NZ204258A - Plastics manhole chamber with channelled base,multiple side openings,and a flange sheltered spigot and socket joint with a side wall extension - Google Patents

Description

204258 Priority Date(s): f?/.

Complete Specification Filed: Class: OO^' ?7/2,' i '4''''''" "' Publication Date: ..,, 11 198*5 ;I P.O. Journal, No: ;*—i—■■ N.Z.No.

NEW ZEALAND Patents Act 1953 COMPLETE SPECIFICATION "INSPECTION CHAMBER." We, THE HEPWORTH IRON COMPANY LIMITED, a British Company of Hazlehead, Stocksbridge, Sheffield, England do 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 : - (Followed by 1A.) MAY 1983^] Efciv«52 ' n -i 1ft- This invention relates to inspection chambers (which expression also includes manholes) for use in drainage or sewerage systems and has for its object the provision of a standard manhole access chamber readily adaptable to a wide variety of drainage pipe layouts at a wide variety of depths below ground level.

Such inspection chambers are described in GB-PS 1192650; 1272039; 1447227; 1568364; 1577986 and 1577987 as comprising a plastics base portion with a bottom integral with a side wall, the bottom having a main channel extending between two side openings for connection to drain pipes and a plurality of further side openings for connection to drain pipes and leading into secondary channels discharging into the main channel, together with at least one generally cylindrical plastics extension portion connected to the side wall of the base portion by means of a spigot and socket joint and preferably bonded or otherwise sealed. The upper end of the extension portion may be fitted with a frame for a lid (or manhole cover) or it may be fitted with one or more similar plastics extension portions, with the upper end of the uppermost extension portion fitted with a frame for a lid. 2 In use, the plastics inspection chamber may be set in concrete in the ground or have aggregate packed in between it and a hole in the ground, but whatever method is used the side wall and the extension portion or portions must have adequate stiffness to prevent distortion. It is known, therefore, to make the extension portion (or each extension portion) thick enough to accommodate a rebate or socket, which fits over the upper edge of the base portion or another extension portion, within a plain, substantially cylindrical external and internal shape. The extension portion being made of glass-fibre reinforced plastics (GRP), but this extension has been replaced for cost reasons by an unreinforced plastics one made of polyvinylchloride (PVC) with a plurality of circumferential strengthening ribs at intervals over its height and an enlarged socket region at the bottom. However, the circumferential ribs and enlarged socket cause complications in manufacture because of the need for split moulds, and the ribs limit the positions at which the extension can be cut in order to provide an inspection chamber of a desired total height. It is an object of the present invention to avoid these complications. 204558 According to the present invention, an inspection chamber comprises a plastics material base portion with a bottom and an integral upstanding side wall, the bottom having a main channel extending between two side openings for connection to drain pipes and a plurality of further side openings for connection to drain pipes and leading into secondary channels discharging into the main channel, together with at least one substantially cylindrical plastics material extension portion onfaffigod, in use, with the upper end of the side wall of the base portion or of a lower such extension portion by means of a spigot and socket joint, the lower end of the or each extension portion having an integral circumferential flange extending first outwardly from just above the joint and then downwardly overlapping the joint, and a plurality of radial webs being provided between the lower and inner faces respectively of the outward and downward parts of the flange.

This construction of the extension portion lends itself to injection moulding between simple axially separable mould parts, with one mould part defining the cylindrical outer form of the extension and the upper and outer faces respectively of the outwardly and downwardly extending parts of the flange, and with the other mould part defining the lower and inner faces respectively of the outward and downward parts of the JUNI9SO flange and the faces and edges of the radial webs. Each 4 mould part also forms a respective joint part and is preferably provided with a plug or core portion forming half the inside of the extension with a slight taper allowing "draw" of the mould parts. This construction also lends itself to manufacture in polypropylene, the thickness of which can be kept substantially constant throughout the extension portion, the joint part, the flange parts, and the webs. The "hooked" flange hides the joint line of the spigot and socket joint from immediate view, and so leads to a pleasing appearance, especially when more than one such extension portion is provided, it also protects the joint region by externally overlapping it as well as by stiffening it. The outward part of the. flange is preferably perpendicular to the axis of the extension portion and the downward part is parallel to the axis.

The lower end of the or each extension portion is preferably formed with the spigot part of the joint, there being a radial gap between at least the lower part of each web and the spigot part to accommodate at least the upper part of the socket part of the joint, which is on the upper end of the side wall of the base portion or on the upper end of a lower extension portion, and the lower inner corner of each web, remote from both parts of the flange, is preferably bevelled or rounded to provide a lead-in for the socket part of the joint. 204258 The extension portion or the uppermost extension portion can be cut across at any level to provide a chamber of any precise desired overall height.

Preferably there is provided a frame for a lid to be located on the upper edge (whether a cut edge or not), having a downwardly facing circumferential channel in the frame to fit over the said edge and of a radial width sufficient for it to fit over the flange of a cut extension portion where the distance from the cut end to the outwardly extending part of the flange is less than the depth of the channel in the frame.

The means for connection of each side opening to a drain pipe preferably consists of a circular pipe portion integral with the base portion and extending outwardly from the side wall, the end of each pipe portion remote from the side wall being provided with an inwardly projecting circumferential sealing ring sealed to the pipe portion, e.g., by being bonded thereto or secured thereon by a snap-on locking ring.

In accordance with established marketing practice, a chamber in accordance with the invention is preferably supplied with stoppers closing all the side openings, except for the side opening that is at the outlet end of the main channel, one or more stoppers being removed on site to enable the or each required side opening to be connected to a drainpipe, in addition to the drainpipe connected to the outlet opening. 6 An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which Figure 1 is a small scale side elevation of an inspection chamber in accordance with the invention; Figure 2 is a plan of the chamber of Figure 1; Figure 3 is a vertical section taken from the line A-A of Figure 2; Figure 4 is a horizontal section taken from the line B-B of Figure 1; Figure 5 is an enlarged fragmentary section corresponding to part of Figure 3; and Figure.6 corresponds to part of Figure 5 but shows a frame for a lid located on a cut edge of the chamber.

In the drawings, an inspection chamber comprises a plastics base portion 10 with a bottom 11 integral with an upstanding side wall 12, the bottom having a main channel 13 extending between two circular side openings 14, 15 with pipe portions 16 ending in sealing rings 17. secured by snap-on locking rings 18 to form sockets for drain pipes (not shown), and four further circular side openings 19 (with pipe portions 16, sealing rings 17 and locking rings 18) leading into secondary channels 20 discharging into the main channel 13, together with a generally cylindrical plastics extension portion 21 connected to the side wall 12 of the base portion 10 by 7 means of a spigot and socket joint 22, 23 bonded or otherwise sealed, the spigot 22 being on the lower end of the extension and the socket 23 on the upper end of the side wall 12. The lower end of the (or each) extension portion 21 has an integral circumferential protective and reinforcing flange 24 extending first outwardly (perpendicular to the vertical axis of the extension) from just above the joint and then downwardly (parallel to the axis) substantially over the height of the joint to overlap the joint line, and a plurality of radial webs 25 between the lower and inner faces 26, 27 respectively of the outward and downward parts 28,. 29 of the flange, and between these faces and the wall of the extension. The corner 30 of each web 25 remote from the parts 28, 29 of the flange 24 is rounded to provide a lead-in for the socket part 23 of the joint. The upper end of the extension portion 21 is provided with a socket part 31 for fitting another similar extension portion if necessary to afford the required overall height of the chamber.

The base portion 10 and the extension portion 21 are preferably made of polypropylene. The extension portion because it has only a single lateral projection, can be injection moulded between simple axially separable moulds (not shown), with one mould defining the plain cylindrical outer form of the extension, the upper and 8 outer faces 32, 33 respectively of the flange parts 28, 29, and (by means of a plug portion) the inner form of the socket 31 and upper half of the inner form of the socket 31 and upper half of the inner form of the extension with a slight taper allowing "draw" of the mould; and with the other mould defining the outer form of the spigot 22, the lower and inner faces 26, 27 respectively of the flange parts 28, 29, the faces and edges of the radial webs 25, and (by means of a plug portion) the lower half of the inner form of the extension with a slight taper allowing "draw" of the mould.

The extension portion 21 (or the uppermost extension portion), because it is a plain cylinder, can be cut across at any level (see Figure 6) to provide a chamber of any precise desired overall height, and a frame 34 for a lid (not shown) is located on the upper edge (whether a cut edge or not). Because the reinforcing and protecting flange is at the bottom of the extension, cutting off the top of the extension leaves the flange unaffected.

The lid frame 34 has a downwardly facing circumferential channel 35 which is seated on the upper edge of the extensions and is wide enough to fit over the flange 24 of the cut extension if the cut be closer to the flange than the depth of the channel 35 in the frame.

Claims (10)

WHAT WE CLAIM IS;

1. An inspection chamber comprising a plastics material base portion with a bottom and an integral upstanding side wall, the bottom having a main channel extending between two side openings for connection to drain pipes and a plurality of further side openings for connection to drain pipes and leading into secondary channels discharging into the main channel, together with at least one substantially cylindrical plastics material extension portion offigumgod, i,n use. with the upper end of the side wall of the base portion or of a lower such extension portion by means of a spigot and socket joint, the lower end of the or each extension portion having an integral circumferential flange extending first outwardly from just above the joint and then downwardly overlapping the joint, and a plurality of radial webs being provided between the lower and inner faces respectively of the outward and downward parts of the flange.

2. An inspection chamber as in claim 1, manufactured in polypropylene.

3. An inspection chamber as in claim 1 or claim 2, wherein the outwardly extending part of the flange is perpendicular to the axis of the extension portion and the downwardly extending part is parallel to the axis. 20 4-258 10

4. An inspection chamber as in any one.of the preceding claims, wherein the lower end of the or each extension portion is formed with the spigot part of the joint, there being a radial gap between at least part of each web and the spigot part to accommodate at least the upper part of the socket part of the joint, which is on the upper end of the side wall of the base portion or on the upper end of a lower extension portion.

5. An inspection chamber as in claim 4, wherein corner of each web remote from both parts of the flange is bevelled or rounded to provide a lead-in for the socket part of the joint.

6. An inspection chamber as in any one of the preceding claims, wherein a frame for a lid is located on the upper edge of the extension portion or of the uppermost extension portion by means of a downwardly facing circumferential channel in the frame which channel is of r6rit a radial width sufficient I to fit over the flange of a cut extension portion where the distance from the cut end to the outwardly extending part of the flange is less than the depth of the channel in the frame.

7.T An inspection chamber as in any one of the preceding claims, including for connection of each side opening to drain pipe a pipe portion integral with the base ,jui1*'7w*n/J>ortion and extending outwardly from the side wall, the 20 A 1 K 11 end of each pipe portion remote from the side wall being provided with an inwardly projecting circumferential sealing ring sealed to the pipe portion.

8. An inspection chamber as in any one of the preceding claims with stoppers closing all the side openings, except for the side opening that is at the outlet end of the main channel.

9. An inspection chamber substantially as hereinbefore described with reference to Figures 1 to 5 of the accompanying drawings.

10. An inspection chamber as in claim 9 provided with a frame for a lid substantially as hereinbefore described with reference to Figure 6 of the accompanying drawings. THE HEPWORTH IRON COMPANY LIMITED By Their Attorneys HENRY HUGHES LIMITED By: