A spring return check valve that has a body forming a fluid flow path therethrough, a cover that closes an opening in the body and including a cavity therein facing the fluid flow path, a disc that rotates from a first position closing the fluid flow path and a second position fully opening the fluid flow path and a spring connected between the cover and the disc and including extensions integrally extending from each end of the spring to cause the spring to buckle into the cavity when the disc rotates to the second position.

A pressure relief assembly (100) includes a housing (102) including an air passage chamber (104) having a flap barrier (122) surrounding at least one airflow passage. A membrane flap is secured within the air passage chamber. The membrane flap covers the airflow passage(s) in a closed position. A portion of the membrane flap is configured to move off the airflow passage(s) into an open position. A noise-dampening seal (120) formed of a noise-dampening material is proximate to at least a portion of the flap barrier. The noise-dampening seal is configured to reduce noise generated by movement of the membrane flap as the membrane flap moves from the open position to the closed position. The noise-dampening seal provides a sealing interface with the membrane flap in the closed position.

A return air blocking device for ventilation of the interior of a motor vehicle, with a frame or housing with at least one sealing surface and with at least one flexible valve flap mounted on the frame or the housing, which in an idle position abuts on the sealing surface and prevents a flow of air through the return air blocking device, and which, when a sufficient pressure occurs, assumes an opening position lifted from the sealing surface in which it allows a flow of air through the return air blocking device, wherein the at least one valve flap comprises at least one slit on its end mounted on the frame or housing, wherein the frame or the housing comprises at least one holding projection which engages in the at least one slit.

A spring return check valve that has a body forming a fluid flow path therethrough, a cover that closes an opening in the body and including a cavity therein facing the fluid flow path, a disc that rotates from a first position closing the fluid flow path and a second position fully opening the fluid flow path and a spring connected between the cover and the disc and including extensions integrally extending from each end of the spring to cause the spring to buckle into the cavity when the disc rotates to the second position.

An insert is provided for insertion through an opening in the surface of a conduit, the insert comprising an insert body having first and second open ends defining an axis of flow therebetween. The insert further comprises a valve flap connected to the insert body. The valve flap is moveable between a closed position in which it creates a closure, thereby preventing flow along said axis, and an open position in which the valve flap allows flow along the axis. The valve flap is arranged so that, when in the open position, it is substantially U-shaped in side cross-section and is oriented with respect to the insert body so that said U-shape arches over the axis of flow.

Provided is a duct damper comprising: a hollow housing provided inside the duct so as to enable ventilation; a blocking plate provided in the housing and opening and closing the hollow; a fastener detachably fixing the blocking plate to the housing; and shape maintaining members respectively provided on the sides of the blocking plate so as to respectively maintain half of the shape formed by the blocking plate. According to the present invention, even if both sides of the blocking plate are bent with a center bar as an axis, since the shape maintaining members half and half support the both sides of the blocking plate, respectively, so as to maintain the shape, vibrations are not generated at either side of the blocking plate, thereby preventing noise.

A check valve with a a housing having an inlet connected to an outlet. A stop and a membrane are disposed in the housing. The membrane is movable and bendable to control fluid flow between the inlet and the outlet. The stop may be an elongated extension about which the membrane may bend along a line or a curve such that the extension lies between overlapping sections of the membrane.

A check valve with a a housing having an inlet connected to an outlet. A stop and a membrane are disposed in the housing. The membrane is movable and bendable to control fluid flow between the inlet and the outlet. The stop may be an elongated extension about which the membrane may bend along a line or a curve such that the extension lies between overlapping sections of the membrane.

A ventilation flow rate regulator for a pressurised tank of a vehicle. The regulator includes a body including a gas inlet and a gas outlet, and at least one restrictor mounted movably relative to the body. The restrictor is mounted to reduce a cross-section of at least one path of a gas flow proceeding from the inlet to the outlet, when a flow rate at the inlet is greater than a predetermined threshold. The regulator is arranged so that the cross-section remains non-zero irrespective of a flow rate.

The present disclosure is directed to a backwater valve assembly comprising a main valve body, a flapper sub-assembly, and a cap. The main valve body has an inner wall that can define a recess into which the flapper sub-assembly can be removably secured. The flapper sub-assembly includes at least one flapper element that can pivot between an open position, in which the flapper element allows fluid to flow through the backwater valve assembly, and a closed position, in which the flapper element prevents fluid from flowing in the opposite direction. The flapper sub-assembly can be removably coupled to the cap to allow the flapper sub-assembly and cap to be installed in or removed from the main valve body together as a unitary assembly.