Patent attributes
A check valve comprises a valve housing defining a pair of valve openings, a pair of flappers pivotably mounted for rotation relative to the housing between an open position in which they permit fluid flow through the respective valve openings and a closed position in which they prevent fluid flow through the valve openings, and a stop pin extending across the valve such that the flappers will contact the stop pin in their open positions. Each flapper comprises a primary flapper element and a secondary flapper element, each pivotally mounted to a hinge pin extending across the valve. The primary flapper element further comprises a flapper opening formed therethrough. The secondary flapper element is pivotally mounted to the hinge pin such that it may rotate relative to the primary flapper element for opening or closing the flapper opening.
