GB2201304A

GB2201304A - Earth-continuity pipe fitting

Info

Publication number: GB2201304A
Application number: GB08703925A
Authority: GB
Inventors: Robert Nelson Hayward
Original assignee: Heatrae Sadia Heating Ltd
Current assignee: Heatrae Sadia Heating Ltd
Priority date: 1987-02-19
Filing date: 1987-02-19
Publication date: 1988-08-24
Also published as: GB8703925D0

Abstract

A fitting which is, in use, connected to an end of a pipe (13) in fluid-tight manner comprises a body (10) made of non-electrically conducting material, the body (10) having an opening (11) to receive a pipe (13), the fitting providing electrical continuity between the pipe (13) and an earth conductor (27) through a coating (24) of conductive material applied to the body. The body is preferably made of polyacetal plastics and the coating may be flame-sprayed zinc. <IMAGE>

Description

Title: Coated Fitting Description of Invention This invention relates to a fitting, more particularly, but not exclusively, to a plumbing fitting which is, in use, connected to an end of a pipe in fluid-tight manner and to an instantaneous water heater incorporating such a fitting.

Such fittings are used inside instantaneous water heaters and other electrically operated appliances to connect an inlet pipe which is usually made of copper or stainless steel, to the water heater or other apparatus of the appliance to- enable water fed along the pipe to be ducted through the fitting to the apparatus within the appliance.

The fitting and pipework within such appliances are commonly made of a plastic material, but it is a safety requirement that the inlet pipe is connected to an earth terminal.

One proposal for achieving an earth connection using a plastic fitting has been put forward in British specification GB 2022752 in which a conductor strip makes a connection with an inlet pipe when a fluid-tight joint is made between the inlet pipe and the fitting. The conductor is then connected to earth.

The problem with this proposal is that it is necessary for an extra component to be made, namely the conductor strip, and then for the conductor strip to be secured to a body of the fitting which requires an additional assembly step.

An object of the present invention is to provide a new or improved fitting.

According to one aspect of the invention we provide a fitting comprising a body made or substantially made of non-electrically conducting material, the body having an opening to receive an electrically conductive member, the fitting providing electrical continuity between the member and a further conductor through a coating of conductive material applied to the body.

Thus the need to manufacture any additional component is obviated. A coating is simply applied to the body of the fitting so that no additional assembly step is required.

The further conductor may extend from a connection of the fitting to an earthed terminal, and the connection may be provided by an integrally formed part, such as a tab on the body of the fitting, the coating providing a current path between the conductive member and the tab.

The tab may be apertured and the conductor may be connected via a nut and bolt type fastener, or a push-on plug type connection, or any other connection as required.

Alternatively, the further conductor may comprise a further electrically conductive member received in a further opening of the body.

Particularly where the fitting comprises a plumbing fitting, the electrically conductive member and the further electrically conductive member where provided, may comprise pipes to carry fluid, the opening for the electrically conductive member communicating with the further opening of the body via an internal passage means of the fitting to enable fluid flow through the fitting.

The pipe or each pipe is preferably connected to the fitting in substantially fluid-tight manner.

For example, at least one of the pipes, preferably the electrically conductive pipe, may be connected to the body by a conventional compression joint, the body around the opening being threaded to engage with the thread of a connector nut, a compression ring being interposed between the nut and the fitting to provide a fluid-tight seal between the fitting and the pipe.

Alternatively, or additionally, at least one of the pipes, may be connected in fluid-tight manner by a push-in joint with the respective opening for example, of the type in which an 0 ring is provided to achieve a fluidtight seal between the fitting and the pipe.

Where the fitting is used in an appliance to which fluid is fed via the electrically conductive member, the electrically conductive member may comprise a metallic inlet pipe connected in fluid-tight manner with the fitting by a compression joint. An outlet pipe from the fitting may be made of plastic and may be connected by a push-in joint into an outlet opening of the fitting.

The fitting may have a third opening at an alternative position to the inlet opening which third opening may in use, be blanked off with a fluid tight joint, such as may be achieved with a cap nut and sealing washer, or may receive a further pipe as required.

Thus the fitting may provide for alternative inlet positions i.e. the first or third opening to suit the plumbing of a room in which the appliance is situated.

The coating preferably covers substantially the entire external surface of the body although may be selectively applied by masking parts of the body if required. In each case, the coating would have to provide a current path from the electrically conductive member to the further conductor. Where the fitting is a plumbing fitting and the electrically conductive member is connected to the fitting in fluid-tight manner via a compression joint, the 'current path from the electrically conductive member, which need not be in direct electrical contact with the coating, and the coating, may be via an electrically conductive e.g. metallic, compression ring of the joint which engages the electrically conductive member, and an electrically conductive e.g. metallic, nut of the compression joint which engages the compression ring and the thread surrounding the opening of the fitting in which the electrically conductive member is received.

The coating may be applied by spraying for example using a technique known as "flame spraying" in which the coating material is subjected to a flame and molten droplets of the coating material are carried to the fitting.

It has been found that even with a very fine coating of a few thousandths of an inch this enables a high current to pass through the coating from the electrically conductive member to the further conductor. Tests on one sample namely a zinc coated acetyl cpolymer fitting body enabled a current of 50 amps to pass for at least 15 minutes without the failing.

Other conductive materials may be applied by this spraying technique to other plastics to achieve a sufficient coating, although by suitable preparation of the plastic fitting, a coating of conductive material may be applied by other techniques as required.

The invention is particularly applicable to a plumbing fitting.

According to a second aspect of the invention we provide a plumbing fitting having a body made or substantially made of non-electrically conducting material, an opening in the body to receive a first pipe comprising an electrically conductive member, and an opening for receiving a second pipe and passage means through the body for the flow of fluid from the first pipe to the second pipe, and the body having applied thereto a coating of electrically conductive material to provide electrical continuity between the first pipe and a further conductor.

The further conductor may comprise the second pipe or a conductor connected to a part such as a tab, integrally formed with the body, the coating providing a current path from the first pipe to the tab.

The plumbing fitting may have any of the features of the fitting of the first aspect of the invention.

According to a third aspect of the invention, we provide an electrically controlled appliance having a housing, and within the housing a fitting according to the first aspect of the invention which provides electrical continuity between an electrically conductive member which extends through the housing, and an earthed terminal within the housing.

The appliance may comprise a water heater and the electrically conductive member may comprise an inlet pipe.

The invention will now be described with the aid of the accompanying drawing which is a side view partly in section of a fitting in accordance with the invention.

Referring to the drawing, a plumbing fitting comprises a body 10 having an opening II to receive an end of a pipe 13, which in the present example is metallic and therefore electrically conductive.

The pipe 13 is connected in fluid-tight manner to the body using a conventional compression ring 14, and a nut 15, the nut having a shoulder 16 which engages with the compression ring 14 to urge the compression ring 14 into engagement with an internal shoulder 17 of the opening II when the nut 15 is rotated, female threads 18 of the nut co-operating with male threads 19 provided aroundthe opening 11 on the exterior surface of the body 10.

The opposite end of the body 10 is provided by a further similar opening which is blanked off by a cap nut 20 which is not shown in section in the drawings and retains a sealing washer in fluid-tight manner.

If desired, within the opening which is blanked off a filter element may be included, which extends along an internal passage means 21 of the fitting to filter fluid as it passes through the fitting from the pipe 13 to an outlet 22.

The outlet 22 comprises a further opening which receives in a pushfit manner, an outlet pipe 23 which in the present example is a plastic pipe although it will be appreciated that the pipe 23 could be made of metal if required and in either case instead of being a push fit, could be connected in fluid-tight manner to the body 10 by a compression joint in the same way that pipe 13 is connected to the body.

The body 10 is made as a plastics moulding, in the present example, a moulding of acetyl co-polymer and this material is not normally electrically conducting.

However, electrical continuity to provide an earth connection to pipe 13 is achieved through the fitting by virtue of a coating 24 of metallic conductive particles.

The nut 15 is metallic as is the ring 14 and forms an electrical connection between pipe 13 and the coating 24 by virtue of engagement of the nut 15 with the compression ring 14 which is electrically connected to the pipe 13, and engagement of the threads 18 of the nut 15 with the threads 19 of the body 10.

Formed integrally with the body 10 is a tab 25 which has an aperture 26 whereby an electrical conductor 27 may be connected to the fitting in electrical contact with the coating 24 which also is applied to the tab 25.

This is achieved as shown by a nut and bolt fastener, the bolt 28 being received in the opening 26.

Thus any rise in electrical potential of the pipe 13 relative to earth, will result in current passing via compression ring 14 and nut 15 via the engaging threads 18 and 19 and the tab 25 to the conductor 27, the other end of which may be connected to an earthed terminal.

In the present example, the coating 24 comprises zinc particles. The coating covers substantially the entire exterior surface of the body 10 of the fitting including the tab 25, and the threads 19 around opening 13.

The coating 24 is applied by spraying, in a technique known as "flame spraying". In this technique, metal wire is positioned in a combustion flame where the wire melts and an air blast of compressed air removes molten droplets from the wire and projects them onto the surface to be coated.

However, the coating may be applied by other spraying techniques, or by any other method although some surface preparation of the fitting may be required to provide a coating by some methods.

The invention is particularly applied in one example, to an electrically controlled appliance comprising an instantaneous water heater of the type which is used to heat water for showers.

The fitting would be positioned within a housing of the appliance and an inlet- pipe such as pipe 13 would be connected to the fitting as shown, or alternatively, to the opening at the opposite end of the body in place of the blank 20. In this event, a blank would close the opening 11.

Thus the inlet pipe may be connected to alternative positions to suit different plumbing arrangements within a room in which the heater is positioned.

The pipe 23 is an outlet pipe made of plastics material which extends to the water heating apparatus of the appliance. The conductor 27 would be secured to an earth terminal usually within a housing of the water heater.

In another application, instead of a blank 20 closing the opening in the body, a further pipe may be connected to the body by a conventional compression joint such as that used to connect pipe 13 in opening II. This further pipe may be made of metal, plastics, or any other material.

As mentioned above, the coating 24 is applied to the entire exterior surface of body 10 which body is an acetyl co-polymer, and the coating is of zinc particles. Coatings of alternative materials may be applied to suit different types of plastics, and if desired the coating 24 may be selectively applied, parts of the body 10 being masked as the coating 24 is applied.

The features disclosed in the foregoing description, or the accompanying drawing, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, or a class or group of substances or compositions, as appropriate, may, separately or in combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

CLAIMS:

I. A fitting comprising a body made or substantially made of nonelectrically conducting material, the body having an opening to receive an electrically conductive member, the fitting providing electrical continuity between the member and a further conductor through a coating of conductive material applied to the body.
2. A fitting according to Claim I wherein the further conductor extends from a connection of the fitting to an earthed terminal.
3. A fitting according to Claim 2 wherein the connection is provided by an integrally formed part, the coating providing a current path between the conductive member and the connection.
4. A fitting according to Claim 3 wherein the connection is a tab on the body of the fitting.
5. A fitting according to Claim 4 wherein the tab is apertured and the further conductor is connected via a fastener, or a push-on plug type connection.
6. A fitting according to Claim I wherein the further conductor comprises a further electrically conductive member received in a further opening of the body.
7. A fitting according to any one of the preceding claims wherein the fitting comprises a plumbing fitting.
8. A fitting according to Claim 7 where appendent to Claim 6 wherein the electrically conductive member and the further electrically conductive member comprise pipes to carry fluid, the opening for the electrically conductive member communicating with the further opening of the body via an internal passage means of the fitting to enable fluid flow through the fitting.
9. A fitting according to Claim 8 wherein each pipe is connected to the fitting in substantially fluid-tight manner.
10. A fitting according to Claim 9 wherein at least one of the pipes, is connected to the body by a conventional compression joint, the body around the opening being threaded to engoge with the thread of a connector nut, a compression ring being interposed between the nut and the fitting to provide a fluid-tight seal between the fitting and the pipe.
II. A fitting according to Claim 9 wherein at least one of the pipes, is connected in fluid-tight manner by a push-in joint with the respective opening.
12. A fitting according to Claim II wherein the push-in joint is of the type in which an 0 ring is provided to achieve a fluid-tight seal between the fitting and the pipe.
13. A fitting according to any one of Claims I to 5 wherein the fitting is part of an appliance to which fluid is fed via the electrically conductive member, the electrically conductive member comprising a metallic inlet pipe an outlet pipe from the fitting being made of plastic.
14. A fitting according to Claim 13 wherein the inlet pipe is connected in fluid-tight manner with the fitting by a compression joint and the outlet pipe is connected by a push-in joint into an outlet opening of the fitting.
IS. A fitting according to Claim 13 or Claim 14 wherein the fitting has a third opening at an alternative position to the inlet opening.
16. A fitting according to Claim 15 wherein the third opening is in use, blanked off with a fluid tight joint, or receives a further pipe.
17. A fitting according to any one of the preceding claims wherein the coating covers substantially the entire external surface of the body.
18. A fitting according to any one of Claims 7 to 17 wherein the electrically conductive member is connected to the fitting in fluid-tight manner via a compression joint, a current path from the electrically conductive member, being via an electrically conductive compression ring of the joint which engages the electrically conductive member, and an electrically conductive nut of the compression joint which engages the compression ring and the thread surrounding the opening of the fitting in which the electrically conductive member is received.
19. A fitting according to any one of the preceding claims wherein the coating is applied by spraying.
20. A fitting according to Claim 19 wherein the coating is applied by "flame spraying" in which the coating material is subjected to a flame and molten droplets of the coating material are carried to the fitting.
21. A fitting according to any one of the preceding claims wherein the body of the fitting is made from acetyl co-polymer.
22. A fitting according to any one of the preceding claims wherein the coating is zinc.
23. A plumbing fitting having a body made or substantially made of nonelectrically conducting material, an opening in the body to receive a first pipe comprising an electrically conductive member, and an opening for receiving a second pipe and passage means through the body for the flow of fluid from the first pipe to the second pipe, and the body having applied thereto a coating of electrically conductive material to provide electrical continuity between the first pipe and a further conductor.
24. A fitting according to Claim 23 wherein the fitting has any of the features of the fitting according to any one of Claims I to 22.
25. A fitting substantially as hereinafter described with reference to and as shown in the accomponying drawings.
26. An electrically controlled appliance having a housing, and within the housing a fitting according to any one of Claims I to 20 which provides electrical continuity between an electrically conductive member which extends into the housing, and an earthed terminal within the housing.
27. An appliance according to Claim 25 wherein the appliance comprises a water heater and the electrically conductive member comprises an inlet pipe.
28. An appliance substantially as hereinafter described with reference to the accompanying drawings.
29. Any novel feature or novel combination of features disclosed herein and/or as shown in the accompanying drawings.