Patent ID: 8579257

Claim:
A valve assembly, comprising: a valve seat; a piston movable with respect to said valve seat between a closed position and an open position, pressurized fluid flow being inhibited in the closed position and pressurized fluid flow being established in the open position; and means for establishing a fluid-tight seal when the piston is in the closed position and for preventing a blow out condition when the piston is transitioned to the open position, said means comprising an annular sealing member characterized as an O-ring with an elongated circle cross-sectional shape while the sealing member is in an uncompressed state, the cross-sectional shape taken along a plane including a central axis of the sealing member and defined by opposing inner and outer semicircular end surface segments of a selected radius R, and opposing top and bottom linear surface segments there between of a selected length L, L being equal to or greater than five times R, the outer semicircular end surface segment slidingly engaging a cylindrical surface of the valve seat as the piston moves from the closed position to the open position.