Check valve having self energizing seal

Claim 1

A check valve comprising: a. a body having a substantially circular first opening therethrough for the flow of fluid, and parallel faces perpendicular to the first axis of said first opening, one of said faces being an upstream face, and the other a downstream face, said body adapted to be clamped between spaced parallel pipe flanges; b. a second cylindrical opening through said body, the second axis of said second opening perpendicular to said first axis, and displaced a selected distance from said first axis in a direction parallel to said faces, and shaft means journaled in said second opening; c. circular ring seal means having a seating surface inserted into said body on said upstream face, said seal ring means comprising a ring of rigid material, the seating surface of which comprises a conical surface, said conical surface tapering toward said upstream face, and tangent to a sphere having a center at the point where said first axis intersects a perpendicular plane passing through said second axis; d. disc means rigidly fastened to said shaft means and having a circular face, and conical tapered edge, the angle of said conical taper being the same as that of said seating surface; e. a circumferential rectangular groove in said tapered edge, the base of said groove cylindrical, and coaxial with said disc, the walls of said groove perpendicular to the cylindrical base of said groove, the plane through the center of said groove displaced a selected distance along said first axis from said perpendicular plane toward said upstream face; and f. O-ring means in said groove; whereby when said shaft is turned so that the plane of said disc is parallel to the plane of said ring seal means, said O-ring will press against said seating surface and seal the fluid passage through said first opening.