Diaphragm valve with total valve cavity evacuation

A valve comprising:

• a fluid block that comprises a process fluid inlet and a process fluid outlet, a fluid block that comprises an actuation fluid cavity, and valve assembly disposed in an assembly cavity formed by fluid block and fluid block;
• a valve cavity in said assembly cavity, said valve cavity formed between a diaphragm spacer and a valve seat in said assembly cavity;
• a plunger in said assembly cavity, said plunger comprises a plunger cavity formed in a plunger stem, and a plunger fluid flow passage in said plunger, said plunger fluid flow passage fluidly connecting the actuation fluid cavity and plunger cavity;
• a diaphragm assembly in said assembly cavity, said diaphragm assembly comprises diaphragm and a boss, said diaphragm assembly secured by said diaphragm spacer and said fluid block in said assembly cavity and fluidly separating said valve cavity into a process fluid side and an actuation fluid side, said boss coupled to said plunger stem through a central passage of the diaphragm spacer, said boss comprises a fluid flow passage formed therethrough that provides fluid communication between activation fluid cavity, plunger cavity, and the actuation fluid side of said valve cavity.

A valve comprising:

• a valve assembly disposed in an assembly cavity formed between a valve plate and fluid block, said fluid block includes an inlet fluid flow passage and an outlet fluid flow passage open to assembly cavity through valve seat of fluid block;
• a valve cavity is formed in a portion of assembly cavity between a diaphragm spacer and valve seat in fluid block;
• said valve assembly further comprises a diaphragm assembly, said diaphragm assembly has diaphragm coupled to boss, said diaphragm spacer disposed between an upper surface of diaphragm and a plunger disposed in assembly cavity, said diaphragm assembly captured and retained in the valve assembly in cooperation with diaphragm spacer and fluid block;
• boss of diaphragm assembly is coupled to a plunger through a central passage of diaphragm spacer, a stem of plunger extends through the central passage of diaphragm spacer and is coupled to boss of diaphragm assembly;
• a pneumatic cavity disposed in a portion of assembly cavity between the back side of plunger and valve plate, said pneumatic cavity communicates with a pressure source through fluid flow passage in valve plate;
• said plunger comprises a fluid flow passage that provides fluid communication between a plunger cavity formed in the plunger stem and the pneumatic cavity, boss of diaphragm assembly comprises a fluid flow passage formed therethrough, that includes an opening to plunger cavity and is fluidly connected to an opening in the boss that is in fluid communication with the back side of diaphragm whereby actuating fluid communicates between plunger cavity and an actuation fluid side of valve cavity.