GB2039345A - An improvement in or relating to float valves - Google Patents

Abstract

A float-operated cistern supply valve has an outlet passage 16 opening upwardly and communicating with a cap 46 which contains a valve element 50 and leads to a discharge outlet. When water is being discharged from the main valve the valve element 50 closes an opening 52 to atmosphere but if a sub-pressure develops in a supply main whilst the valve is open the valve element 50 moves to a position in which it acts as a check valve against the flow of water back into the main valve by re-opening the opening to atmosphere and closing the passage 16. <IMAGE>

Description

SPECIFICATION An improvement in or relating to float valves The invention relates to float valves of the kind including a valve seat and a valve member mounted in a valve chamber for movement towards and away from the seat to open and close the valve in accordance with movements of the float. Such valves, which hereinafter will be referred to as "of the kind described", are commonly used in flushing cisterns and other water tanks for controlling the water inlet to admit water when the level in the tank falls below a pre-determined height. One type of valve of the kind described, commonly referred to as of the "Portsmouth" type, is described in B.S.S.

1212, Part 1. This type of valve comprises a housing having a chamber in which is axially slidable a plunger having a valve closure at one end for engaging an inlet valve seat at one end of the chamber, the plunger being engaged by one end of a bell-crank lever pivoted to the housing intermediate its ends and carrying a float at its other end. Upward movement of the float urges the plunger towards the valve seat and the arrangement is such that when the float is at the maximum desired water level the closure member is forced against the inlet valve seat to close off the flow of water into the tank. When the water level subsequently falls the float drops with it and moves the plunger away from the inlet valve seat so that water is again admitted to the tank.

Another type of valve of the kind described is the subject of B.S.S. 1212, Part 2, and comprises a housing having a chamber in which a diaphragm member is disposed and is capable of engaging an inlet valve seat when acted upon by an axially slidable plunger, the plunger again being under the control of a float in the manner described above. It is to this latter type of valve in particular that the invention relates.

To promote silence in operation of a valve of the kind described the water usually leaves the valve chamberthrough a silencing pipe which extends to the bottom of the cistern or other tank in which the valve is fitted, preferably below the level of a water outlet, so that its lower end is always or nearly always submerged. However, with this arrangement, and in the absence of special precautions, if a sub-pressure (that is to say a vacuum or pressure below atmospheric) exists in the water supply main, due for example to an upstream burst or draining of a main and the float valve opens due to a drop in the water level in the tank, water can be siphoned back into the supply main. This can of course be a danger to public health.

According to the invention, there is provided a valve of the kind described and having an outlet passage which opens upwardly from the valve chamber, the outlet passage communicating with a cap element containing a movable valve element, the arrangement being such that when water is being discharged from the valve into the cistern or other tank in which the valve is fitted the valve element closes an opening to atmosphere in an upper part of the cap element and water is able to flow freely to a silencing pipe communicating with said cap element, whereas, if a sub-pressure should develop in the water supply main whilst the valve is open the valve element moves to a position in which it acts as a check valve against the flow of water into the valve and simultaneously acts as an anti-vacuum valve by re-opening the opening to atmosphere in the upper part of the cap element.The valve element may be constituted by a spherical ball-member made of lightweight plastics material. On the other hand, the valve element may be constituted by a flexible diaphragm.

In order that the invention may be fully understood and readily carried into effect, the same will now be described, by way of example only, with reference to the accompanying drawings, of which: Figure 1 is a sectional view of a float valve embodying the invention, Figure 2 is a sectional view on the line 2-2 in Figure land Figures 3 to 5 are views similar to Figure 2 which illustrate possible modifications which will be referred to.

Referring now to Figures 1 and 2 of the drawings, the valve there illustrated comprises a generally tubular body 10 to one end of which is connected an inlet pipe 12. The body is bored out to form a valve chamber 14 and has an outlet passage 16 opening upwardly from the valve chamber. As shown in Figure 2, the outlet passage communicates with a silencing pipe 18 which extends to the bottom of the cistern or other tank in which the valve is fitted.

A valve seat element 20 has a flange portion which engages a shoulder 22 in the valve chamber 14, being clamped therein by an end of the inlet pipe 12 and a clamping nut 24 which engages a peripheral flange formed on said pipe. A flexible diaphragm 26 is disposed in the bore of the body and has a thickened central portion 28 for closing an axial bore 30 extending through the valve seat element. The diaphragm 26 is clamped in position by means of an end cap 32 retained in position co-axially of the valve body by a screwthreaded collar 34.

A plunger 36 extends slidably through a central hole in the end cap 32 and abuts at its inner end, as shown, against the central portion of the flexible diaphragm. The outer end of the plunger is acted upon by a lever 38 which is pivotally connected between lugs formed on the collar 34 by a pivot pin 40. The lever is connected to a rod 42 which carries a float 43. The arrangement is such that lowering or raising of the water in the cistern or other tank in which the valve is fitted respectively opens or closes the valve.

Referring again in particularto Figure 2, it will be seen that the outlet passage 16 which opens upwardly from the valve chamber is screwthreaded and receives a lower portion of a screwthreaded sleeve 44 the upper portion of which provides a screwthreaded spigot for the attachment of a cap element 46. An elbow piece 48 is connected to a branch pipe formed on the cap element and the silencing pipe 18 depends from said elbow piece.

It will be seen that the upper end of the sleeve 44 is provided with a part-spherical seating on which a spherical ball member 50 can seat itself as shown in full lines in Figure 2. However, the ball member, which is made of a lightweight plastics material, is free to move vertically within the cap element and, as shown in chain-dotted lines, is capable of closing off communication to a cross port 52 at the upper end of the cap element when displaced to a raised position.

The device illustrated in Figure 2 constitutes a combined check valve/anti-vacuum valve which is designed to prevent water being siphoned back into the supply main if the latter is subjected to a sub-pressure. The arrangement is such that when water is being discharged into the cistern or other tank in which the valve is fitted, the flow of water raises the ball member to the position in which it is shown in chain-dotted lines, closing the cross port 52 and opening the silencing pipe 18 to the flow of water. If a sub-pressure should suddenly be brought about in the water supply main, the ball member is immediately caused to seat itself on the seating at the upper end of the sleeve 44 to act as a check valve against the flow of water back into the valve (which if the tank is empty or only partially full will still be open).At the same time, in moving away from the cross ports 52 the ball member allows the entry of air into the silencing pipe, thus acting as an antivacuum valve.

In Figure 3, there is illustrated a modified form of check valvelanti-vacuum valve in which the sleeve 44 has been replaced by a seat holder 54 within which is located a resilient seating ring 56 on which the ball member 50 can seat itself as shown. In addition, a resilient sealing ring 58 is located at the upper end of the cap element 46 so that the ball member can close communication with the cross ports 52 without leakage when water is being discharged from the valve through the silencing pipe.

Referring now to Figure 4, in a rather different design of check valvelanti-vacuum valve a cap element generally indicated 60 is constituted by a seating member 62 having screwthreaded connec tion with the outlet passage 16 from the valve chamber and by a cover element 64 having screw threaded connection with said seating member. A flexible diaphragm 66 is located within the cover element by a screw 68 and the arrangement is such that when water is being discharged from the valve into the cistern or other tank in which the valve is fitted, the flexible diaphragm is held flat against an upper surface of the cover element to close off a plurality of openings 70 as shown by the chain dotted lines.On the other hand, if a sub-pressure should develop in the water supply main whilst the valve is open the flexible diaphragm is immediately pulled down onto an annular seating surface 72 within the cap element to act as a check valve against the flow of water back into the valve and to act as an anti-vacuum valve by re-opening the plurality of openings 70.

In yet a different design of check valve/anti vacuum valve illustrated in Figure 5, a flexible diaphragm 74 has an annular outer portion which is clamped between the two parts which in this case constitute the cap element 60, that is to say between an upstanding annularwall portion of a seating member 76 having screwthreaded connection with the outlet passage 16 from the valve chamber and a cover element 78. The flexible diaphragm 74 has a central closure element 80 which is surrounded by a plurality of holes 82. The arrangement is such that when water is being discharged from the valve into the cistern or other tank in which the valve is fitted, the central closure element of the diaphragm closes the opening 52 in the cover element and water is able to flow freely through a number of holes 84 in the upstanding wall portion of the seating member 76 and into the silencing pipe. If a sub-pressure should develop in the water supply main whilst the valve is open, the flexible diaphragm is immediately pulled down so that its central closure element seats itself on the upstanding central spigot portion 86 to act as a check valve against the flow of water back into the valve and to act as an anti-vacuum valve by re-opening the opening 52 in the cover element so that the silencing pipe is able to communicate to atmosphere.

Various other modifications could be made to the valve described without departing from the scope of the invention, particularly to the manner in which the check valve/anti-vacuum valve is constructed and connected into the outlet from the valve chamber.

Claims (4)

1. A valve of the kind described and having an outlet passage which opens upwardly from the valve chamber, the outlet passage communicating with a cap element containing a movable valve element, the arrangement being such that when water is being discharged from the valve into the cistern or other tank in which the valve is fitted the valve element closes an opening to atmosphere in an upper part of the cap element and water is able to flow freely to a silencing pipe communicating with said cap element, whereas, if a sub-pressure should develop in the water supply main whilst the valve is still open the valve element moves to a position in which it acts as a check valve against the flow of water back into the valve and simultaneously acts as an anti-vacuum valve by re-opening the opening to atmosphere in the upper part of the cap element.

2. A valve according to claim 1, in which the valve element is constituted by a spherical ball member made of a lightweight plastics material.

3. A valve according to claim 1, in which the valve element is constituted by a flexible diaphragm.

4. A valve constructed, arranged and adapted to operate substantially as hereinbefore described with reference to and as illustrated by the accompanying drawings.