Patent ID: 7270146

Claim:
A one-way air admittance valve assembly for venting ambient air into a system while preventing the escape of gases within the system, comprising: a housing having first and second passageways in fluid communication one to another and a valve seat defining an opening demarking said first and second passageways; a cap sealingly engaged or engageable with an upper end of said housing defining an upper portion of said first passageway and being positioned above said valve seat; a flat generally thin, flexible, resilient sealing membrane positioned atop said valve seat for sealing thereof by gravity only; said sealing membrane being sized to freely slidably fit within the upright side wall of said housing which, in combination with said cap, defines said upper portion of said first passageway wherein an uninterrupted sealing area located centrally on said sealing membrane remains in alignment over said valve seat as said sealing membrane is moved freely by air flowing within said upper portion of said first passageway; whereby ambient air in said second passageway freely flows into said first passageway and the system through said opening when air pressure in the system is less than atmospheric pressure; said sealing member including spaced apertures formed therethrough positioned between the sealing area and a periphery of said sealing member for enhancing system airflow into said upper portion of said first passageway to seal said sealing member against said valve seat to prevent escape of air from within the system when air pressure within the system is above atmospheric pressure.