Fluid pressure control valve and a system which includes such a valve

Abstract

A fluid pressure control valve and a fluid control system (such as for beverage dispensing) with such a valve has a beverage passage 3, pressure fluctuations in which are detected by a diaphragm 17 to displace a sensing member 15 axially against spring loading 23. Spring 23 reacts on thrust member 22 which is adjustable axially through a cam mechanism 25/26 to vary the biasing force of spring 23. A valve member 20 spring loaded at 21 relative to thrust member 15 normally closes an exhaust port 19 to an air or other gas passage 5 through which gas passes under pressure to be injected into the beverage from passage 3. An increase in beverage pressure in passage 3 displaces sensing member 15 to increase the spring biasing 21 on the closure member 20 and reduce the proportion of air which can escape to atmosphere from passage 5 through exhaust port 19 to provide an increase in air flow into the beverage. A reduction of pressure in passage 3 reduces the spring biasing 21 to permit a greater proportion of air to escape from passage 5 through exhaust port 9 and thereby reduce the proportion of air which is introduced into the beverage. The control valve can include a temperature sensitive unit responsive to temperature of beverage in passage 3 and which reacts to adjust the force of biasing spring 21 independently of pressure in the passage 3. Plunger 51 can be depressed manually to close the exhaust port 19 temporarily and thereby maintain maximum air pressure in the passage 5.