GB2187534A

GB2187534A - Gas taps

Info

Publication number: GB2187534A
Application number: GB08605205A
Authority: GB
Inventors: Garry Mcardle
Original assignee: Concentric Controls Ltd
Current assignee: Concentric Controls Ltd
Priority date: 1986-03-01
Filing date: 1986-03-01
Publication date: 1987-09-09
Anticipated expiration: 2006-03-01
Also published as: GB2187534B

Abstract

A gas tap comprises a rotary tapered plug 14 sealed in its bore by an "O" ring and/or a spring effective between the plug and a stationary body part. Preferably an "O" ring 28 seals the junction of plug and bore, and a compression spring 32 holds the "O" ring in place and also serves to hold the plug in place. This enables a particularly strong spring to be used without increasing the pressure necessary to displace the actuating stem 22 axially as may be necessary before the stem is free to be turned. <IMAGE>

Description

SPECIFICATION Gas tap This invention relates to a gas tap of the well known kind in which a taper plug seats in a complementary bore and is turned angularly relative to that bore to control the flow of gas through the plug. For this purpose, the plug is bored radially and possibly also axially, and/or grooves are provided in the outer surface of the plug, and the body provided with the bore has at least one inlet and an outlet so that a communication path or flow path for the gas can be opened or closed according to the position of the plug in the body.

The plug is turned by a stem, usually extending axially of the plug from its larger end.

The stem may carry a knob or lever for example to facilitate turning.

The problem exists that if lateral pressure is applied to the stem it tends to displace the plug laterally and this may allow a seepage or leakage of gas from the inlet between the plug and the bore and to the exterior of the tap. This can result in a fire or explosion.

Many gas taps of the kind referred to have the stem made as a separate component from the plug, and with a spring located between the stem and plug so as to urge the plug into good sealing contact with the bore. But the same problem exists.

What is possibly an obvious solution to the problem at least in the case where the stem and plug are separate components, is to increase the spring pressure so as to urge the plug ever more tightly into sealing engagement with its bore. But the secondary purpose of that spring is to hold the stem in a particular angular position or in one of a range of angular positions, for example by association of a radial peg on the stem with a mating cut-out or formation of the body. The stem has to be displaced axially against the spring to release the peg and enable the tap to be turned from the off position to an on position, which is itself a required or desirable safety factor.But the British Standard Specification on this subject sets a limit to the spring pressure, in the interests of making taps operable by the old and feeble or arthritic people, and even with the maximum pressure possible according to the B.S.S. the same problem of lateral loading causing leakage risk still exists.

The object of the present invention is to solve this problem.

In accordance with the invention, the taper plug of a gas tap is sealed in its bore by means of an "0" ring and/or by means of a spring urging the plug into sealing engagement and effective between the plug and a stationary body part.

"0" rings are known in gas taps, but not, so far as the present inventor is aware with taper plugs. Hitherto their use has been confined to taps of a different operating characteristic not employing the taper.

Where the spring is used alone, to carry out the invention, it will not affect the pressure required on the operating spindle because it not effective between the operating spindle and plug, but between the plug and another part of the tap.

Preferably the "0" ring and spring are used together.

According to a feature of the invention, the plug is provided with a cylindrical tubular sleeve-like extension having a radially located slot, the stem is received in that sleeve and has a peg engaged in that slot so that the stem can turn the plug, and the "0" ring is a push fit on that sleeve.

One presently preferred embodiment of the invention is now more particularly described with reference to the accompanying drawing wherein the sole figure is a fragmentary sectional elevation of a gas tap according to the invention.

In the drawing, the gas tap comprises a body 10 formed with a taper bore 12 in which seats a taper plug 14. The plug has a cylindrical sleeve-like extension 16 formed with an axially extending slot at one radial position. The slot receives a peg 20 carried by a stem 22 which terminates in a knob or the like (not shown) for turning the stem angularly and hence turning the plug angularly.

The conventional spring means urging the stem 22 in the direction of the arrow A to engage a mating formation is not shown.

It will be noted that there is a generous and perhaps exaggerated clearance between the stem 22 and the interior of the sleeve 16 with the object of ensuring that if a lateral load is applied to the stem 22, for example to the outer and not shown end, such force has the minimum effect on the plug. But in view of the necessity for the pin 20 to contact the plug in order to turn it, it is conceivable that in some direction such a lateral force will be received by the plug tending to displace it laterally and cause leakage for example passing from the inlet 24 to escape in the direction of the arrow 26 to the exterior of the tap.

According to the invention this leakage is prevented by a secondary seal means.

In one possibility, an "0" ring 28 is provided made of conventional elastomeric material to prevent leakage past the top of the plug 14 towards the arrow 26. This "0" ring could be held in place by being located partly in an interior groove defined by one or other or both of the body and/of the plug. In the iliustrated embodiment it is a push fit onto the sleeve 16 and into the interior of the generally cylindrical and tubular extension 30 of the body, and is maintained in position by a helical compression spring 32 trapped between an end plate 34 and the "0" ring itself. It may be desirable to impose a shim-like washer between the spring and the "0" ring, although by using a helical spring wound from a flat section material with an end coil which is contained in a plane normal to the axis of the stem 22, such a washer may be unnecessary. It will be appreciated that the spring holds the "0" ring in position to maintain the seal, because if the "0" ring is allow to drift in the direction of the arrow A so as to overlap the groove 18, a leakage path would be reopened. The groove 18 is appropriately short and not over the full length of the sleeve 16 for this purpose. It will also be appreciated that the spring may be made of any required strength and force without affecting the force that is necessary to displace the stem 22 from the mating formation.

According to the invention the spring can be arranged to act directly on the plug without an "0" ring, for the purpose of maintaining the plug in sealing contact without making the force required to displace the stem undesirably high.

Claims

1. A gas tap in which a taper plug seats in a complementary bore and is turned angularly relative to that bore to control the flow of gas through the plug, in which the taper plug is sealed in its bore by means of an "0" ring and/or by means of a spring urging the plug into sealing engagement and effective between the plug and a stationary body part.

2. A gas tap as claimed in claim 1 wherein the plug is provided with a cylindrical tubular sleeve like extension having a radially located slot and a stem is received in the sleeve and has a peg engaged in the slot for turning the plug, and said "0" ring is a push fit on said sleeve.

3. A gas tap as claimed in claim 2 wherein the spring is a helical compression spring and one end of said spring abuts the "0" ring to seal between the plug and the bore in which the plug is located.

4. A gas tap substantially as described with reference to the accompanying drawing.

Amendments to the claims have been filed, and have the following effect: Claims 1, 3 above have been deleted or textually amended.

New or textually amended claims have been filed as follows: Claim 4 above has been re-numbered as 3.

1. A gas tap in which a taper plug seats in a complementary bore and is turned angularly relative to that bore to control the flow of gas through the plug, in which the taper plug is sealed in its bore by means of an "0" ring held in place by a spring which is effective between "0" ring and a stationary body part.