| 摘要 |
A binary balance seal assembly for use in a balanced pressure valve having a valve housing and a valve plug movable within the housing between an open position and a closed position. The seal assembly comprises an annular primary seal which is adapted to be retained within the valve housing. The primary seal is deformable into sealed engagement with the outer surface of the valve plug when pressure is applied to the primary seal as occurs upon the movement of the valve plug from its closed position toward its open position. In addition to the primary seal, the seal assembly includes an annular secondary seal which is adapted to be retained within the valve plug itself. The secondary seal is movable into sealed engagement with a portion of the valve housing when the valve plug is moved to its closed position so as to prevent upstream pressure from causing fluid to leak downstream of the valve plug.
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