Diaphragm valves

A diaphragm operated valve, comprising:

• a valve body having an inlet and an outlet;
• and an inner wall within said valve body;
• a valve seat between the inlet and outlet;
• a rigid, reciprocable valve closure member movable in the valve body toward and away from the valve seat and having a hard, rubber-like seating surface for movement into and out of closing relationship with the valve seat;
• and a separate, annular valve-operating diaphragm of flexible, rubber-like material having an inner peripheral portion with an inner edge thereon and an outer peripheral portion with an outer edge thereon and secured around its inner edge to the closure member and around its outer edge to the valve body inner wall so that a chamber is defined between the inner wall and the diaphragm and closure member which chamber is located between the inlet and outlet;
• the closure member having an opening defined therein leading into the chamber;
• pilot valve means in fluid communication with said chamber to be operatively connected with said diaphragm to control application of fluid pressure to said diaphragm to operate said valve;
• the inner peripheral portion of the diaphragm having a thickness substantially greater than the outer peripheral portion thereof so that the diaphragm outer portion is thin relative to the diaphragm inner portion, the differences in thickness from the outer peripheral portion to the inner peripheral portion being gradual and free of stress-inducing sudden transitions;
• the valve body inner wall having an extension directed toward the closure member from the inner wall and located between the diaphragm and the inlet to define a ledge positioned to contact and accommodate the thin outer portion of the diaphragm when the valve is closed and fluid pressure is applied to the diaphragm for supporting the diaphragm thin portion when the valve is closed and pressure is applied to the diaphragm.