GB2120698A

GB2120698A - Drainage inspection chamber

Info

Publication number: GB2120698A
Application number: GB08214881A
Authority: GB
Inventors: John Benjamin Glover; Colin Adie
Original assignee: Hepworth Iron Co Ltd
Current assignee: Hepworth Iron Co Ltd
Priority date: 1982-05-21
Filing date: 1982-05-21
Publication date: 1983-12-07
Also published as: NZ204258A; ZA833648B; AU554583B2; GB2120698B; AU1455383A

Abstract

A multi-way drainage inspection chamber has the side wall (12) of its polypropylene base portion (10) connected to a polypropylene extension portion (21) by means of a spigot and socket joint (22, 23) bonded or otherwise sealed, the lower end of the extension portion (21) having a flange (24) with outward and downward parts (28, 29) stiffened by webs (25), the spigot part (22) preferably being on the extension portion (21) so that a gap is needed between the spigot (22) and the webs (25) to receive the socket part (23), and the corners (30) of the webs (25) remote from both parts (28, 29) of the flange (24) are bevelled or rounded to provide a lead-in for the socket part (23). The hooked and webbed flange (24) both hides the spigot and socket joint (22, 23) and also affords adequate stiffness for the extension portion (21), whilst being simple to mould. <IMAGE>

Description

SPECIFICATION Inspection chamber 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; 1 577986 and 1577978 as comprising a plastics base portion with a bottom integral with a side wall, the bottom having a main channel extending between two circular side openings with means for connection to drain pipes and a plurality of further circular side openings with means 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.

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, for connection to the base portion or another extension portion, within a plain, substantially cylindrical external and internal shape. Such an extension portion has been made of glass-fibre reinforced plastics (GRP), but has been substituted for cost reasons by an unreinforced plastics one made of polyvinylchloride (PVC) with a plurality of circumferential ribs at intervals over its height.

However, the circumferential ribs cause complications in manufacture because of the need for split moulds, and it is the object of the present invention to overcome these complications.

According to the present invention, therefore, an inspection chamber comprises a plastics base portion with a bottom integral with a side wall, the bottom having a main channel extending between two circular side openings with means for connection to drain pipes and a plurality of further circular side openings with means 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, 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 substantially over the height of 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 moulds, with one mould defining the cylindrical outerform of the extension and the upper and outer faces respectively of the outward and downward parts of the flange, and with the other mould defining the lower and inner faces respectively of the outward and downward parts of the flange and the faces and edges of the radial webs. Each mould also forms a respective joint part and is preferably provided with a plug portion forming half the inside of the extension with a slight taper allowing "draw" of the moulds. 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 spigot and socket joint from immediate view, and so leads to a pleasing appearance, especially when more than one such extension portion is provided. 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 gap between at least part of each web and the spigot part to accommodate at least 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 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.

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, and a frame for a lid is preferably located on the upper edge (whether a cut edge or not) by means of a downwardly facing circumferential channel in the frame of a radial width sufficient to fit over the flange of a cut extension portion if the cut be closer to the flange than the depth of the channel in the frame.

The means for connection of each circular side opening to a drain pipe preferably consists of a 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 sealded 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 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.

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 a side wall 12, the bottom having a main channel 1 3 extending between two circular side openings 14, 1 5 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 1 9 (with pipe portions 16, sealing rings 1 7 and locking rings 18) leading into secondary channels 20 discharging into the main channel 1 3, together with at least the one generally cylindrical plastics extension portion 21 connected to the side wall 12 of the base portion 10 by means of a spigot and socket joint 22, 23 bonded or otherwise sealed, the lower end of the (or each) extension portion 21 having an integral circumferential flange 24 extending first outwardly from just above the joint and then downwardly substantially over the height of the joint, and a plurality of radial webs 25 being provided between the lower and inner faces 26, 27 respectively of the outward and downward parts 28, 29 of the flange. 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 overall height of the chamber required.

The base portion 10 and the extension portion 21 are preferably made of polypropylene; and the extension portion is injection moulded between simple axially separable moulds (not shown); with one mould defining the cylindrical outer form of the extension, the upper and 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 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) 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) by means of a downwardly facing circumferential channel 35 in the frame of a radial width sufficient to fit over the flange 24 of the cut extension if the cut be closer to the flange than the depth of the channel in the frame.

Claims

1 An inspection chamber comprising a plastics base portion with a bottom integral with a side wall, the bottom having a main channel extending between two circular side openings with means for connection to drain pipes and a plurality of further circular side openings with means 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 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 substantially over the height of 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 outward part of the flange is perpendicular to the axis of the extension portion and the downward part is parallel to the axis.

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 gap between at least part of each web and the spigot part to accommodate at least 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 the 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 of a radial width sufficient to fit over the flange of a cut extension portion if the cut be closer to the flange than the depth of the channel in the frame.

7. An inspection chamber as in any one of the preceding Claims, wherein the means for connection of each circular side opening to a drain pipe consists of a 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 and 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 7 provided with a frame for a lid substantially as hereinbefore described with reference to Figure 6 of the accompanying drawings.