Patent ID: 8651139

Claim:
A valve comprising: a body having an inlet portion, an inlet port, an outlet portion and an outlet port; a flexible and resilient diaphragm defining an aperture and a seat, said diaphragm disposed between said inlet port and said outlet port and separating said inlet portion from said outlet portion; and a plug; wherein said plug is movable between a first position in which said plug is free of said seat, a second position in which said plug is engaged with said seat and substantially closes said aperture, and a third position in which said plug is engaged with said seat and substantially closes said aperture and substantially deflects a portion of said diaphragm away from said outlet portion so that a free volume within said outlet portion with said plug in said third position is substantially greater than the free volume within said outlet portion with said plug in said second position; and wherein said body and plug are configured to allow flow of a process material over said plug and not through said plug.