Air admittance vent

摘要

The air admittance vent (AAV) includes a cup shaped vent body and a vertically reciprocating valve element that seats against a valve seat that has two separate contact areas defined by an annular ridge and a conical face formed in the bottom of the vent body. When the valve element moves into its closed position, the pliable diaphragm of the valve element initially contacts the annular ridge, which forms a first part of the valve seat before moving fully into sealing contact with the conical face, which forms the second part of the valve seat. The contact with the annular ridge provides a first initial seal before the diaphragm nests into contact with the conical face to form a second seal with the valve seat.