| 摘要 |
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 between the seat members, which cavity extends substantially the entire length of the seat members; and passageway means for carrying fluid under superatmospheric pressure from a source external to said frame, through the interior chamber of said blade, and into the enclosed cavity that is formed by the first and second seat members when the blade is in the valve closed position.
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