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 damping valve includes a valve seat member having a port and a first valve seat surrounding the port, a main valve body seated on or unseated from the first valve seat, the main valve body having a second valve seat oppositely to the valve seat member, a subsidiary valve body seated on or unseated from the second valve seat, a valve-body intermediate chamber provided between the main valve body and the subsidiary valve body in an inner circumferential side of the second valve seat, a restrictive passage that causes the port and the valve-body intermediate chamber to communicate with each other, the restrictive passage being configured to apply resistance to a flow of fluid passing therethrough, and a subsidiary valve body biasing means configured to bias the subsidiary valve body toward the main valve body.

A thermostatic valve, which includes a main body portion, a cavity formed as part of a main body portion, and an inner wall integrally formed with the main body portion adjacent the cavity. A circumferential flange is integrally formed with the inner wall, such that the circumferential flange surrounds a valve cavity. A valve member is attached to the inner wall disposed in the valve cavity, and a flow aperture is formed as part of the inner wall. Fluid flows through the flow aperture into the valve cavity, and when the pressure in the valve cavity is above a predetermined value, the valve member contacts the inner wall, preventing fluid from flowing through the flow aperture.

A flow limiting device with a back flow prevention mechanism includes a body that has an isolation board and a water-through cavity. The isolation board has a water-through hole connecting to the water-through cavity and a flow limiting device having a flow limiting component and stop ribs which limit the position change of the flow limiting component. The stop ribs are arranged on the inner wall of the water-through cavity at equal intervals. The flow limiting component is set in the water-through cavity. The outer side of the flow limiting component is contacted on the stop ribs. A back flow prevention mechanism comprises, a back flow prevention component which is fixed in the water-through hole and a supporting structure which is set for supporting the back flow prevention component when it expands on the inner wall of the water-through cavity.

An emergency degassing apparatus is provided, comprising a base body, an emergency degassing valve having an emergency degassing opening and a pressure cap for closing the emergency degassing opening, and a pressure compensation element (DAE) having a first and a second pressure compensation valve.

A valve body structure of a valve device comprises a sealing surface, and a venting surface defining a ventilation relief opening through which air can flow from inside of the valve device to outside of the valve device. The valve body structure also comprises a number of retaining surfaces positioned between the sealing surface and the venting surface. The retaining surfaces cooperate together to (i) secure in place a rubber washer that allows air from inside of the valve device to flow around the rubber washer to outside of the valve device when air is flowing through the ventilation relief opening from inside of the valve device to outside of the valve device, and (ii) prevents debris from outside of the valve device from reaching the ventilation relief opening.