Abstract: The present invention is directed to an inversion-resistant tide gate valve comprising a generally tubular sleeve bounding a longitudinally-extending flow-through passage for fluids, the sleeve having an upstream fluid inlet end region adapted to be affixed to an effluent conduit and a downstream fluid outlet region, the downstream fluid outlet region of the sleeve being integrally formed with a longitudinally-extending trough, where the trough is formed of an integral bottom wall and an integral pair of side walls. A disc is affixed along a first portion of its periphery with a flexible member to the downstream fluid outlet region of the sleeve, and a second portion of the periphery of the disc opposite the first portion rests within the trough on the bottom wall of the trough.

Abstract: An inversion-resistant check valve or tide gate valve has a sleeve bounding a longitudinally extending, flow-through passage for fluids. The sleeve has an intermediate region and an upstream fluid inlet end region mountable on a discharge end of a conduit which is elongated along a longitudinal first axis of symmetry. The sleeve also has a downstream fluid outlet end region comprised of two or more thin and flexible lips which are opposed to each other and which are pre-formed to define a bill which is curvilinear. The lips are thinner and more flexible than the intermediate region. The curvilinear bill ensures sealing of the thinner, more flexible lips, allows easier opening of the valve, and reduces the likelihood of gapping in the lips. Unwanted backflow through the check valve is thereby prevented.