GB2112906A

GB2112906A - Vacuum relief valve

Info

Publication number: GB2112906A
Application number: GB08138920A
Authority: GB
Inventors: James Edward Mcalpine
Original assignee: McAlpine and Co Ltd
Current assignee: McAlpine and Co Ltd
Priority date: 1980-12-29
Filing date: 1981-12-24
Publication date: 1983-07-27
Also published as: GB2112906B

Abstract

A vacuum relief valve for a waste pipe system through which air can be drawn into the system incorporates a pair of concentric valve sealings (4, 6) closeable by a flexible valve element (11) and a support member (15) is provided to give support to the valve element (11) over at least that portion thereof which extends between the valve seatings (4, 6). <IMAGE>

Description

SPECIFICATION Improvements in or relating to relief valves This invention relates to a relief valve and has particular but not exclusive application to pipe systems wherein a vacuum or partial vacuum is liable to be created. In order to compensate for a drop in pressure within such a pipe system it is necessary to provide means whereby external air can have access to the interior of the pipe. This air intake serves to prevent destruction of water traps in waste pipe systems of the type commonly employed in domestic water closets or the like. It has previously been proposed to provide valves for controlling such air intake at the upper end of a pipe which extend above the roof of the building.

One form of vacuum relief valve which has previously been proposed for this purpose is described in British Patent No. 1,433,446. The vacuum relief valve described in the aforesaid British Patent No.1,433,446 includes a valve body defining a valve chamber connectible to a pipe. The pipe can communicate with the valve chamber through an aperture or apertures in an elastomeric annular valve element which normally closes an annular air inlet opening defined by inner and outer concentric valve seatings. The annular valve element of British Patent No. 1,433,446 has its central portion mounted on a hub so that the valve element extends radially outward from the hub so as to be freely cantilevered therefrom.The cantilevered or unsupported portion of the annular valve element extends radially outwards from the inner concentric valve seating and extends across the air inlet opening to overlie the outer concentric valve seating. Accordingly, the annular valve element is unsupported at its critical area where it extends across the air inlet opening.

Consequently, if any deformation takes place in the valve element, the efficiency of the valve is impaired. Furthermore, the arrangement described in British Patent No. 1,433,446 relies on gravity for the closure of the valve and the valve will therefore only operate in a vertical position. It cannot operate if it is disposed at an angle.

An object of the present invention is to provide an improved form of air admittance valve which can operate efficiently without relying on gravity and in which the risk of distortion of the effective valve element is obviated or mitigated.

According to the present invention there is provided an air admittance valve for a waste pipe system or the like comprising a valve body defining a valve chamber therein; a pair of radiallyspaced concentric valve seatings defining an air inlet therebetween; a flexible valve element normally disposed across the valve seatings to prevent egress of air from the pipe system; a valve element support member disposed across and adjacent a face of the valve element, said support member extending at least bridging the space between the two concentric valve seatings; and at least one aperture in the valve element within the inner valve seating to permit communication of the valve chamber with a pipe or the like into which the valve is fitted.

Preferably, spring means are provided to urge the element into engagement with its valve seatings.

An embodiment of the present invention will now be described by way of example with reference to the accompanying drawing in which: Fig. 1 is a partial cross sectional view of an air admittance valve in accordance with the present invention, and Fig. 2 is a plan view of a support member for the valve element of the valve of Fig. 1.

Referring to the drawing, an air admittance valve which acts as a vacuum relief valve in a waste pipe system comprises a valve body portion indicated generally by the reference numeral 1.

The body portion 1 is of annular form and has a screw-threaded portion 2 whereby it can be fitted into a pipe. At its middle portion the body portion 1 reduces at shoulder 3 to form an inner concentric valve seating 4. The valve seating 4 is connected by radial vanes 5 to an outer valve seating 6. The valve seating 6 has integrally secured thereto an upwardly extending sleeve 7.

Towards the lower end of the sleeve 7 is provided a recess within which is held an O-seal 8.

The O-seal 8 serves to retain a valve lid 9.

Within the valve and defined by the upper horizontal (as shown in the drawing) wall of the lid 9 and the interior of the annular sleeve 7 is a valve chamber 10 within which is located an annular valve element 11 which extends across the valve seatings 4 and 6 to prevent inflow of air through air inlet 1 2 between the valve seatings into the valve chamber 10. The valve element 11 is of a flexible elastomeric material such as rubber and has a plurality of angularly spaced holes 13 provided in its central portion. A further hole is provided in the centre of the valve element to receive a projection 1 4 which is integrally secured to a rigid spider-like support member 1 5 for the valve element 11.It will be noted that the support member 15, which is in the form of an annular grid, extends substantially across the air inlet defined between the inner and outer concentric valve seatings 4 and 6 and such support tends to prevent distortion of the flexible valve element over its effective area i.e. where it seals against the valve seatings 4 and 6. Extending upwardly from the support member 1 5 are integral guide rods 1 6 which are received within cooperating sleeves 1 7 formed integral with the lid 9.

Light springs 1 8 surround each of the sleeves 1 7 so as to exert a light minimal pressure on the upper side of the valve element 11 to urge it into engagement with its seatings 4 and 6. It is thought desirable that there should be at least three angularly spaced springs so as to minimise the possibility of distortion of the valve element.

Alternatively a single central spring could be utilised.

In operation of the valve, the valve is fitted into a waste pipe system. When a partial vacuum is created within the pipe system, this partial vacuum is transmitted through holes 13 in the valve element to the valve chamber 10. The reduction in pressure in valve chamber 10 allows atmospheric air through the air inlet 12 to raise the valve element 11 from its valve seatings 4 and 6 to compensate for the partial vacuum. During the movement of the valve element 11 from its seatings, the element 11 with its support member 1 5 is urged against the action of the springs 1 8 and is guided by the telescopic movement of the guide rods 1 6 within the sleeves 1 7. When the pressure is balanced, the valve element returns to its seatings under the combined effect of gravity and the springs 18. It will be appreciated that if the valve is being used in a non-vertical position, the valve element will be returned under the influence of the springs alone. In some cases it may be possible to operate the valve without such springs and to rely merely on the closure of the valve element by means of gravity.

If desired, the lid 9 can be double-insulated against low temperature conditions e.g. by surrounding the lid by a closely enclosing cover of polystyrene or the like and, as will be evident from the drawing, can be readily removed for servicing.

The valve as described above has a wide range of applications but it is envisaged that its principal application will be in a waste pipe system or in a water trap.

Claims

1. An air admittance valve for a waste pipe system or the like comprising a valve body defining a valve chamber therein; a pair of radially spaced concentric valve seatings defining an air inlet therebetween; a flexible valve element normally disposed across the valve seatings to prevent egress of air from the pipe system; a valve element support member disposed across and adjacent a face of the valve element, said support member extending at least bridging the space between the two concentric valve seatings; and at least one aperture in the valve element within the inner valve seating to permit communication of the valve chamber with a pipe or the like into which the valve is fitted.

2. An air admittance valve as claimed in claim 1, in which spring means are provided to tend to urge the element into engagement with its valve seatings.

3. An air admittance valve as claimed in claim 2, in which the spring means comprise a plurality of springs provided at spaced intervals to act against the valve element substantially across the extent of the air inlet.

4. An air admittance valve as claimed in any preceding claim, in which the valve body comprises a body portion to which a lid is fitted, the body portion and a lid defining the valve chamber therebetween.

5. An air admittance valve as claimed in claim 4, in which a plurality of telescopic guide members interconnect the lid and valve element support member to assist in guiding the valve element along its intended path of travel.

6. An air admittance valve as claimed in claim 5, in which the telescopic guide members comprise integral projections or sleeves on that face of the support member opposite the valve element, said projections or sleeves being slidably located in relation to sleeves or projections respectively integrally formed on the inside of the lid.

7. An air admittance valve as claimed in claim 5 or 6, in which spring means are provided to tend to urge the valve element into engagement with its valve seatings, said spring means surrounding each telescopic guide member.

8. An air admittance valve substantially as hereinbefore described with reference to the accompanying drawing.

9. A waste pipe system incorporating an air admittance valve as claimed in any preceding claim.