Valve with hollow piston closure member - formed in two parts spaced by washer and axially movable by rotatable control sleeve

摘要

The valve has a fixed valve member around which fluid flows through pipes between which the valve is connected. A hollow piston is formed in two parts between which a washer is secured. The piston is slidable to and fro in annular chambers to seal against the valve member. Rings are secured to a control sleeve so that there is a helical groove between the rings in which washer is engaged. Rotation of the sleeve causes axial movement of the piston.