Shutoff valve construction particularly for high pressure

摘要

A shutoff valve for high and maximum pressures comprises a housing with an inlet passage communicating with a discharge passage and having a valve seat therebetween which is closable by a differential piston having one face which is seatable on the valve and an opposite face in a first control chamber. The first control chamber is connectable through a first control valve to a bypass which extends to the discharge passage. In addition a second control chamber is located in the bypass passage and it is regulated by a separate second control valve. A separate control member such as a pivotal lever is associated with each control valve and each must be separately operable in order to permit movement of the differential piston off the valve seat to open the flow passage.