Abstract: The disclosure is directed to a high performance butterfly control valve which may be applied and utilized in critical high pressure and/or high performance operation environments. In accordance with the invention, the vane of the butterfly valve is formed to include first and second diametrically opposed, asymmetrical projections, each extending from the periphery of the vane and each including a plurality of fluid control passages formed therethrough. The projection adjacent the downstream rotated periphery of the vane is formed to a generally smooth, streamlined configuration to minimize the overall volume of the vane, and to facilitate a smooth, turbulence free flow when the valve is in the full open position. Moreover, the projection adjacent the upstream rotated periphery of the vane is formed to a length of extension which is greater than the length of extension of the diametrically opposed projection.

Abstract: An air damper having a plurality of blades of the opposed blade type is provided wherein such damper provides substantially uniform air flow distribution throughout the flow area of such damper.

Abstract: A valve assembly having a frame with a fluid flow opening therethrough; at least one blade mounted in the frame opening to be movable from a valve open position, in which fluid is able to flow through the frame opening, to a valve closed position, in which fluid is blocked from flowing through said frame opening, said blade having opposing upstream and downstream surfaces, an interior chamber lying between said surfaces, and edge portions joining said surfaces together; a first seat member carried by at least one of said edge portions; a second seat member carried either by an interior wall of the frame or by the edge portion of an adjacent blade; said first and second seat members being so constructed and arranged that when the blade is in the valve closed position the seat members seat against one another to block the flow of fluid around the blade; said first and second seat members being formed such that when the seat members are seated against one another the seat members define an enclosed cavity betwee