Fluid control valve with diaphragm tensioning geometry

A fluid control valve, comprising:

• a metallic body, including:
• a process surface, including:
• a central portion;
• a body clamping surface adjacent the central portion;
• and a body step between the central portion and the body clamping surface, the body step including an internal corner and an external corner;
• at least one inlet orifice communicating with the process surface;
• at least one outlet orifice communicating with the process surface;
• an inlet port disposed in fluid communication with the at least one inlet orifice and adapted to be coupled in fluid communication with a fluid at a process pressure;
• and an outlet port disposed in fluid communication with the at least one outlet orifice;
• a metallic cap including a reference surface and a reference port disposed in fluid communication with the reference surface, the reference port adapted to be coupled in fluid communication with a fluid at a predetermined reference pressure, wherein the reference surface includes:
• a cavity;
• a pressure pad outboard of the cavity;
• a cap clamping surface;
• and a cap step between the pressure pad and the cap clamping surface, the cap step including an internal corner and an external corner;
• and a metallic diaphragm constrained between the body and the cap and arranged such that, in response to the process pressure being higher than the reference pressure, a fluid flow path will be open from the at least one inlet orifice to the outlet orifice, and in response to the reference pressure being higher than the process pressure, the flow path will be closed.