Patent ID: 7311740

Claim:
An aircraft cabin air filtration system comprising: an inlet configured to receive a flow of air from an airflow source; an outlet configured to exhaust the flow of air to the aircraft cabin; an air filter positioned between the inlet and the outlet, the air filter being fluidly coupled to the inlet and the outlet and configured to filter the flow of air, whereby a differential pressure is developed between the inlet and the outlet; and a bypass valve positioned between the inlet and the outlet and in parallel with the air filter, the bypass valve being fluidly coupled to the inlet and the outlet and movable between an open position, in which the flow of air is bypassed around the filter, and the closed position, in which the flow of air is not bypassed around the filter, the bypass valve configured to move to the open position when the differential pressure magnitude reaches a predetermined opening value, the filter bypass valve including: a valve body having one or more flow channels extending therethrough, each flow channel having a cross sectional flow area, and one or more flappers rotationally mounted on the valve body and configured to substantially seal the flow channels when the bypass valve is in the closed position and unseal the flow channels when the bypass valve is in the open position, each flapper having a surface area, wherein the cross sectional flow area is less than about 50% of the surface area.