A backflow prevention apparatus is provided with a check valve and a float-type backflow prevention valve, these being installed in this order as one proceeds from upstream to downstream. The check valve comprises a valve seat; a valve member that closes the valve at the valve seat due to an upwardly directed restoring force; and a restoring force exerting member that exerts an upwardly directed restoring force on the valve member. The float-type backflow prevention valve comprises an annular valve seat; a float that rises in accompaniment to a rise in a water level of wastewater to close the valve at the annular valve seat; a guide member that guides movement of the float in a vertical direction; and a constraining member that constrains a lowermost position to which the float can move.

Various embodiments of a device for regulating a fluid flow are described that can include first and second downwardly-sloping valves that are biased in a closed position to prevent odors from escaping the device. The device can also include first and second downwardly-sloping valve seats, and configured such that an end portion of the first valve can be seated beneath the first valve seat and an end portion of the second valve can be seated beneath the second valve seat when the first and second valves are in a closed position, respectively.

A drain valve has a housing defining a drain conduit for the passage of fluids to be drained, the drain conduit having a first rim defining an inlet to the drain conduit opposite a second rim defining an outlet from the drain conduit. One or more non-return valves are within the drain conduit between the first rim and the second rim and have a closed configuration and an open configuration adapted to allow fluids to flow through the outlet of the drain conduit. A vent conduit extends within the drain conduit and comprises internally a lower valve seat, an upper valve seat and a bypass valve positioned between the lower valve seat and the upper valve seat. The bypass valve is adapted to allow gas to bypass the one or more non-return valves and escape to atmosphere when the gas reaches a predetermined pressure.

A drain valve has a housing defining a drain conduit for the passage of fluids to be drained, the drain conduit having a first rim defining an inlet to the drain conduit opposite a second rim defining an outlet from the drain conduit. One or more non-return valves are within the drain conduit between the first rim and the second rim and have a closed configuration and an open configuration adapted to allow fluids to flow through the outlet of the drain conduit. A vent conduit extends within the drain conduit and comprises internally a lower valve seat, an upper valve seat and a bypass valve positioned between the lower valve seat and the upper valve seat. The bypass valve is adapted to allow gas to bypass the one or more non-return valves and escape to atmosphere when the gas reaches a predetermined pressure.

A waterless trap for use in a drain assembly includes flow enhancing features to promote the vortex water flow of water received in the trap, an improved sealing arrangement to enhance the seal between a seal member and the housing to inhibit sewer gas leaks from an attached drain pipe by maintaining an evaporation barrier that assists in retaining water in a corresponding p-trap, and a plurality of air passages can allow the trap seal to open with ease when the drain pipe is pressurized. These features may be used in combination with one another or may be independently employed.

A waterless trap for use in a drain assembly includes flow enhancing features to promote the vortex water flow of water received in the trap, an improved sealing arrangement to enhance the seal between a seal member and the housing to inhibit sewer gas leaks from an attached drain pipe by maintaining an evaporation barrier that assists in retaining water in a corresponding p-trap, and a plurality of air passages can allow the trap seal to open with ease when the drain pipe is pressurized. These features may be used in combination with one another or may be independently employed.

A non-return device (10) for use with a waste trap is described. The non-return device comprises a sealing portion (12) having first and second sheet members (14, 16), a device inlet (18), a device outlet (20) and a transition portion (22) providing fluid communication between the device inlet and the sealing portion. The transition portion has a convex section of wall (24).

A non-return device (10) for use with a waste trap is described. The non-return device comprises a sealing portion (12) having first and second sheet members (14, 16), a device inlet (18), a device outlet (20) and a transition portion (22) providing fluid communication between the device inlet and the sealing portion. The transition portion has a convex section of wall (24).

A drain valve device includes a drain valve housing arranged to be located within a drain opening. The housing has a wall structure surrounding an axis so as to define an internal flow passage through the housing and a strut member depending radially inwardly from the wall structure. The device has one or more valve members. A gas vent passage may be provided in the housing and a vent valve or control member may be provided to selectively prevent flow through the gas vent passage.

A drain valve device includes a drain valve housing arranged to be located within a drain opening. The housing has a wall structure surrounding an axis so as to define an internal flow passage through the housing and a strut member depending radially inwardly from the wall structure. The device has one or more valve members. A gas vent passage may be provided in the housing and a vent valve or control member may be provided to selectively prevent flow through the gas vent passage.