Abstract: A check valve includes a tubular sleeve bounding a longitudinally-extending flow-through passage for fluids, a disc having a first material affixed along a first portion of its periphery to a flexible hinge member, and a bill affixed at a first end to one or more of the sleeve, the flexible hinge member, and the disc. The check valve also includes one or more of the following of (i), (ii), and (iii): (i) at least one groove, rib, insert, or combination thereof that extends longitudinally along a length of the disc, the bill, or both the disc and the bill; (ii) at least one groove, notch, rib, insert, or combination thereof that extends laterally along a width of the bill; and (iii) at least one ripple that extends longitudinally along a length of the bill and, optionally, longitudinally along a length of the disc.

Abstract: A check valve includes a tubular sleeve bounding a longitudinally-extending flow-through passage for fluids, a disc having a first material affixed along a first portion of its periphery to a flexible hinge member, and a bill affixed at a first end to one or more of the sleeve, the flexible hinge member, and the disc. The check valve also includes one or more of the following of (i), (ii), and (iii): (i) at least one groove, rib, insert, or combination thereof that extends longitudinally along a length of the disc, the bill, or both the disc and the bill; (ii) at least one groove, notch, rib, insert, or combination thereof that extends laterally along a width of the bill; and (iii) at least one ripple that extends longitudinally along a length of the bill and, optionally, longitudinally along a length of the disc.

Abstract: An air diffuser system contains a manifold and a plurality of elastomeric "duckbilled" check valves. The manifold is constructed from a conduit material and can be arranged in many different configurations. The valves are made from an elastomeric material, such as rubber, preventing the valves from being clogged with sludge, sediment, or other debris commonly found in waste treatment water. Additionally, the valves can be bored with predetermined orifice sizes, allowing the volume and pressure of escaping air to be determined prior to installation. To make installation of the valves easier, various types of coupling devices may be used to attach the valves to the manifold. Examples of coupling devices include restrictive orifices, "Y"-shaped conduits, and nipple conduits. Multiple valves can also be fabricated on a common cuff prior to installation.

Abstract: An asymmetrical check valve has an inlet end, a transition part and an outlet end, with a pair of vertical lips facing one another. The lips may be flat or they may be curvilinear. The check valve is asymmetric about a horizontal longitudinal plane through the check valve. The bottoms of the transition part and outlet end may be aligned, with a major portion of the lips extending above the horizontal plane. It is thus possible to install conventional or wide bill check valves in installations with little or no clearance between the outlet end and ground level.

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.