GB2426299A

GB2426299A - Slideable annular seal for pipes

Info

Publication number: GB2426299A
Application number: GB0509983A
Authority: GB
Inventors: Laurence Evans
Original assignee: SPARTAL Ltd
Current assignee: SPARTAL Ltd
Priority date: 2005-05-16
Filing date: 2005-05-16
Publication date: 2006-11-22
Also published as: GB0509983D0

Abstract

A slideable seal 101 maybe used to join flue pipes. The slideable seal 101 has seal ridges 110, 130 for respectively sealing against the exterior of an inner pipe 110 and an outer pipe 111. The inner pipe 110 may be telescopically received within the outer pipe 111, thus allowing the length of the flue pipe to be adjusted to suit an installation. Preferably, a shoulder 200 is provided as an end stop for the outer pipe 111 and preferably also to align the inner pipe 110 concentrically with the outer pipe 111. Preferably, locating projections 210 are provided for projecting into corresponding holes 211 in the outer pipe 111, thereby securing the slideable seal 101 to the outer pipe. Preferably, an o-ring 220 is placed around the locating projections 210. The o-ring 220 urges the locating projections 210 into the holes 211 in the outer pipe. The slideable seal 101 may be injection moulded from EPDM rubber.

Description

SLIDEABLE SEAL

Background

The present invention is concerned with a slideable seal, particularly but not exclusively, a slideable seal for flue pipes for boilers.

Condensing boilers are becoming popular for domestic central heating systems. Typically, a concentric flue system is used comprising two coaxial flue pipes which terminate at the exterior of a domestic residence. The annular region between the outer pipe and inner pipe conveys air to the condensing boiler; and the inner pipe discharges the flue gas at low pressure (i.e. slightly above the ambient atmospheric pressure) to the atmosphere.

Typically, a telescopic concentric flue system is used to allow an installer of a condensing boiler to readily connect a condensing boiler to a termination point mounted on the exterior of a domestic residence. The inner pipe flue pipe is made of a pipe that telescopes within a separate inner pipe of slightly larger diameter. The outer flue pipe may also be made of a pipe that telescopes within a separate outer pipe of slightly larger diameter. The use of a telescopic system allows the installer to readily adapt the flue to the correct length, eliminating the need to cut to length. Usually, once the correct flue length has been achieved, the inner and outer pipes will not be moved relative to each other until the condensing boiler needs replacing.

When a telescopic concentric flue system is used there are actually a total of four pipes: the outer flue pipe is typically made up of an outer pipe and an inner pipe; the inner flue pipe is made up of an outer pipe and an inner pipe. Typical pipe diameters for concentric flue systems are: (i) outer pipe 125mm, inner pipe 80mm, or (ii) outer pipe 100mm, inner pipe 60mm.

Condensing boilers generate an acidic, liquid, condensate which can run down the inside of the inner pipe back to the boiler where it is run to waste. During operating conditions, several litres of condensate may be produced each hour by a domestic boiler. A seal is therefore required between the telescopic sections of the inner pipe to prevent the acidic liquid escaping into the outer pipe or elsewhere. Typically, the outer (air) pipe is made from either metal or plastic while the inner/flue gas pipe is made from plastic in order to withstand the acid. The flue assembly (inner and outer pipe) is mounted horizontally, with a slight downwards inclination (approximately 3 ) down towards the condensing boiler.

A known slideable seal for a telescopic inner flue pipe has an annular rubber seal retained within a circular groove/recess in the inner wall of the outer pipe (the telescopic inner flue pipe itself comprises an irmer pipe and an outer pipe). The inner pipe telescopes within the outer pipe and the outer wall of the inner pipe forms a seal against the rubber seal. A disadvantage of the known slideable seal is that it requires a groove for the rubber seal to be formed in the outer pipe. The process of forming the groove is relatively expensive and furthermore cannot readily be performed on-site during installation of the flue. Thus a section of outer pipe with a circular groove is always required.

Statement of Invention

According to the present invention, there is provided a slideable seal for sealing two pipes, the slideable seal comprising: an annular body; a first seal portion provided at the interior of the annular body towards one end of the annular body; and a second seal portion provided at the interior of the annular body towards the other end of the annular body.

Description of Figures

Fig. 1 shows an exploded view of an inner pipe, a slideable seal according to a first embodiment, and an outer pipe.

Fig. 2 shows a cross-sectional view of Fig. 1, and also shows a crosssectional view of an 0-ring fitted to the slideable seal.

Fig. 3 shows a cross-sectional view of a second embodiment of a slideable seal, but does not show any pipes.

First embodiment Fig. 1 shows an exploded view of a seal assembly 100. A slideable seal 101 allows a continuous seal to be formed between an inner pipe 110 and an outer pipe 111. In this embodiment, the inner pipe 110 has an outside diameter of 60mm and the outer pipe Ill has an inside diameter of6lmm (and an outside diameter of 65mm), thus the pipes 110, are suitable for use as the inner pipe of a condensing flue system.

The slideable seal 101 is formed in this embodiment from ethylene propylene diene monomer (EPDM) rubber. The hardness of the EPDM rubber may be selected to allow easy assembly of the seal assembly 100 while giving sufficient durability.

Seal ridges/lips 130 are provided at one end of the slideable seal 101 for forming a seal against the exterior of the inner pipe 110. In this embodiment the seal ridges 130 are integrally formed from EPDM rubber with the remainder of the slideable seal 101. The seal ridges 130 are annular, with a generally triangular cross-section, and project inwardly from the slideable seal 101. Each of the seal ridges 130 forms a circular seal around the periphery of the inner pipe 110.

As shown by Fig. 2, seal ridges 230 are provided at the other end of the slideable seal 101 for forming a seal against the exterior of the outer pipe ill. The seal ridges 230 are similar to the seal ridges 130. Thus when the inner pipe 110 and the outer pipe lii are pushed into the respective ends of the slideable seal 1 01, a seal is formed between the inner pipe 110 and the outer pipe 111. The inner pipe 110 can be slid relative to the outer pipe Ill (and also relative to the slideable seal 101 which is secured to the outer pipe Ill) and thus excess length of the inner pipe 110 can be accommodated within the outer pipe 111 as shown.

In this embodiment an annular shoulder 200 is provided in the interior of the slideable seal 101. The shoulder 200 functions as an end stop to prevent the outer pipe I ii from being pushed too far into the slideable seal 101.

To prevent the outer pipe Ill from being disengaged with the slideable seal 101, in this embodiment four locating projections 210 are provided at the interior of the slideable seal 101. The locating projections 210 are dimensional in accordance with the outer pipe 111.

Here, the outer pipe 111 has an outside diameter of 65mm and so the locating projections 210 project radially inwards from the interior of the slideable seal 101 by 2mm (the wall thickness of the outer pipe 111 is 2mm). The locating projections 210 are integrally formed from the EPDM rubber.

Four holes 211 are provided, in this embodiment, in the outer pipe 111 for mating with the locating projections 210. The holes 211 are radially arranged with a 90 separation around the circumference of one end of the outer pipe 111. During installation of a flue, an installer may drill the holes 211 by using, for example, a hand-held electric drill.

Preferably, the inner ends of the locating projections 210 meet on a circle with the same diameter as the inner diameter of the shoulder 200; thus when the inner pipe 110 is inserted into the slideable seal 101, the shoulder 200 and the locating projections 210 will bear against the exterior of the inner pipe 110. In this embodiment the locating projections 210 are arranged to project radially inwards from the body of the slideable seal 101 further than the seal ridges 230; thus when the outer pipe 111 is inserted, the exterior of the outer pipe will press firmly against the seal ridges 230 (thereby ensuring a good seal) but will not be prevented by the seal ridges 230 from being pushed into engagement with the locating projections 210.

To further retain the outer pipe 111 within the slideable seal 101, an 0ring 220 is preferably stretched and mounted over the slideable seal 101 and is retained in a groove 121 on the exterior of the slideable seal 101. The groove 121 is axially aligned with the locating projections 210 and thus tension in the 0-ring 220 urges the locating projections 210 radially inwards. The groove 121 is preferably formed during moulding of the slideable seal 101.

When the outer pipe 111 is initially inserted into the slideable seal 101, the slideable seal 101 deforms slightly, thus allowing the locating projections 210 to slide over the exterior of the outer pipe 111. When the locating projections 210 reach the holes 211 during insertion of the outer pipe 111, the resilience of the slideable seal 101 causes the locating projections 210 to be inserted into the holes 211, thereby captively retaining the outer pipe Ill within the slideable seal 101. Of course, if the locating projections 210 are not rotationally aligned with the four holes 211, relative rotation between the slideable seal 101 and the outer pipe 111 will be required to insert the locating projections 210 into the holes 211.

The inner pipe 110 can then be inserted into the slideable seal 101 and into the outer pipe 111. Preferably, the shoulder 200 has an interior diameter arranged so that the shoulder bears against the exterior of inner pipe 110 and thus aligns the inner pipe 110 concentrically with the outer pipe 111. In this embodiment the seal ridges 130 are arranged to project radially inwards from the body of the slideable seal 101 further than the shoulder 200; thus when the inner pipe 110 is inserted, the exterior of the inner pipe 110 will press firmly against the seal ridges 130 (thereby ensuring a good seal) but will press relatively gently against the shoulder 200 (thereby ensuring that the inner pipe 110 can be slid relative to the slideable seal 101).

To aid the insertion of the inner pipe 110 into the slideable seal 101 a small amount of liquid silicone lubricant may be used to make assembly easier and the action of the slideable seal 101 smoother when inner pipe 110 is inserted or withdrawn.

Second embodiment Fig. 3 shows a cross-sectional view of a second embodiment 301 of a slideable seal. Fig. 3 does not show the inner pipe 110 or the outer pipe 111. The slideable seal 301 differs from the slideable seal 101 in that an 0-ring 320 is moulded integrally with the slideable seal 301. This has the advantages of reducing the number of parts (as a separate 0-ring is not required) and of making installation easier (as the installer cannot inadvertently lose the o- ring).

As before, the slideable seal 301 has seal ridges/lips 130 and 230 at each end of the body of the slideable seal 301. Locating projections 210 are spaced at 90 about the interior of the slideable seal 301.

At one end of the slideable seal 301 (in this embodiment the end with the seal ridges), the slideable seal 301 is extended by an annular web 310 which connects the slideable seal 301 to the 0-ring 320. In this embodiment the wall thickness of the annular web 310 is thin compared to the wall thickness of the body of the slideable seal 301 and thus the web 310 and 0-ring 320 can readily be stretched and folded back over the body of the slideable seal 301.

Fig. 4 shows the slideable seal 301 with the annular web 310 and 0-ring 320 folded back over the body of the slideable seal 301, so that the 0ring 320 is held within the groove 121.

In an alternative embodiment of the sl ideable seal 301, the annular web 310 may be made sufficiently thin to allow an installer to separate the 0ring 320 from the slideable seal 301 (some installers may prefer to separate the 0-ring 320 from the slideable seal 301 rather than leaving the 0-ring 320 connected to the slideable seal 301). Alternatively, the web may not be annular but may instead simply connect the 0-ring 320 to the slideable seal 301.

Further embodiments The slideable seals 101, 301 both had an annular cross-section in a plane perpendicular to the longitudinal axis of the pipes 110, 111. In alternative embodiments, the slideable seals may have, for example, an oval cross-section to allow them to be used with oval pipes (instead of circular pipes).

The slideable seals 101, 301 were suitable for use with an inner pipe 110 and an outer pipe 111 where the inner pipe is receivable in the outer pipe 111. In alternative embodiments, the slideable seals may be made suitable for use with pipes where both pipes have the same outside diameter. Of course, in such embodiments neither pipe can be received within the other pipe and thus an excess length of one of the pipes cannot be accommodated to the same extent as for the slideable seals 101, 301. However, if the body of the slideable seal has sufficient axial length then some excess length can be accommodated within the slideable seal.

The slideable seals 101, 301 were described as being moulded from EPDM rubber. In alternative embodiments, the slideable seals may be formed from a rigid body (for example injected moulded thermosetting plastic) provided with annular grooves for receiving resilient seals that are received by the annular grooves.

The slideable seals 101, 301 had seal ridges/lips 130, 230 for sealing against pipes 110, 111. In alternative embodiments the slideable seals may have only a single seal ridge at each end instead of a plurality of seal ridges. A plurality of seal ridges is preferred to ensure a good seal although the use of a single seal ridge at each end allows the axial length of the slideable seal to be reduced. Alternative forms may be used instead of seal ridges to seal against the pipes 110, 111; for example seals with a semicircular cross section may be used instead of the relatively triangular cross-section of the seal ridges 130, 230.

Instead of using 0-rings, other fastening devices such as Jubilee (RTM) worm drive hose clips or plastic or metal cable-tie type fasteners may be used to secure the siding seals 101, 301 to the outer pipe 111. However, the use of o-rings is preferred as 0- rings will usually be more cost effective and reduce installation time.

Instead of an annular shoulder 200, one or more radial projections may be used to prevent excessive insertion of the outer pipe 111. For example, instead of a shoulder 200 that is continuous around the interior circumference of the slideable seals 101, 201, a shoulder comprising one or more radially inwardly projecting bumps may be used. Such an embodiment may reduce friction between the inner pipe 110 and the shoulder while still aligning the inner pipe 110 coaxially with the outer pipe 111.

The holes 211 were shown in Figs. I and 2 as being separated by a small distance from the end of the outer pipe 111. In alternative embodiments, the holes are a shape other than circular and/or are not separated from the end of the pipe. In yet further embodiments, the holes do not perforate the pipe but are provided as recesses for engagement with the locating projections 210.

The slideable seals 101, 301 may be supplied with a suitable length of inner pipe 110 and a suitable length of outer pipe 111. The length of outer pipe 111 may be pre-drilled with the holes 211. The slideable seals 101, 301 may also be supplied with a boiler, for example a condensing boiler. For balanced flues, a kit of parts may comprise two slideable seals 101, 301 (one for the, say, 60mm pipe, the other for the, say, lOOm pipe).

The slideable seals 101, 301 may also be used to join sewer pipes or other applications where a seal against a low pressure medium is required.

The slideable seals 101, 301 were described above as having seal ridges 130 and 230 formed about the interior of the sliding seals 101, 301, and as suitable for mounting around the exterior of a pair of telescoping pipes. In alternative embodiments, the arrangement may be turned insideout so that seal ridges are formed on the exterior of the sliding seal.

The sliding seal of such alternative embodiments may be mounted inside a pair of telescoping pipes and would form a seal against the interior walls of the pair of telescoping pipes. Similarly, locating projections may be arranged to project radially outwards from such embodiments. Again similarly, a recess may be provided at the interior of such embodiments to receive an expandable fastening device such as a Jubilee (RTM) worm drive clip. Again similarly, a shoulder may be provided at the exterior of such embodiments.

Claims

1. A slideable seal for forming a seal between two pipes, the slideable seal comprising: an annular body; first seal means towards a first end of the annular body for forming a seal with a first pipe; second seal means towards a second end of the annular body for forming a seal with a second pipe.

2. A slideable seal according to claim 1, wherein the first seal means and the second seal means are both provided at either the interior or the exterior of the annular body.

3. A slideable seal according to claim 2, wherein the first seal means and the second seal means are both provided at the interior of the annular body.

4. A slideable seal according to any one of claims ito 3, wherein the first seal mean is integrally moulded with the annular body.

5. A slideable seal according to any one of claims 1 to 4, wherein the second seal means is integrally moulded with the annular body.

6. A slideabie seal according to any one of claims I to 5, wherein the first seal means is adapted for forming a seal against a first pipe having an annular outer size that is smaller than the outer size of a second pipe.

7. A slideabie seal according to any one of claims 1 to 6, wherein the slideable seal has a generally circular cross-section in a plane perpendicular to a longitudinal axis of the slideable seal.

8. A slideable seal according to any one of claims Ito 7, comprising one or more projections, projecting radially from the annular body, for engaging with one or more corresponding recess means provided in the second pipe.

9. A slideable seal according to claim 8, comprising four projections.

10. A slideable seal according to claim 8 or 9, wherein a recess is defined in the slideable seal for receiving a fastening device such as an 0-ring and thereby urging the one or more projections into the one or more corresponding recess means.

11. A slideable seal according to any one of claims 8 to 10, comprising an 0-ring connected to the slideable seal by a web.

12. A slideable seal according to claim 11, wherein the web is annular.

13. A slideable seal according to claim 11 or 12, wherein the web is dimensioned to allow the 0-ring to be detached by hand from the slideable seal.

14. A slideable seal according to any preceding claim, comprising shoulder means for acting as an end stop for the second pipe.

15. A slideable seal according to claim 14, wherein the shoulder means comprises an annular shoulder.

16. A slideable seal according to claim 14 or 15, wherein the shoulder means and the first seal means are relatively dimensioned so that the first seal means may form a slideable seal against a first pipe of a size sufficient to be aligned by the shoulder means.

17. A slideable seal according to any one of claims 14 to 16 when dependent on any one of claims 8 to 13, wherein the shoulder means and the one or more projections are relatively dimensioned so that they are radially coterminous.

18. A kit of parts comprising: a slideable seal according to any one of claims Ito 17; a first pipe; and a second pipe.

19. A kit of parts according to claim 18 when dependent on any one of claims 8 to 13, wherein one or more corresponding recess means are provided in the second pipe for engaging with the one or more projections.

20. A kit of parts according to claim 19, wherein the one or more corresponding recess means comprise one or more circular holes.

21. A kit of parts according to any one of claims 18 to 20, comprising a boiler.

22. A kit of parts according to claim 21, wherein the boiler comprises a condensing boiler.

23. A slideable seal as herein described and/or with reference to Figs. 1, 2, 3 or 4.