GB2099877A - Inspection chambers - Google Patents

Abstract

A plastics drainage access bowl 10 has a bottom outlet 12 and a number of inlets 14 in its hemispherical or conical wall which are formed in an injection moulding process. The bowl is supplied to the customer with removable snap-in covers 15 for all but one inlet, which covers are shaped to conform with the internal surface of the bowl. Plastics inlet connections (not shown) may be cemented to the outside of the bowl. <IMAGE>

Description

SPECIFICATION Drainage access bowl This invention relates to drainage access bowls.

Such items are typically now made of plastics material and comprise a generally hemi-spherical or conical bowl portion with an outlet at the base of the bowl portion, and an inlet part way up the wall of the bowl. In use, the bowl is positioned and supported in the ground so that its basal outlet connects with a principal underground drain line and its inlet can be connected to a drainage pipe running at a higher level than the principal drain line. The bowl can be connected to the end of or in the run of a principal underground drain line, and may have an inter-connecting pipe from its basal outlet to the principal drain line.

An example of a previously proposed drainage access bowl is described in British Patent Specification No 1 297 562 and it can be seen that its principal purposes are to permit inspection of the flow from the drainage pipe to the principal drain line, and also to enable rodding devices to be inserted into the outlet from the bowl or into the principal drain line to clear blockages. The use of an access bowl, with a suitable frame and cover, avoids the need for traditionally constructed, and more expensive, drainage manhole accesses.

It is an object of the invention to provide an improved construction of drainage access bowl, the particular advantages of which will become apparent from the description of the embodiment described hereinafter.

The invention provides a drainage access bowl having a curved interior surface, a basal outlet, and a plurality of inlets spaced upwardly in the side of the bowl from the basal outlet, one or more of said inlets being provided with a removable cover.

The curved interior surface of the bowl may form part of a sphere, eg it may be of hemispherical shape. Alternatively, the interior surface could be conical, extending to an apparent apex below or in the basal outlet.

The inlets may be symmetrically located around the bowl, and there may be four such inlets, three of which are provided with a removable cover. The perimeters of the inlets may be circular in shape and all the inlets may be of the same size.

The removable cover may be shaped so that its inner surface conforms substantially to the inner surface of the bowl eg if the bowl is hemispherical, then the inner surface of the cover may be shaped as part of a hemisphere. The cover may be removable from the inside of the bowl by the application of pressure to the central region of the cover. It is preferably made of flexible or elastomeric plastics material eg polypropylene and suitably engages the perimeter of the inlet by means of two integrally formed lugs on the convex side of the cover. The cover may be removed by pressing the central region of the flexible cover to disengage the lugs from the perimeter of the inlet. At least one of these engaging lugs may be shaped as half of an arrow head ie split down the axis of symmetry of an arrow head when seen in cross-section extending from the cover.The engaging lugs may be formed diametrically opposite one another on the cover.

One or more additional lugs may be integrally moulded on the same side of the cover as the engaging lugs, which additional lugs are adapted to locate the cover with respect to the perimeter of the inlet.

One embodiment of the invention will now be described, by way of example oniy, with reference Ao the accompanying drawings, in which: Figure 1 is an elevation in cross-section of an access bowl according to the invention, Figure 2 shows an enlarged detail of the access bowl of Figure 1, and Figure 3 is a cross-sectional view on line Ill-Ill of Figure 2.

The access bowl 10 shown in Figure 1 is made of plastics material, typically by injection moulding. The bowl 10 comprises a thin-walled hemi-spherical portion 11 with an outlet 12 at its lower end and a lip 13 at its upper edge to assist in location in a concrete surround (not shown) and to provide location for a lid or distance piece (not shown).

Symmetrically spaced around the wall of the hemi-spherical portion 11 are four inlets 14, each having a circular perimeter and each being of the same diameter. Plastics inlet connections (not shown) may be attached by solvent cement to the wall of the hemi-spherical portion 11 adjacent the perimeter of each inlet, such inlet connectors being orientable by rotation before cementing to the outside of the hemi-spherical portion 11.

When the bowl 10 is supplied to the user, three of the inlets 14 will normally be provided with removable flexible polypropylene covers 1 5, since it is unlikely that this system will be employed unless there is intended to be at least one fluid inflow to the bowl, and one inlet 1 4 is therefore uncovered. Each cover 1 5 is identical and is shown in detail in Figures 2 and 3, whilst Figure 1 shows one cover 1 5 in position.

Cover 15 has a circular perimeter slightly larger than the inlet 14 so that it just overlaps inlet 14 on the inside of the hemi-spherical portion 11. Cover 1 5 is moulded as a thin-walled plastics section, being curved to the same radius as the hemi spherical portion 11, thereby providing a generally non-undulating surface within the bowl 10. Its wall thickness is less than that of the hemi spherical portion 11.

Integrally moulded with the cover 1 5 on its convex side are two engaging lugs 1 6 and 1 7 respectively, which are positioned so that they engage the perimeter of the inlet 14 and hold cover 15 in position. The first lug 1 6 has the shape of half an arrow head as seen in the view of Figure 3, whilst the second lug 1 7 is shaped so that its sides diverge as they extend away from cover 1 5 as seen in the view of Figure 3. The lugs 16 and 1 7 are positioned diametrically opposite one another on the cover 15, and are dimensioned so that by pushing on the central region of cover 1 5 from its convex side, the lugs 16, 17 will disengage from the perimeter of inlet 14 so that the cover 1 5 can be removed.

Two locating lugs 1 8 and 19 are also integrally moulded on the same side of cover 1 5 as the engaging lugs 1 6 and 17, but each spaced by ninety degrees from engaging lugs 1 6 and 1 7.

Locating lugs 1 8 and 19 are of rectangular shape and serve in locating the cover centrally with respect to the inlet 14 when installing the cover 15.

In use, the bowl 10 with three of its inlets 14 covered is taken to the site where it is to be installed. If two or more inflows are to be connected to the bowl, a cover 1 5 appropriate to the inflow direction is removed as described above, and respective inlet connectors are solvent cemented around each inlet, being oriented as required. The invention thereby avoids the need for on-site cutting of inlet holes in the access bowl by special tools, thereby ensuring more rapid instaliation. Furthermore, a bowl which has already been positioned may be readily adapted to accept an additional inflow simply by the removai of a further cover 1 5.

The inlets 14 shown in Figure 1 are shown at a common height above the outlet 12. Whilst this may well be suitable for a particular design of bowl, the heights may well differ one from another, but the centres of the inlets will generally fall within a belt of the hemi-spherical portion 11.

Claims (13)

1. A drainage access bowl having a curved interior surface, a basal outlet, and a plurality of inlets spaced upwardly in the side of the bowl from the basal outlet, one or more of said inlets being provided with a removable cover.

2. A drainage access bowl as claimed in Claim 1 wherein the interior surface of the bowl forms part of a sphere.

3. A drainage access bowl as claimed in Claim 1 or Claim 2 wherein the inlets are symmetrically located about the bowl.

4. A drainage access bowl as claimed in any preceding claim wherein all but one of the inlets are provided with a removable cover.

5. A drainage access bowl as claimed in any preceding claim wherein the removable cover is shaped so that its inner surface conforms substantially to the inner surface of the bowl.

6. A drainage access bowl as claimed in any preceding claim wherein the cover is made removable from the inside of the bowl by the application of pressure to the central region of the cover.

7. A drainage access bowl as claimed in any preceding claim wherein the cover is made of flexible or elastomeric plastics material.

8. A drainage access bowl as claimed in any preceding claim wherein the cover engages the perimeter of the inlet by means of integrally formed lugs.

9. A drainage access bowl as claimed in Claim 8 wherein the cover is made removable by pressing the central region of the flexible cover to disengage the lugs from the perimeter of the inlet.

10. A drainage access bowl as claimed in Claim 8 or Claim 9 wherein at least one of the engaging lugs is shaped as half of an arrow head, namely split down the axis of symmetry of an arrow head when seen in cross-section extending from the cover.

11. A drainage access bowl as claimed in Claim 8, 9 or 10 wherein the engaging lugs are formed diametrically opposite one another.

12. A drainage access bowl as claimed in any preceding claim wherein integrally moulded locating lugs are provided on the inlet side of the cover.

13. A drainage access bowl as hereinbefore described with reference to and as shown in the accompanying drawings.