GB2031480A - Manholes - Google Patents

Abstract

A manhole drainage-access chamber is formed of plastics material with a bottom integral with a circular or other curved side wall 3 which diverges upwardly and has adjacent the bottom a plurality of substantially circular moulded or cut side openings 4A...F each for sealing to a pipe or a stopper or an adaptor for a pipe. The bottom is preferably formed with a primary flow channel 5 between two opposite openings, and secondary channels 5C...F from the further openings at a higher level. Grommets may be used in the side openings for sealing round pipes, stoppers or adaptors. A lower portion of the side wall including all the openings may, Fig. 6 (not shown), have a reduced cross-section to facilitate nesting of one chamber inside another with grommets in place, the transition between the two cross-sections merging into benchings between the primary channel and the secondary channels. <IMAGE>

Description

SPECIFICATION Manholes This invention relates to manholes (which expression also includes inspection chambers) for use in drainage or sewerage systems, such chambers being described in British Patent No. 1 192 650, its Patent of Addition No.

1272039, and British Patent No. 1 447 227, and has for its object the provision of a standard manhole access chamber not only readily adaptable to a wide variety of drainage pipe layouts but also facilitating rodding from the top of the manhole of pipes connected to the chamber and generally clearing dirt and debris from the inside of the chamber.

According to the present invention, a manhole access chamber is formed of plastics material with a bottom integral with a side wall, the side wall having in horizontal section a continuously curving profile from adjacent the bottom and diverging upwardly, and the side wall having immediately adjacent the bottom a plurality of substantially circular side openings each for sealing to a pipe or a stopper or an adaptor for a pipe.

The continuous curving of the side wall ensures the maximum possible internal dimensions at the bottom relative to the internal dimensions at the top of the manhole and this facilitates rodding of pipes connected to the chamber as well as generally clearing dirt and debris from the inside of the chamber.

However, the integral bottom is preferably formed with a primary channel extending between two diametrically opposed side openings (one of which is intended to have sealed therein an outlet pipe) and with a secondary channel leading to the primary channel from the or each further side opening between benchings, to direct the flow and keep the inside of the chamber clear. The or each secondary channel is preferably disposed above the primary channel, so that the flow in the primary channel will not back into the or a secondary channel, and the or each secondary channel preferably curves towards one of the side openings at an end of the primary channel (i.e., the side opening that is intended to have sealed therein an outlet pipe).

The circular side openings may be fitted with rubber grommets (which are preferably of the type described and claimed in British Patent No. 1 41 7 778 of Hepworth Plastics Limited) each for sealing round a pipe or a stopper or an adaptor for a pipe. All the circular side openings may also be fitted with stoppers, any one or more of which are removed on site ready for the insertion of a pipe or pipes (or adaptors) into sealing engagement with the rubber grommets.

An adaptor for a pipe may alternatively be provided with a circumferential flange bonded, cemented or welded to the outside of the chamber around a side opening; or the adaptor may also be provided with a barb running continuously or intermittently round the circumference of the adaptor to snap into a side opening and compress a sealing ring between the flange and the outside of the chamber around the side opening.Again an adaptor may be provided with an external screwthread for screwing into a side opening provided with a mating screwthread, to compress a sealing ring between a circumferential flange on the adaptor and the outside of the chamber around the side opening; or the side opening may be provided with two or more (e.g., four) radial projections for engagement in bayonet slots in an adaptor having a circumferential flange between which and the outside of the chamber around the side opening a sealing ring is compressed. Variable compression around the sealing ring may accommodate the slight curve of the chamber across the side opening.

While the omission of stoppers (or adaptors) facilitates the close nesting of one manhole access chamber in accordance with the invention inside another for storage and transport, because of the lack of or minimising of projections radially beyond the continuously curved side wall, a lower portion of the side wall including all the circular side openings may have lesser internal and external cross-sectional areas than the remainder of the side wall, so that with stoppers sealed in all the circular side openings one chamber in accordance with the invention can still be nested inside another; thus, a transition between the lower portion of the side wall and the remainder may merge into swept benchings between the primary channel and the or each secondary channel.

The lower part of the end of the or each channel adjacent an opening is preferably enlarged to afford location for an inserted pipe end (or adaptor), and a further enlargement is preferably provided for accommodation of a rubber grommet.

The "plastics material" may comprise injection moulding or blow or rotational moulding materials, and glass-fibre or other reinforced resins capable of withstanding attack by the usual drainage and sewerage effluents, and the chamber is preferably capable of use as it stands or when surrounded in situ by lowgrade concrete or other suitable filler for which the plastics material determines the shape and provides the internal surface. The circular side openings may be formed by moulding, but-conveniently-the use of complex moulding tools (with withdrawable cores for forming the openings) can be avoided by jig-cutting the openings after moulding the chamber with a substantially uniform and uninterrupted side wall and integral bottom.

It will be appreciated that a circular internal and external horizontal cross-section may be provided for the side wall, the upper end of which may be fitted with a circular frame for a circular manhole cover, but other continuously curved horizontal cross-sections could be employed to increase the facility with which pipes connected to the chamber can be rodded from the top of the manhole, or to enable more than two side openings to be provided to each side of a primary channel.

An extension piece, preferably with socket engagement between its lower end and the upper end of the chamber jointed with a suitable cement, may be used to provide a transition from a non-circular chamber side wall to a circular manhole cover frame, or merely to increase the height to a manhole cover on a circular chamber.

A number of embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a chamber in accordance with the invention, with part of the side wall broken away to show the internal formation of the integral bottom; Figure 2 is an enlarged fragmentary section of the chamber of Fig. 1; Figure 3 is a further enlarged fragmentary section showing a grommet with nozzle fitted in a side opening of the chamber; Figures 4 and 5 correspond to Fig. 3 but show respectively a pipe end and a stopper sealed into the side opening of the chamber by the grommet; Figure 6 corresponds to Fig. 1 but shows another form of chamber in accordance with the present invention; Figure 7 is an enlarged fragmentary section of two chambers as in Fig. 6 shown nested one inside the other;; Figure 8 is a further enlarged fragmentary section showing an adaptor sealed into a side opening of a chamber by a grommet; Figures 9 to ii correspond to Fig. 8 but show other ways of securing and sealing adaptors into side openings of chambers in accordance with the invention; Figure 12 is a fragmentary elevation of a modified form of side opening for a chamber in accordance with the invention Figure 13 is a fragmentary section from the line 13-13 of Fig. 12; Figure 14 is a corresponding section of an adaptor for securing and sealing in the side opening of Figs. 1 2 and 13; Figure 15is a fragmentary view in the direction of the arrow X in Fig. 14; Figure 16 is a perspective view of yet another form of chamber in accordance with the invention; and Figure 17 is an enlarged horizontal section across the bottom of the chamber of Fig. 1 6 with the stoppers omitted from the side openings.

In Figs. 1 and 2 a manhole access chamber 1 is formed of plastics material with a bottom 2 integral with a side wall 3, the side wall having a circular horizontal section diverging upwardly from adjacent the bottom, and the side wall has immediately adjacent the bottom a plurality of circuit side openings 4A, 4B, 4C, 4D, 4E, and 4F each for sealing to a pipe or a stopper or an adaptor for a pipe as will be described presently.

The integral bottom 2 is formed with a primary channel 5 extending between the side openings 4A, 4B, the latter of which is intended to have sealed therein an outlet pipe, and with secondary channels 5C, 5D, 5E, 5F leading to the primary channel from the respective further side openings 4C, 4D, 4E, 4F, between benchings 6, to direct the flow and keep the inside of the chamber clear of dirt and debris. Each secondary channel is disposed above the primary channel, so that the flow in the primary channel will not back into any secondary channel, and the secondary channels curve towards the side opening 4B which is intended to have sealed therein an outlet pipe.

The upper end of the chamber is formed with a socket 7 for location of a manhole cover, or a frame for a manhole cover (e.g., as shown in Fig. 16) or for an extension piece (not shown) with a corresponding spigot at its lower end and a corresponding socket at its upper end.

Each of the side openings 4A to 4F may be fitted with a rubber grommet 8 as shown in Fig. 3 and of the type described and claimed in British Patent No. 1 778. Fig. 4 shows such a grommet effecting sealing of a pipe end 9 inserted into an opening, while Fig. 5 shows such a grommet effecting sealing of a stopper 10 in an opening. The end 11 of each channel 5 and 5C to 5F adjacent an opening is enlarged to afford location for an inserted pipe end, and a further enlargement 12 is provided for accommodating the grommets.

While the omission of stoppers 10 facilitates the close nesting of one chamber 1 inside another (as indicated in broken lines in Fig. 2) for storage and transport, all the circular side openings may be fitted with stoppers (any one or more of which are removed on site) with the modified form of chamber shown in Figs. 6 and 7, in which a lower portion 3X of the side wall including all the side openings has lesser internal and external diameters than the remainder of the side wall 3, so that one chamber can still be nested inside another, as shown in Fig. 7. The transition 1 3 between the lower portion 3X of the side wall and the remainder 3 merges into the swept benchings 6.

Fig. 8 shows an adaptor 14 for a pipe (not shown), the adaptor having a spigot 15 for sealing in an opening 4 in a chamber wall 3 by means of a grommet 8 and a socket 16 with a sealing ring 1 7 held in place by a locking ring 18.

In Fig. 9 an adaptor 19 (with a sealing ring 1 7 and locking ring 18) has a circumferential flange 20 bonded, cemented or welded to the outside of the chamber around a side opening 4, while in Fig. 10 an adaptor 21 having a circumferential flange 22 is also provided with a barb 23 running continuously or intermittently round the circumference of the adaptor to snap into a side opening 4 and compress a sealing ring 24 between the flange 22 and the outside of the chamber around the side opening. Variable compression round the sealing ring 24 accommodates the slight curve of the chamber wall 3 across the side opening.

In Fig. 11 an adaptor 25 is provided with an external screwthread 26 for screwing into a side opening provided with a mating screwthread 27, to compress a sealing ring 28 between a circumferential flange 29 on the adaptor and the outside of the chamber wall 3 around the side opening; while in Figs.

1 2 to 15 a side opening 4 is provided with four radial projections 30 for engagement in bayonet slots 31 in an adaptor 32 having a circumferential flange 33 between which and the outside of the chamber wall 3 a sealing ring 34 is compressed.

In Figs. 1 6 and 1 7 a manhole access chamber 35 has a bottom 36 integral with a reduced lower portion 37X of a side wall 37 having a non-circular continuously curving horizontal section diverging upwardly to a socket-and-spigot joint with an extension piece 38, which terminates in a circular portion 39 to which is fitted a frame 40 for a cover 41.

Because of the elongation of the horizontal section, the chamber can accommodate two further side openings 4G and 4H (with secondary channels 5G and 5H) additional to the side openings 4A to 4F (with primary channel 5 and secondary channels 5C to 5F), all the openings being shown open in Fig. 1 7 and closed by stoppers 10 where visible in Fig.

Claims (18)

1. A manhole access chamber formed of plastics material with a bottom integral with a side wall, the side wall having in horizontal section a continuously curving profile from adjacent the bottom and diverging upwardly and the side wall having immediately adjacent the bottom a plurality of substantially circular side openings each for sealing to a pipe or a stopper or an adaptor for a pipe.

2. A chamber as in Claim 1, wherein the integral bottom is formed with a primary channel extending between two diametrically opposed side openings and with a secondary channel leading to the primary channel from the or each further side opening between benchings, to direct the flow and keep the inside of the chamber clear.

3. A chamber as in Claim 2, wherein the or each secondary channel is disposed above the primary channel, so that the flow in the primary channel will not back into the or a secondary channel, and the or each secondary channel preferable curves towards one of the side openings at an end of the primary channel.

4. A chamber as in any one of the preceding Claims, wherein the circular side openings are fitted with rubber grommets each for sealing round a pipe or a stopper or an adaptor for a pipe.

5. A chamber as in Claim 4, wherein all the circular side openings are fitted with stoppers.

6. A chamber as in any one of Claims 1 to 3, wherein an adaptor for a pipe is provided with a circumferential flange bonded, cemented or welded to the outside of the chamber around a side opening.

7. A chamber as in any one of Claims 1 to 3, wherein an adaptor for a pipe is provided with a circumferential flange and also a barb running continuously or intermittently round the circumference of the adaptor to snap into a side opening and compress a sealing ring between the flange and the outside of the chamber around the side opening.

8. A chamber as in any one of Claims 1 to 3, wherein an adaptor for a pipe is provided with an external screwthread for screwing into a side opening provided with a mating screwthread to compress a sealing ring between a circumferential flange on the adaptor and the outside of the chamber around the side opening.

9. A chamber as in any one of Claims 1 to 3, wherein the or each side opening is provided with two or more radial projections for engagement in bayonet slots in an adaptor having a circumferential flange between which and the outside of the chamber around the side opening a sealing ring is compressed.

10. A chamber as in any one of the preceding Claims, wherein a lower portion of the side wall including all the circular side openings has lesser internal and external cross-sectional areas than the remainder of the side wall.

11. A chamber as in Claim 10 in combination with Claim 2 or Claim 3, wherein a transition between the lower portion of the side wall and the remainder merges into swept benchings between the primary channel and the or each secondary channel.

1 2. A chamber as in Claim 2 or Claim 3, wherein the lower part of the end of the or each channel adjacent an opening is enlarged to afford location for an inserted pipe end.

1 3. A chamber as in Claim 12, wherein a further enlargement is provided for accommodation of a rubber grommet.

1 4. A chamber as in any one of the preceding Claims, wherein the side wall has a circular internal and external horizontal crosssection.

15. A chamber as in Claim 14, wherein the upper end is fitted with a circular frame for a circular manhole cover.

16. A chamber as in Claim 14, wherein an extension piece is used to increase the height to a manhole cover on a circular chamber.

1 7. A manhole access chamber substantially as hereinbefore described with reference to Figs. 1 and 2 or Figs. 6 and 7 or Figs. 16 and 1 7 of the accompanying drawings.

18. A manhole as in Claim 17 modified substantially as hereinbefore described with reference to any of Figs. 3 to 5, and 8 to 15.