The valve comprises a closing body in a valve chamber. The valve chamber is delimited on one end by an opposing wall and on the opposite end by a piston. The piston is pressed in the direction of the opposing wall by a press-on means. In this manner, the closing body is pressed against a centering seat axially aligned with the valve seat. The press-on means makes it possible that the valve will reliably close also in case of a small pressure differential between the valve inlet and the valve outlet.
