Abstract: A check valve for one-way flow of a fluid comprises a valve body defining at least two pairs of axially-extending sidewalls, each pair of sidewalls having a pair of resilient lips defining slit opening at the outlet end of the valve. In one embodiment of the invention, the valve body defines three pairs of sidewalls and corresponding lips which are arranged one another so as to provide the check valve with an “I-beam” cross-sectional shape. The I-beam check valve has a compact cross-section, making it suitable for mounting either inside or outside a pipe. The I-beam shape provides support along the valve axis so that the valve does not require any supplemental support structure. In another embodiment, the valve body may define two pairs of sidewalls having a “T-shaped” transverse cross section.

Abstract: A check valve for one-way flow of a fluid comprises a valve body defining at least two pairs of axially-extending sidewalls, each pair of sidewalls having a pair of resilient lips defining slit opening at the outlet end of the valve. In one embodiment of the invention, the valve body defines three pairs of sidewalls and corresponding lips which are arranged one another so as to provide the check valve with an “I-beam” cross-sectional shape. The I-beam check valve has a compact cross-section, making it suitable for mounting either inside or outside a pipe. The I-beam shape provides support along the valve axis so that the valve does not require any supplemental support structure. In another embodiment, the valve body may define two pairs of sidewalls having a “T-shaped” transverse cross section.