As the need for sanitary valves continues to increase for industries such as semiconductor and biopharmaceutical, radial diaphragm valves are being recognized as highly effective for increased flow, cleanability and low contamination. One such valve is disclosed in U.S. Pat. No. 6,394,417 B1 owned by the assignee of the present invention, the entire disclosure of which is fully incorporated herein by reference. The present invention is directed to additional design options of such a valve.
In accordance with one aspect of the invention, an alternative design to seal a valve actuator piston and diaphragm is provided. In a preferred embodiment of the invention, the diaphragm includes an elongated stem that is threadably or otherwise installed on an actuator piston. The elongated stem is slideably received in a bore formed in the actuator housing, and includes a circumferential recess that receives a seal. The seal provides a backup seal function separating the process fluid from the interior region of the actuator. In a non-manual actuator the seal separates a pressurized portion of the actuator from the diaphragm. The seal may also function as a guide to facilitate alignment of the diaphragm. In one specific but not required embodiment the seal is an o-ring.