GB2053520A - Liquid supply valves - Google Patents

Abstract

A liquid supply valve for maintaining the level of liquid in a reservoir (14) comprises a piston (10) moved by variation of pressure due to variation of the level of the liquid. A conduit (13) extending into the liquid is connected to a chamber (11) on one side of a piston (10) so that the pressure in this chamber increases with rise of level of the liquid and moves the piston to close a restricted passage (7) for inflow of liquid on the other side of the piston. Closure of this passage increases pressure on a piston (4) which is moved thereby to close the inlet (1) through which liquid is supplied to the reservoir. <IMAGE>

Description

SPECIFICATION Improvements in and relating to valves This invention is concerned with improvements in liquid supply valves such as are used to maintain a reservoir filled to a desired level.

The liquid level in a reservoir has hitherto been controlled by a float operating to open or close the supply of liquid. In a known valve of this kind, the float operates a needle valve to open or close a pressure release passage from a chamber on one side of a piston supported by a pair of axially spaced diaphragms and having differing effective pressure areas at its opposite ends, the piston being moved to close a liquid supply port to the valve when the pressure release passage is closed by the needle valve.

An object of the present invention is to provide a liquid supply valve which is operated by variation of the pressure in a chamber connected to a conduit extending into the liquid contained in the reservoir due to variation of the liquid level in said conduit and said reservoir.

From one aspect the invention provides a liquid supply valve comprising a conduit adapted to extend into a liquid of which the level is to be maintained, said conduit leading to a first chamber on one side of a piston, a second chamber on the other side of the piston having an outlet port, a third chamber connected to said second chamber by a restricted passage, a fourth chamber having inlet and outlet ports, said third and four chambers being on opposite sides of a second piston and being connected by a restricted passage, whereby rise in the level of liquid in said conduit increases the pressure in said first chamber to move said first piston to close the restricted passage into said second chamber, thereby increasing the pressure in said third chamber to move said second piston to close the inlet port to said fourth chamber.

From another aspect, the invention provides a liquid supply valve, comprising a valve body incorporating a cylinder and a piston supported therein, sealing means on one face of the piston for closing a liquid supply port to the body, a chamber on the other side of the piston and subject to liquid inlet supply pressure, a restricted passage from said chamber to one side of a second piston supported in a second cylinder, the other side of said piston being connected to a conduit adapted to extend into liquid of which the level is to be maintained whereby pressure increase on said second piston due to rise of liquid level in said conduit moves said second piston to obturate said restricted passage to increase pressure behind said first piston and move it to close said liquid supply port and a liquid port through the body opened to the inlet port upon movement of the second piston away therefrom.

The two pistons may be sealed to the walls of their respective cylinders by flexible diaphragms which may be clamped between separate sections forming the valve body. All of the parts of the valve can be made from plastics material of suitable characteristics and the valve is thus capable of controlling corrosive fluids.

Other parts of the invention are embodied in the preferred form of liquid supply valve which will now be described by way of example, with reference to the accompanying drawing, the single figure of which is a central longitudinal section.

As shown, the liquid supply valve comprises a body 1 5 which in use is mounted in a reservoir 14. An inlet tube 1 leads into a chamber 2 from which extends an outlet 3 into the reservoir 14. A piston 4 is supported by a diaphragm 1 6 forming one wall of the chamber 2 and carries sealing material 1 7 which on movement of the piston 4 to the right in the drawing abuts against the end of the inlet tube to close the valve.

On one side of the piston 4 is a chamber 6 which is connected to the chamber 2 by a restricted passage 5 passing axially through the piston 4. The chamber 6 is connected by a restricted passage 7 to a chamber 8 which has an outlet port 9 communicating with the reservoir.

The passage 7 is larger than the passage 5.

A piston 10 supported on a diaphragm 1 8 separates the chamber 8 from a chamber 11 which is connected by a passage 12 to a pipe 1 3 extending downwardly from the valve body into liquid in the reservoir 14. Movement of piston 10 to the right in the drawing obturates the passage 7.

In the condition shown in the drawing, liquid enters through tube 1 into chamber 2 and passes into reservoir 14. Liquid also passes through the passage 5 into chamber 6 thence through port 7 into chamber 8 and into the reservoir through outlet port 9. The pressure in the inlet pipe is higher than in chamber 2 owing to the liquid having to change directions over the face of the piston 4. As the passage 7 is larger than the passage 5 the pressure in chamber 6 is lower than in chamber 2 so that there is no force tending to move the piston to the closed position.

As the liquid level in the reservoir and so in the pipe 13 rises, pressure is induced in the pipe 13 and through passage 12 into the chamber 11. This forces piston 10 on to the end of passage 7 shutting off flow of liquid chamber 6 to chamber 8; When passage 7 is closed, the pressure in chamber 6 becomes greater than in chamber 2 and piston 4 is forced to close shutting off liquid flow tube 1 into chamber 2. As the piston moves pressure increases through port 5 and decreases in chamber 2 due to the restriction imposed by the closing of the piston.

When the level of liquid drops, the pressure in chambers is reduced thus relieving pressure in chamber allowing passage 7 to open which in turn releases pressure in chamber 6 allowing piston 4 to resume its original position to allow liquid flow from tube 1 to tank 14.

It will be understood that the invention is not restricted to the details of the preferred form described which may be modified within the scope of the accompanying claims.

Claims (3)

1. A liquid supply valve comprising a conduit adapted to extend into a liquid of which the level is to be maintained, said conduit leading to a first chamber on one side of a piston, a second chamber on the other side of the piston having an outlet port, a third chamber connected to said second chamber by a restricted passage, a fourth chamber having inlet and outlet ports, said third and fourth chambers being on opposite sides of a second piston and being connected by a restricted passage, whereby rise in the level of liquid in said conduit increases the pressure in said first chamber to move said first piston to close the restricted passage into said second chamber, thereby increasing the pressure in said third chamber to move said second piston to close the inlet port to said fourth chamber.

2. A liquid supply valve comprising a valve body incorporating a cylinder and a piston supported therein, sealing means on one face of the piston for closing a liquid supply port to the body, a chamber on the other side of the piston and subject to liquid inlet supply pressure, a restricted passage from said chamber to one side of a second piston supported in a second cylinder, the other side of said piston being connected to a conduit adapted to extend into liquid of which the level is to be maintained whereby pressure increase on said second piston due to rise of liquid level in said conduit moves said second piston to obturate said restricted passage to increase pressure behind said first piston and move it to close said liquid supply port and a liquid port through the body, opened to the inlet port upon movement of the second piston away therefrom.

3. A liquid supply valve substantially as described with reference to the accompanying drawing.