Patent ID: 7422029

Claim:
A check valve comprising: a valve body having an upstream side, a downstream side, and a valve flow channel that extends between the upstream and downstream sides; a flapper rotationally mounted on the valve body and movable between a closed position, in which the flapper at least substantially seals the valve flow channel, and an open position, in which the flapper at least substantially unseals the valve flow channel; and a damping mechanism mounted on the flapper and configured to slow movement of the flapper when the flapper is approaching the open position and when the flapper is approaching the closed position, the damping mechanism comprising: a main body having at least an inner wall that defines a chamber having fluid therein, the main body coupled to the flapper and configured to move therewith; and a piston disposed at least partially within the chamber, the piston configured to move within the chamber in a direction opposite the direction of movement of the main body when the flapper approaches the open position and when the flapper approaches the closed position, to thereby compress the fluid in a section of the chamber and slow movement of the main body and the flapper.