Abstract: A valve includes a housing having a first opening and a second opening, a single flapper disposed in the housing about a point of rotation between the first opening and the second opening wherein the flapper is rotatable between the first opening and the second opening to seal one of the first opening and the second opening, the flapper having one of a first seal or a first seal land disposed on each of a first side and a second side thereof, and a second seal or a second seal land disposed about the first opening and the second opening, the second seal or the second seal land of the first opening and the second opening cooperating with the one of the first seal or the first seal land disposed on each of a first side and a second side of the flapper to seal the first opening and the second opening wherein the first and second land and/or the first or second seal is tapered towards or away from the point of rotation.

Abstract: A valve for use in an aircraft that includes a cabin that requires conditioned air and avionics that may require conditioned air. The valve includes a housing, a single flapper disposed in the housing, a first opening in the housing in proximity to the flapper for carrying conditioned air to the avionics, a second opening in the housing in proximity to the flapper for carrying conditioned air to the cabin, an electromechanical device for moving the flapper from a first position in which air may be vented to the first opening and not the second opening and a second position where air may be ducted to the second opening and not the first opening.