substantially 0.2m3.

The dimensions of the access chamber are an important balance between space and strength requirements. On the one hand, an access chamber must be large enough to meet the curvature requirements of cables to be stored in the chamber. For example, fibre optic cables cannot be bent too tightly or their ability to efficiently transmit light is adversely affected. Therefore, access chambers need to have a corresponding minimum size. Furthermore, when plastic is used to construct the access chamber, an overly large chamber is less able to support the space under a Class B loading on the lid. In some cases, cement or other reinforcing materials may be required, which increase the complexity of the chamber construction. The dimensions discussed above have therefore been carefully selected to ensure a one-piece plastic chamber can support a Class B loading while still providing enough room for fibre optic cables to be stored inside.

It has been found that when an access chamber is constructed using preferred materials according to the approximate dimensions identified above and in the figures, the access chamber has sufficient strength to withstand the forces likely to be exerted on it in use and the chamber also has the appropriate dimensions for it to be able to store conduits, cables, splices, loops and the like, and still provide reasonable access to an engineer. Embodiments in which the walls are reinforced with ribs have been found to be particularly strong. In particularly, the access chamber is able to withstand vertical loads of at least 80kN, meaning it is able to support a lid classified in Class B according to AS3996. 9 Received at IPONZ on 2 June 2011 Preferred materials for constructing an access chamber according to an embodiment of the invention are plastics materials. This provides advantageous properties of strength, durability and weight. In a preferred embodiment of the invention, the access chamber weighs no more than approximately 35kg and can therefore be comfortably carried by one or two people to reduce installation labour costs.

In a preferred embodiment of the invention, the body portion of the access chamber is manufactured by a rotational moulding process such that the body portion comprising the base and wall(s) are of a unitary construction, which helps increase the strength of the body portion. The lid may be formed by any suitable moulding process known to those of skill in the art.

In one embodiment of the invention the access chamber body portions are configured such that several access chamber body portions can be stacked together to save space for transportation and/or storage purposes. For example, body portions may have grooves on the inner surfaces of the walls to compliment the ribs on the outer surfaces of the walls such that, when stacked, the ribs fit inside the grooves.

Use and Installation of an Access Chamber In use, an access chamber according to the invention is adapted to be positioned in a pit in the ground such that the chamber can provide access to underground installations by removing its lid. The access chamber is preferably positioned such that the lid is substantially flush with the surface of the surrounding ground as is common with access chambers. Access chambers according to the invention are suited to support lids classified in Class B of AS3996, meaning they are suited to footpath and roadside locations.

Access chambers according to the invention are generally suitable for providing access to a variety of cables and conduits, including fibre optic cables, splices and loops. They may be suited to micro trenching, direct burial and air blown cable applications.

The unitary construction of the body portion of access chambers according to the invention provides an advantage over many prior art access chambers that must be put together on site, thus wasting valuable time.

Received at IPONZ on 2 June 2011 As mentioned above, the ports in the wall(s) of the access chamber can be made during the manufacturing process, in advance of installation or during installation using, for example, a drill or cutting device, depending on requirements. Often, cables are not laid in the ground at uniform depths so it is advantageous to be able to choose where the ports are located during installation. For example, fittings may be required at depths as shallow as 200mm or as deep as 700mm. In addition, the number of ports that are required and the walls on which they are required may not be known until installation.

With reference to Figure 2, there will now be described the method by which a watertight seal can be formed between the wall of access chamber 22 and conduit 21. The conduit is inserted through an aperture in compression fitting 24. Conduit 21 and compression fitting 24 are subsequently positioned through port 23 such that a portion of compression fitting 24 extends through port 23. A portion of the conduit on the opposite side of the access chamber wall to compression fitting 24 is inserted through an aperture in a nut 25, such as a male hex backnut. Finally, nut 25 is engaged with compression fitting 24 to create a watertight seal about conduit 21, for example by screwing nut 25 onto a thread on compression fitting 24.

In preferred embodiments, nut 25 is positioned on the inside of access chamber 22 as shown in Figure 2.

Alternative Embodiments of the Invention In other embodiments, the body portion of the access chamber may have differing cross-sectional shapes. For example, in one embodiment the body portion may comprise one wall such that the body portion is generally circular in cross-section, which has the benefit of increased strength compared to, for example, a rectangular cross-section, but may be more problematic for attaching a conduit fitting with a watertight seal to the access chamber.

In one embodiment of the invention, the access chamber comprises a location and/or identification device enabling the access chamber to be located and/or identified, preferably remotely. For example, the access chamber may comprise an RFID tag. Such a tag may be located anywhere around the access chamber, but locating the tag within the access chamber enables the tag to be kept reasonably dry when the access chamber is in use. Also, locating the tag near the lid enhances its ability to send/receive RF signals with a transmitter/receiver located above ground. 11 Received at IPONZ on 2 June 2011 Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise", "comprising", and the like, are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense, that is to say, in the sense of "including, but not limited to".

The entire disclosures of all applications, patents and publications cited above and below, if any, are herein incorporated by reference.

Reference to any prior art in this specification is not, and should not be taken as, an acknowledgement or any form of suggestion that that prior art forms part of the common general knowledge in the field of endeavour in any country in the world.

The invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, in any or all combinations of two or more of said parts, elements or features.

Where in the foregoing description reference has been made to integers or components having known equivalents thereof, those integers are herein incorporated as if individually set forth.

It should be noted that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the spirit and scope of the invention and without diminishing its attendant advantages. It is therefore intended that such changes and modifications be included within the present invention. 12 Received at IPONZ on 2 June 2011

Claims (26)

Claims

1. A plastic access chamber comprising: a body portion of unitary construction comprising a base and at least one wall extending from the base wherein the body portion is configured to receive a removable lid such that a watertight seal is created between the lid and the top of the at least one wall of the body portion, wherein the body portion comprises at least one port in the wall(s), the port(s) being adapted to receive a watertight fitting; and a watertight fitting comprising a nut and a compression fitting, the nut and compression fitting each comprising an aperture dimensioned to frictionally receive a conduit such that the conduit can enter a port and the combined action of at least the nut and compression fitting create a watertight seal about said conduit.

2. A plastic access chamber as claimed in claim 1, wherein the at least one wall comprises a plurality of substantially vertical ribs on an outer surface thereof, the ribs providing resistance to a load acting downwards on the access chamber.

3. A plastic access chamber as claimed in any one of claims 1-2, wherein the access chamber has a volume of substantially 0.2m3 and a height of at least substantially 600mm.

4. A plastic access chamber as claimed in any one of claims 1-3, wherein the nut is a male hex backnut.

5. A plastic access chamber as claimed in any one of claims 1-4, wherein the access chamber is adapted to withstand vertical loads of at least 80kN.

6. A plastic access chamber as claimed in any one of claims 1-5, wherein the access chamber is adapted to be stackable with like access chambers.

7. A plastic access chamber as claimed in any one of claims 1-6, wherein the body portion comprises a gasket adapted to receive the removable lid to form the watertight seal.

8. A plastic access chamber as claimed in any one of claims 1-7, wherein the access chamber further comprises a lid. 13 Received at IPONZ on 2 June 2011

9. A plastic access chamber as claimed in claim 8, wherein the lid comprises an outer flanged portion and an inner insert portion.

10. A plastic access chamber as claimed in any one of claims 8-9, wherein the lid is configured to engage the top of the at least one wall by means of one or more fasteners.

11. A plastic access chamber as claimed in claim 10, wherein the fasteners are screws or the like.

12. A plastic access chamber as claimed in any one of claims 10-11, wherein the wall(s) comprise a flange around the top thereof for receiving the fasteners.

13. A plastic access chamber as claimed in any one of claims 8-12, wherein the lid comprises a slip resistant upper surface.

14. A plastic access chamber as claimed in any one of claims 1-13, wherein the body portion comprises at least one substantially flat wall.

15. A plastic access chamber as claimed in claim 14, wherein the body portion comprises four substantially flat walls.

16. A plastic access chamber as claimed in any one of claims 1-15, wherein the body portion is manufactured by a rotational moulding process.

17. A plastic access chamber as claimed in any one of claims 1-16, wherein the access chamber further comprises a location and/or identification device.

18. A plastic access chamber as claimed in claim 17, wherein the location device is an RFID tag.

19. A kit of parts for constructing a watertight conduit access chamber, the kit of parts comprising: a plastic access chamber as claimed in any one of claims 1-18; a removable lid configured to engage the top of the at least one wall of the body portion of the plastic access chamber to create a watertight seal therebetween; a nut; and 14 Received at IPONZ on 2 June 2011 a compression fitting, wherein the nut and compression fitting each comprise an aperture dimensioned to frictionally receive a conduit such that the conduit can enter an access chamber port and the combined action of at least the nut and compression fitting create a watertight seal about said conduit.

20. A kit of parts as claimed in claim 19, wherein the nut is a male hex backnut.

21. A kit of parts as claimed in any one of claims 19-20, wherein the kit of parts further comprises one or more fasteners for fastening the lid to the body portion of the access chamber.

22. A method of forming a watertight seal between a wall of an access chamber and a conduit passing through the wall comprising: inserting the conduit through an aperture in a compression fitting; positioning the conduit through a port in the wall such that a portion of the compression fitting extends through the port; inserting a portion of the conduit on an opposite side of the wall from the compression fitting through an aperture in a nut; and engaging the nut with the compression fitting to create the watertight seal about the conduit.

23. A method as claimed in claim 22, wherein the nut is positioned on the inside of the access chamber.

24. A method as claimed in any one of claims 22-23, wherein the method further comprises forming at least one port in the wall(s) of the access chamber prior to positioning the conduit therethrough.

25. A plastic access chamber substantially as hereinbefore described with reference to any one of the embodiments shown in the figures.

26. A kit of parts for constructing a watertight conduit access chamber substantially as hereinbefore described with reference to any one of the embodiments shown in the figures. 15 Received at IPONZ on 2 June 2011 A method of forming a watertight seal between a wall of an access chamber and a conduit passing through the wall substantially as hereinbefore described with reference to any one of the embodiments shown in the figures. 16