Patent ID: 7500619

Claim:
A flow stop valve to control fluid flow through a conduit: a valve head adapted to move between an open and closed position, respectively unblocking and blocking fluid flow through a conduit; a lost motion piston and cylinder assembly coupled to the valve head for moving the valve head between the open and closed positions, the cylinder assembly having a piston cyclically moveable within a cylinder between an upper and a lower position for moving the valve head between the open and closed positions, respectfully; a fluid flow path extending between the cylinder below the piston and a portion of the conduit located downstream of the valve head; a first flow control device disposed in the fluid flow path for limiting the rate of flow of fluid through the fluid flow path when the piston is moving downwardly within the cylinder to control the time during which the valve head is in the closed position; and a second flow control device disposed in the fluid flow path for limiting the rate of flow of fluid through the fluid flow path when the piston is moving upwardly within the cylinder to control the time during which the valve head is in the open position.