DIAPHRAGM VALVE FOR LIQUIDS

A diaphragm valve for liquids wherein a cylindrical valve body has a surface recess at one end which receives a resilient valve member of rubber-type material of conforming size. An inlet port from a supply duct and an outlet port to a discharge duct are located in the valve body recess in spaced relation with the recess walls and bottom engaged by the valve member. A retainer holds the valve member in the recess and applies sufficient pressure on the marginal portion of the valve member to establish a liquid-proof seal between the valve member and valve body which exists at least at low liquid pressure. The resilient valve member responds to liquid pressure within the valve, and the seal with the valve body is enhanced in proportion to liquid pressure, giving the valve a self-sealing characteristic over a wide range of liquid pressures. A movable actuator has a cam surface which positions the resilient valve member in relation to the inlet port, closing the port in one position, and in other positions varying the spacing between the valve member and port for varying the rate of flow through the valve. The various parts of the valve, including the actuator, are preassembled economically, and the valve is installed at the point of use as a unit, thereby avoiding any installation step, such as a conventional compression seal, which might permit leakage in the valve.