GB2090382A

GB2090382A - Vent valve

Info

Publication number: GB2090382A
Application number: GB8138921A
Authority: GB
Original assignee: McAlpine and Co Ltd
Current assignee: McAlpine and Co Ltd
Priority date: 1980-12-29
Filing date: 1981-12-24
Publication date: 1982-07-07

Abstract

An anti-siphon device for a liquid discharge system, comprises valve means (22, 23) moveable between a normally open position in which air can be admitted to the system and a closed position in which the valve means prevents liquid egress from the system on a blockage occurring therein. The valve closure member 22 is mounted on a hollow float 22 which is slidably supported on an apertured inlet conduit 18. <IMAGE>

Description

SPECIFICATION Improvements in or relating to air admittance valves This invention relates to a non-return air admittance valve. In domestic washing machines, dishwashers or similar appliances, it is customary to discharge waste water from the appliance to drain by means of a flexible hose connected towards the base of the appliance. The flexible hose is then led vertically upwards to a height above the top water level in the appliance before being fed loosely into the upper end of a vertical stand pipe. Waste water is fed downwardly into the stand pipe from where it passes to drain via a waste trap. The internal diameter of the upper end of the stand pipe is normally wider than the external diameter of the hose to provide an air gap The purpose of the air gap is to allow the syphon effect which would otherwise be present to be broken.This arrangement, however, results in a system which is not sealed and consequently if a blockage takes place in the waste trap, water can flow back out of the system and overflow from the top end of the stand pipe.

An object of the present invention is to provide means whereby an anti-syphon air break can be provided in the system but which also allows the system to be sealed.

According to the present invention there is provided an anti-syphon device for the liquid discharge system of an appliance, said device comprising a body, a valve chamber within said body, an air inlet into said chamber, valve means moveable between a normally open position in which air can pass through said chamber via said air inlet and a closed position in which the valve means closes to prevent egress of water from the air inlet on liquid flowing into the chamber.

An embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 illustrates diagrammatically an air admittance valve in accordance with the present invention positioned in the water discharge system of a washing machine; Figure 2 is a part sectional view of a first embodiment of air admittance valve for incorporation in the system of Figure 1, and Figure 3 is an alternative embodiment of air admittance valve.

Referring to the drawings, a domestic washing machine 1, is provided with a flexible water discharge hose 2, which is led upwardly to a location as at 2a where the hose is above the normal level of the water in the machine 1. The hose 2 then extends downwardly where it is force-fitted to a connector 3 of a tubular T-piece 4. The other end of the T-piece 4 is connected to a waste trap indicated generally by the reference numeral 5. The T-piece 4 has a tubular leg 6 which projects upwardly to receive, by means of a spigot and socket connection, a one way non-return valve 7.

As shown in Figure 2, the valve 7 comprises a lower body portion 8 within which an upper body portion 9 is removably located. The upper and lower body portions 8, 9 when fitted together, define a valve chamber 10 therein. Within the chamber 10 a floatable ball 11 is supported on spaced integral projections 12 provided on the lower body portion 8.

The lower end of the body portion 8 has an integral tubular outlet 8a by means of which the valve can be mounted in the tubular leg 6 of the T-piece 4.

The upper body portion 9 has an air inlet partially closed by a grid 13 and the wall of the body portion 9 reduces in cross-section towards it upper end i.e. it is frusto-conical. An annular seal 14 of suitable material e.g. elastomeric is positioned within the frustoconical wall towards its lower end so that if the ball 11 rises within the chamber 10, it seals against the seal 14 to prevent fluid egress from the valve chamber 10 to the exterior of the valve.

In operation of the air admittance valve in a system as illustrated, water is discharged from the washing machine and the valve 7 allows air to be drawn in through the air inlet to act as an air break against syphonic action and in this condition the ball 11 of the valve remains, by gravity or alternatively by light spring action, on the projections 12 clear of the annular seal 14therebyallowing airto pass through the air inlet, through the valve 7 and into the system through the leg 6 of the T-piece. If there is a blockage, for example in the waste trap, then water flows up the leg 6 of the T-piece and into the valve chamber 10 causing the ball 11 to be raised into engagement with the annular seal 14 so blocking the passage of water out of the valve through the air inlet. Consequently, a sealed system is provided.

In the alternative embodiment of air admittance valve as shown in Figure 3, the valve comprises upper and lower body portions 15, 16 respectively adapted to be fitted together to define a valve chamber 17 therein.

The lower body portion 16 incorporates an integral upstanding tubular sleeve 18 formed with spaced vertical slots 19. Afloatable cylindrical valve carrier 20 sits loosely over the sleeve 18 to be supported on ribs 21 at a location above the lower ends of the slots 19. The carrier 20 supports an elastomeric seal 22 e.g. of rubber, on its upper face. The seal 22 is adapted to seal against a valve seat 23 formed internally of the upper body portion 15.

The carrier 20 is provided with an integral central spindle 24 which projects upwardly to be received within a bore in a guide sleeve 25 integral with the upper body portion 15 of the valve. Radial vanes 26 extend between the outer periphery of the guide sleeves 24 and the outer wall of the upper body portion 15 to define openings through which air can pass into the valve chamber 17.

The valve of Figure 3 operates in a manner analogous to the manner of operation of the valve of Figure 2. When water is discharged from the washing machine, air is drawn into the valve through the openings between the radial vanes 26, through the valve chamber 17 and through the lower portions of the slots 19 into the system through the leg 6 of the T-piece to act as an air break against siphonic action. If there is a blockage, for example in the waste trap, the water flows up the leg 6 of the T-piece and through the slots 19 to cause the valve carrier 20 to be raised until the seal 22 seals against the valve seat 23 to prevent passage of water out of the valve. During movement of the valve carrier 20 and seal 22, they are guided along the correct path by the spindle 24 travelling with the guide sleeve 25.

Although the above embodiment describes the seal 22 as being provided on the carrier and its co-operating valve seat 23 on the upper body portion 15, it will be readily apparent that the seal can be provided on the upper body portion and the valve seat on the carrier.

The valve means can take any form which is closeable on water entering the valve chamber.

The body of the anti-syphon device of the present invention and the valve element can be constructed of any suitable material, such as synthetic plastics materials e.g. polypropylene.

Claims

1. An anti-syphon deviceforthe liquid discharge system of an appliance, said device comprising a body, a valve chamber within said body, an air inlet into said chamber, valve means moveable between a normally open position in which air can pass through said chamber via said air inlet and a closed position in which the valve means closes to prevent egress of water from the air inlet on liquid flowing into the chamber.

2. An anti-syphon device as claimed in claim 1, in which the body of the device comprises first and second body portions releasably secured together.

3. An anti-syphon device as claimed in claim 1 or 2, in which the valve means comprises a floatable valve element located within the valve chamber and adapted to be raised by liquid flowing into the valve chamber, and seal means disposed between the valve element and the body of the valve chamber to effect sealing of the chamber against egress of liquid therefrom.

4. An anti-syphon device as claimed in claim 3, in which the floatable valve element is supported within the valve chamber so that air can pass freely through the chamber.

5. An anti-syphon device as claimed in claim 3 or 4, in which the seal means is an annular seal disposed within the walls defining the valve chamber and the valve element is a ball.

6. An anti-syphon device as claimed in claim 5, in which the sealing ring is mounted on a frusto conical wall ofthe body.

7. An anti-syphon device as claimed in claim 3 or 4, in which the seal means is provided on the valve element.

8. An anti-syphon device as claimed in claim 3 or 4, in which an apertured conduit is provided within the valve chamber, and the valve element comprises a floatable carrier freely but guidedly supported on said apertured conduit, a seal on said carrier, and a seat within the valve body with which the seal is adapted to engage.

9. An anti-syphon device as claimed in claim 8, in which the apertured conduit is formed by a tubular sleeve having slots therein.

10. An anti-syphon device as claimed in claim 8 or 9, in which the valve element is guided for movement within the valve chamber by a spindle on the floatable carrier which spindle is received within a guide sleeve in the valve body.

11. An anti-syphon device as claimed in any of claims 8 to 10, in which the valve seat is provided on the carrier and the seal is provided on the valve body.

12. An anti-syphon device as claimed in any preceding claim in which the body of the device is formed with a tubular outlet from the valve chamber whereby the device can be operatively mounted in the discharge system of an appliance.

13. An anti-syphon device substantially as herein before described, with reference to any of Figures 1 to 3 of the accompanying drawings.

14. A sealed liquid discharge system for an appliance comprising a tubular conduit intercon necting an appliance and a waste trap, said conduit having mounted therein an anti-syphon device as claimed in any preceding claim.