High pressure diaphragm valve

A valve comprising:

• a valve body defining a valve with a first interior wall having a first fluid port extending therethrough to the exterior of the body;
• a flexible metal diaphragm sealing the chamber and positioned to extend across the chamber at a location spaced from the first wall and aligned with the first port;
• a seat assembly associated with the first port for cooperation with the diaphragm for controlling flow through the first port, the seat assembly including a resilient annular seat ring positioned in the chamber surrounding the first port and having a seal surface facing the diaphragm, a retaining ring member closely encircling the seat ring to limit radial outward expansion of the seat ring when engaged by the diaphragm and maintain it located relative to the first port, a rigid metal sleeve closely received within the seat ring and extending from the first wall to adjacent the seal surface to limit radial inward deflection of the seat ring when engaged by the diaphragm;
• actuating means for selectively deflecting the diaphragm into engagement with the seal surface;
• and,
• the seal surface being contoured to have a concave shape which generally corresponds to the natural shape and normal deflection pattern of the diaphragm when it is moved into a position of engagement with the seal surface to assure maintenance of the sealing relationship and prevent unnecessary deflection and strain on the diaphragm to thereby provide an extended life of the diaphragm.