Ball valve having retractable sealing member

This invention relates to valves for controlling the flow of fluid and more particularly to a valve in which a closure member rotates between opened and closed positions in which the sealing member between the valve body and closure member engage only upon the application of exterior pressure unrelated to the pressure within the valve. A ball valve having an upstream seat () with the seat actuated by outside pressure (). Retraction members () continuously urge seat () to a retracted position out of sealing engagement with the ball. A sealing member () fits loosely within an annular recess in the seat ().