Patent ID: 6904929

Claim:
A normally open check valve for passing gas in a first direction, from an upstream side of the valve to a downstream side of the valve, and for passing gas in a reverse direction to the first direction, and for preventing liquid flow in the first direction, comprising: a) a body member having a chamber with at least one side wall, an upstream and a downstream opening, the side wall including a tubular side wall portion having a diameter narrowing to at least a contact diameter as the chamber side wall extends upstream; b) a bell shaped member with a portion of the member received within the tubular chamber and having a mouth, a closed base, and a flexible wall extending between the mouth and the base that includes an annular portion of diameter greater than the contact diameter of the chamber side wall and greater than the perimeter of the mouth, wherein the specific gravity of the bell shaped member volume as defined by the mouth opening, the base and the wall therebetween is less than one, and the mouth is disposed within the tubular chamber portion facing upstream and the base is generally downstream of the mouth; and c) a retaining member affixed to the bell shaped member base, extending generally downstream from the bell shaped member base, and adapted to engage the chamber side wall downstream of the contact diameter; whereby the retaining member arrests movement of the bell shaped member when gas flows past the bell shaped member, and when liquid flows in the first direction past the mouth of the bell shaped member, the bell shaped member wall peripherally contacts the contact diameter of the chamber to thereby stop the flow of liquid past the bell shaped member.