GB2057595A - Seal Assembly - Google Patents

Abstract

To prevent fluid, such as gas leaking from a service duct, from travelling through a wall or the like penetrated by the duct or a cable, and yet to allow for relative movement of duct or cable and wall, a seal element (2) which is a one-piece moulding surrounds the duct or cable. The element has an inner sleeve (2a) and outer sleeve (2b) joined by a flexible, elastic web (8) which forms a barrier against fluid flow in the axial direction in the gap between the sleeves. The sleeves may make direct with the duct and wall respectively, and be respectively internally and externally resiliently ribbed (10). Preferably two said elements (2) will be placed axially back to back on a single duct with their webs (8) adjacent. End caps fitted over the open ends of the sleeves to seal off the gap between them do not rigidify the elements. <IMAGE>

Description

SPECIFICATION Service Entry Seal This invention relates to the formation of seals around service carrier ducts (such as gas or water pipes, electricity or telephone cables) where they penetrate walls, etc., of buildings, and to seal elements for that purpose.

It is obviously desirable in general to prevent fluid flow occurring outside a service carrier duct through the aperture which must be formed in a wall to allow the service carrier duct to penetrate the wall. It is vitally important to prevent that flow when the duct is carrying gas and there may have been leakage of gas at some point along the duct: if such gas travels along the outside of the duct (where there tends to be a path of least resistance) and is allowed to collect in a building there will be a risk of asphyxiation or explosion.

Such apertures have in the past been simply plugged by polyurethane foams or by mastics, but these plugs are not flexible and consequently are liable to crack if any relative movement of duct and aperture occurs e.g. due to earth movement or settlement. A further disadvantage of such plugs is that they are applied on site and it is difficult to maintain strict quality control.

Preformed seal element of sleeve-like conformation have previously been proposed but always, so far as we are aware, for preventing leakage from out of a duct (typically as a gland or packing for preventing leakage from a joint between two parts of a duct) rather than for preventing movement of fluid along a duct and outside it.

Such prior art is seen in U.K. Patent Specifications 1032 and 1229216. In U.K.

311032 a packing between inner and outer parts of a duct is in the form of a double cylindrical sleeve joined at one end by a wall. To ensure a seal to prevent leakage of fluid from between the parts a clamp ring is inserted from the open end to wedge the sleeves apart, thereby also centring and fixing the inner and outer parts. In U.K.

1229216 a bell of a duct part such as a syphon is fitted with an end flange with an inner, terminally restricted flexible sleeve and an outer positioning skirt to fit within the bell. A spigot of the duct is forced into the inner sleeve which is terminally expanded thereby, to form a seal preventing escape of fluid from the duct.

The prior art also includes many examples of ends of two duct parts being fitted together within a third by the use of elastomeric elements disposed respectively around the ends in mirrorimage relationship and being forced into (or being already positioned within) the third element. See e.g. U.K. PS 725557, 1118847, 1118895. Once more the object is to prevent leakage from out of the duct.

The invention has as its object a preformed seal element which is not for preventing leakage from a duct but for preventing fluid flow along the line of the duct and outside it. It is therefore an element which surrounds the duct and which may be in direct contact with it but which so to offer a barrier to axial flow between the duct and what surrounds it. This will normally be an aperture in a wall of a building or the like where the service carrier duct enters the building or a sector of the building.

It is to be robust in its construction; it will contact the wall of the building (or a conduit sleeve built into that wall) and the duct (or a sleeve surrounding the duct and solid with it) over a generally equal extension and equally robustly.

This is done by having comparatively heavy sleeves for both contacts and joining them by a web to form a barrier to axial fluid flow in the annular gap between the sleeves.

To solve the problem of the cracking or distortion imposed on the prior art mastic seals by earth movement or subsidence, the web is made to be flexible at least in the radial direction, and very suitably this is made possible by the seal being a one-piece integral moulding of a plastics material. Moulding is made particularly easy by providing the web at one end of the sleeves.

It should be a toughly resilient material so as to be fitted on site by being slid along the duct into sealing engagement between it and the aperture and then to be left unsupported to maintain its seal with a very long life expectancy.

This robustness with radial resilience is also assisted by provision of axially-extending webs or walls joining the two sleeves along the whole of their length.

The seal thus formed around a duct can be made particularly effective by the use of two such sealing elements in mirror-image relationship on the duct and having a total extension substantially the same as the length of the aperture. When the web is at one end of the sleeves, the webs of such elements should be adjacent, even abutting.

Particular embodiments of the present invention will now be described by way of example with reference to the accompanying drawings in which~ Figure 1 is a side elevation of a seal unit embodying the invention; Figure 2 is a view of the seal unit of Figure 1 looking in the direction of arrow A; Figure 3 is a plan view of a cap to be fitted over the end of the seal unit shown in Figure 2; Figure 4 is a cross-section of the cap shown in Figure 3, on the line IV to IV of Figure 3; Figure 5 is a cross-sectional view of the seal of Figures 1 to 4 in use on a carrier service in a cavity wall; and Figure 6 is a side elevation of a second embodiment.

Referring to Figures 1 and 2 there is shown a plastics seal element 2 substantially cylindrical in shape and consisting of an inner sleeve 2a and an outer sleeve 2b joined by four walls 3 extending axially (i.e. lying in axial planes) and an end wall 8 at one end. The other end 6 is open. The sleeve 2a provides a central bore 4, which is coaxial with the longitudinal axis of the element 2, for receiving a carrier service such as a gas or water pipe or a telephone or electricity cable or duct.

The bore 4 extends along the whole length of the seal element 2 and is open at both ends.

Circumferential rectangular section ribs 10 are provided on the external surface of the outer sleeve 2b and on the internal surface of the inner sleeve 2a. The ribs 10 are equispaced along the whole length of the seal element 2 and each of the ribs 10 is of the same width (i.e. the dimension parallel to the longitudinal axis of the seal element 2) as grooves 12 which occur between the ribs 10.

As mentioned, the internal surface of the sleeve 2a also has circumferential ribs along its length, as can be more easily seen in Figure 1.

The broken line 14 indicates the depth of grooves formed by the internal ribs.

When the seal element is in use, the end 6 is covered by a flanged annular cap 18 shown in Figures 3 and 4. The cap 18 comprises an annulus 20 and a flange 22 which is formed integrally with the annulus 20. The inner circumference of the flange 22 is approximately equal to the outer circumference of the ribs 10 on the seal element 2; the cap 18 therefore engages snugly with the seal element 2 and provides a gas-tight closure. An adhesive is used to retain the cap 18 on the seal element 2 and to make the gas-tight closure.

An aperture 24 is provided in the cap 18 to accommodate the carrier service. The aperture 24 is concentric with the bore 4 of the seal element 2 and is approximately 1 mm greater in diameter than the bore 4.

A completion service entry embodying the invention will now be described with particular reference to Figure 5. Two seal elements 2 are pushed together on a carrier service 26 in mirrorimage formation so that their walls 8 are adjacent or abut one another. The two open ends 6 are each covered by a cap 18. The whole assembly is located in an aperture 28 bored in a cavity wall consisting of two skins 30 and 32 with a cavity 24 between them and is of substantially the same length as the length of the bore 28.

A service entry embodying the invention can be either below or above ground level. The circumferential ribs 10 on the external surfaces of the seal elements 2 and in the carrier service receiving bores 4 ensure a gas-tight engagement of the service entry seal with the surrounding masonry and the carrier service respectively, even if the sizes of the service and the aperture in the wall are not exact. The flexibility and resilience of the ribs 10 and of the web 8 allow for movement, e.g. of the wall, to take place, without losing the seal. The seal element may alternatively be housed in a protective pipe or sleeve fixed in the wall, which engages with the external circumferential ribs.

As well as preventing the entry of leaked gas into a building, use of the present service entry seal prevents moisture from seeping in through a carrier service entry, and prevents heat escaping.

Further, access for rodents is effectively blocked.

Figure 6 shows how two variations may be applied to the sleeve; both are seen in one embodiment here but they are independently applicable. Firstly to give desired non-uniform properties of compressibility, the wall thickness of the outer sleeve 2b' and inner sleeve 2a' may be varied by a slight taper angle (1 is shown) on the inner peripheral surface 5 of the outer sleeve and on the outer peripheral surface 7 of the inner sleeve. Alternatively or additionally squaresection ribs such as 10 may be replaced by other endless ribs such as the obtuse triangular-section shape seen at 11 in this Figure. The end view of this embodiment is generally as seen in Figure 2, differing only in that the taper will be visible.

Claims (12)

Claims

1. A seal element for surrounding a carrier duct where the latter penetrates an aperture, the element including inner and outer sleeves and a flexible continuous web joining them whereby when the inner and outer sleeves are respectively seatingly related to the duct and aperture the web forms a barrier to fluid flow along the duct between the sleeves.

2. An element according to Claim 1, wherein the web is at one axial end of the sleeves.

3. An element according to Claim 1 or Claim 2, wherein there are additionally longitudinal flexible elastic webs between the sleeves.

4. An element according to Claim 1, 2 or 3 which is an integral one-piece whole.

5. An element according to Claim 1 substantially herein described and with reference to and as illustrated in the accompanying drawing.

6. A seal assembly including a carrier service duct, an aperture in a wall penetrated by and surrounding the duct, and sealing means surrounding the duct between the wall and the duct for preventing the flow of fluid along the duct outside the duct, the sealing means being a seal element having an inner sleeve and an outer sleeve spaced apart from the inner sleeve, the sleeves being joined by a resilient flexible web thereby the duct and wall may move relatively without rupturing the web.

7. A sealing assembly according to Claim 6, wherein the inner sleeve of the seal element is in direct contact with the duct.

8. A sealing assembly according to Claim 6 or Claim 7, wherein either or both of the innermost surface of the inner sleeve and the outermost surface of the outer sleeve are provided with resilient endless ribs.

9. A sealing assembly according to any one of Claims 6 to 8, wherein there are two said seal elements surrounding the duct and axially adjacent to each other, the elements being in mirror-image formation.

10. A sealing assembly according to Claim 9, wherein the web of each seal element is at one axial end of the respective element and the webs of the two elements are arranged axially adjacent to each other.

11. A sealing assembly according to any one of Claims 6 to 10, wherein the or each seal is further provided with an end cap fitting over an open end of the sleeves to close off the gap between them.

12. A sealing assembly substantially as herein described with reference to and as illustrated in the accompanying drawings.