Reversible check valve

Claim 1

In a reversible check valve: a. a valve body defining a pair of end passageways made to be connected to fluid-conducting pipes, the valve body having a central chamber communicating with the end passageways thereof; b. a valve plug rotatably mounted in the chamber and having a port extending therethrough, the port being located so as to be aligned with the end passageways in communication therewith, upon turning the plug into either of two predetermined settings, whereby fluid may flow through the passageways and port in either direction; c. the plug being provided with an annular seat in its port, and a swingably mounted check valve flap carried by the plug and disposed in the port thereof, the flap being movable into closed relation with the seat to prevent flow of fluid in one direction, the flap being swingable into open position with respect to the seat to permit fluid flow in the opposite direction, the direction of fluid flow depending upon the predetermined setting of the plug selected; d. a counterweight provided on the flap and projecting outwardly in a radial direction beyond the rim of the flap and arranged to increase the total surface area against which back pressure of the fluid will act in urging the flap to close upon the seat, the counterweight being sufficiently heavy to prevent chattering of the flap; and e. the flap being secured at its top to the plug by a horizontal journal pin, the flap defining opposite faces, one face being movable against the seat, and the counterweight being disposed on tHe other face of the flap in outwardly offset relation with respect to a vertical plane passing through the journal pin, the offsetting being in a direction away from the seat to urge the counterweight and flap toward the seat by gravity.