GB2126262A

GB2126262A - Inspection chambers for drainage systems

Info

Publication number: GB2126262A
Application number: GB08314066A
Authority: GB
Inventors: John David Carpenter
Original assignee: Paragon Plastics Ltd
Current assignee: Paragon Plastics Ltd
Priority date: 1982-08-26
Filing date: 1983-05-20
Publication date: 1984-03-21
Also published as: GB8314066D0; GB2126262B

Abstract

In a synthetic plastics inspection chamber having an integral or attached closed base with inlet, outlet and branch connections such as 14, 32, 30 and an upstanding main body 10 of square or other cross-section, the upstanding main body 10 has a number of vertically spaced corrugations 34 so as to be capable of concertina-like movements. The inspection chamber is thus able to withstand ground movement without being damaged. <IMAGE>

Description

SPECIFICATION inspection chambers for drainage systems The invention relates to inspection chambers for drainage and sewerage systems, that is to say to inspection chambers which allow access from ground level to such systems.

Inspection chambers have in the past been constructed on site of pre-formed concrete sections or formed of brick or concrete or a combination of both. Because of the need to make such chambers waterproof they must be carefully constructed of high quality materials.

Consequently, they are of high cost.

In a previous attempt to overcome this problem there has been provided a synthetic plastics inspection chamber of prefabricated construction, the chamber comprising a cylindrical or polygonally shaped member having an integral closed base in which is formed an upwardly open channel communicating with inlet and outlet pipes extending outwardly from the cylindrical or polygonally shaped member, as the case may be.Such a chamber has been relatively inexpensive to produce but has been prone to one particular drawback, this being that when the chamber has been installed and the upper end of the cylindrical or polygonally shaped member has been set in concrete, any subsequent ground movement has stressed the side walls of the chamber to such an extent that they have sometimes become cracked or deformed or to such an extent that excessive stresses have been applied to the connecting pipework or joints so that cracking or deformation of such pipework or joints has resulted and subsequent leakage has been caused. The object of the invention is to provide a synthetic plastics inspection chamber which will withstand ground movement without being damaged.

According to the invention, there is provided an inspection chamber for a drainage system, the chamber being made of synthetic plastics material and having an upstanding main body of cylindrical or multi-sided shape in a lowermost portion of which a plurality of inlet connections and a single outlet connection are formed, the upstanding main body being provided with a plurality of vertically spaced configurations extending around it and by virtue of which, when the inspection chamber is in use, the body part is capable of a concertina-like movement to withstand ground movement without being damaged.The plurality of vertically spaced configurations extending around the upstanding main body will preferably be vertically spaced enlargements, the wall thickness of the enlargements being the same, or substantially the same, as the general wall thickness of the main body so that, in effect, the main body is provided with a plurality of outwardly stepped portions.

Preferably, also, an integral closed base of the main body will be formed with an upwardly open channel extending across it, this constituting a main drainage channel communicating at one end with a main inlet connection and at the other end with the outlet connection.

In order that the invention may be fully understood and readily carried into effect, the same will now be described, by way of example only with reference to the accompanying drawings, of which: Fig. 1 is a side view of a synthetic plastics inspection chamber embodying the invention, Fig. 2 is an end view, Fig.3 is a plan view, Fig. 4 is a sectional view on the line 4-4 in Fig. 2, and Fig. 5 is a sectional scrap view on the line 5-5 in Fig. 1, drawn to a somewhat larger scale than the other views.

Referring now to the drawings, the inspection chamber there illustrated is a one-piece moulding in a synthetic plastics material and has an upstanding main body generally indicated 10, which in this instance is shown to be of square cross section. A closed base of the main body (shown in this instance to have been formed integrally with the main body) is formed with an upwardly open channel 12 of half round shape extending across it between two opposite sides, this constituting a main drainage channel which communicates at one end with a main inlet connection 14 and at the other end with an outlet connection 1 6. As shown in Fig. 1, there is a very slight "fall" between the inlet and outlet connections.The lower part of the main body is also provided with four branch channels 1 8, 20, 22 and 24 which communicate with respective connections 26, 28, 30 and 32, the connections 26 and 28 extending from opposite side surfaces of the body and the connections 30 and 32 extending through the corners of the body at the upstream side of the chamber.

The main body of the chamber is provided above a lowermost portion through which the various connections extend, with a plurality of vertically spaced enlargements 34 which extend around the four sides of said body. However, the wall thickness of the enlargements is the same as the general wall thickness of the body and the arrangement is such that, as shown in Fig. 5, the body part is provided with outwardly stepped portions by virtue of which the body part as a whole is capable of a very slight concertina-like movement throughout its entire depth.

It has been found that the inspection chamber just described, when in use, has been able to withstand considerable ground movement without being damaged, this being due to the fact that the body part has been capable of the very slight concertina-like movement referred to, allowing both vertical and lateral movement of its upper end portion relative to the lowermost portions into which the various connections have been made. However, various modifications may be made. For example, it may be found that the main body can have a greater or lesser number of vertically spaced enlargements 34. It will also be understood that the cross sectional shape in the region of each enlargement may be different. For example, if a greater number of the enlargements are provided, it may be found that the lateral stepping required at each enlargement is correspondingly less. All these variables can of course be determined by experiment for optimum results. It will also be understood that instead of being provided with enlargements, the upstanding main body could be provided with oppositely facing but very similar configurations, that is to say a plurality of vertically spaced deep grooves in its outer surface. Instead of being of square section, the upstanding main body could be of any other multisided shape or alternatively could be of cylindrical or elliptical shape. Instead of being formed integrally with the main body, the base could be formed separately and subsequently joined to the upstanding main body.

Claims

1. An inspection chamber for a drainage system, the chamber being made of synthetic plastics material and having an upstanding main body of cylindrical or multi-sided shape in a lowermost portion of which a plurality of inlet connections and a single outlet connection are formed, the upstanding main body being provided with a plurality of vertically spaced configurations extending around it and by virtue of which when the inspection chamber is in use, the body part is capable of a concertina-like movement to withstand ground movement without being damaged.

2. An inspection chamber according to claim 1, in which the plurality of vertically spaced configurations extending around the upstanding main body are vertically spaced enlargements, the wall thickness of the enlargements being the same, or substantially the same, as the general wall thickness of the main body so that, in effect, the main body is provided with a plurality of outwardly stepped portions.

3. An inspection chamber according to either one of the preceding claims, in which an integral closed base of the main body is formed with an upwardly open channel extending across it, this constituting a main drainage channel communicating at one end with a main inlet connection and at the other end with the outlet connection.

4. An inspection chamber constructed, arranged and adapted to be used substantially as hereinbefore described with reference to and as illustrated by the accompanying drawings.