Pneumatically operated valve with overpressure protection - includes auxiliary chamber with diaphragm in control line regulating inlet according to operating piston movement

摘要

The valve has a cylinder (20) containing a piston (23) mounted on top of the valve spindle (24) which is lifted to open the valve. Between the piston and a diaphragm (61) forming an auxiliary chamber (60) inside the top cover (21) of the cylinder is a return spring (27). Air connected by an inlet line (3) to a supply valve (7) on top enters the auxiliary chamber, then passes through an external line (66) to the chamber (28) under the piston to lift it. After the piston has travelled for a required distance, the pressure in the auxiliary chamber acts on the diaphragm to control a spring-loaded valve member (70) in the supply valve to cut off the supply. The cylinder consists of two telescopic halves (220,201) with flanges connected by regulating screws (202) to adjust the piston travel.