Patent ID: 8028712

Claim:
A diaphragm controlled bypass valve comprising: a first valve housing having an inlet, a first outlet and a first flow pathway defined between said inlet and said first outlet; a needle valve pin disposed at least partially within said first flow pathway, said needle valve pin having an open position in which flow is allowed between the inlet and the first outlet; a valve seat disposed within said first valve housing configured to receive a portion of said needle valve pin to close said first flow path; a second valve housing connected to said first valve housing; a diaphragm extending radially within said second valve housing, said diaphragm and said second valve housing defining a first chamber there between; a second pressure chamber defined between said diaphragm and said first valve housing; a second flow path defined from said inlet to a second outlet, said second flow path exposed when said needle valve pin is in said open position; a relief housing threadedly engaged within said second outlet; and a relief piston disposed within said relief housing and communicating with a lower section of said needle valve pin, said relief piston configured to open and close said second flow path.