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.

An apparatus can include a housing, a plunger configured to reciprocate along an axis within the housing, and an internal fluid chamber disposed in the housing. A valve, having a valve base and a deformable seal, can also be included in the apparatus. The apparatus can further include a seat having an aperture therein. The valve is configured to move into and out of contact with the seat when the plunger reciprocates within the housing, based upon a fluid pressure in the internal flow chamber. In addition, an outer diameter of the deformable seal of the valve is less than an outer diameter of the seat.

A rotary union including a housing, a piston, and a shaft is provided. The piston has a first fluid passage therethrough and is configured to slide axially between a first position and a second position. The shaft has a second fluid passage therethrough and is configured to rotate. A first port is arranged in the housing and is in fluid communication with a cavity formed between the housing and the piston. The first port is configured to deliver a pressurized fluid into the cavity to actuate the piston from the first position to the second position. A chamber is formed in the housing and surrounds an interface between the first and second fluid passages. A second port arranged in the housing is in fluid communication with the chamber. The second port is configured to apply a vacuum to the chamber to evacuate fluid leaked into the chamber from the interface.