Patent ID: 8567434

Claim:
An air admittance valve to be connected to a sanitary waste pipe system for admitting atmospheric air into the waste pipe system towards a valve sealing means in response to a sudden pressure reduction in the systems in order to protect the water traps in the system and to prevent discharge of contaminated air from the system to the atmosphere, the air admittance valve including a valve housing having: a vertical tubular member adapted to be connected to the sanitary waste pipe system and having a first inner space; a cover or cap at an upper end of the valve housing and having a second inner space; a valve opening having a periphery and a valve seat provided with a soft annular seat at the periphery of the valve opening, situated between the tubular member and the cover, said valve seat being adapted to co-operate with a movable closing member having an upper surface and a lower surface; at least one passageway leading from a third inner space of the housing towards the surrounding atmosphere; at least another passageway leading from the second inner space within the housing towards the first inner space of the waste water pipe system; said at least one and at least another passageways being respectively in contact with either the upper surface or the lower surface of the movable closing member so as to lift said movable closing member upon a sudden loss of air pressure in the sanitary waste pipe system allowing fresh air to enter into the system via the at least one passageway in order to balance the air pressure inside the sanitary waste pipe system, wherein the movable closing member comprises a rigid movable member having the shape of a circular poppet valve provided with an inverted bowl shaped inner part, and wherein the movable closing member is further provided with a conical peripheral collar having an inverse angled conical surface extending upwards.