Check valve

Abstract

A check valve in which a valve opens to allow a fluid to flow out when a differential pressure of a pressure in one area with respect to that in the other area becomes large and remains closed even when the pressure in the other area becomes higher than that in the one area includes a lip in contact with an opposed face provided at a position opposite to the check valve, wherein the lip is constructed so as to be in contact with the opposed face in such a way that the tip of the lip is bent to a side of the other area and a satin finish is given to the whole area of a surface of the lip that could be brought into contact with the opposed face.

Dependencies are inferred from the claim text.