| 摘要 |
A shutoff valve assembly which includes a valve body comprising a first and second flanged sections disposed on opposite sides of a main flow chamber; a disc seat disposed within the valve body a shutoff disc having a diameter substantially the same as the outer diameter of the disc seat; a disc shaft perpendicularly disposed within a sidewall of the valve body and mechanically affixed to the shutoff disc at a recessed portion of the inner surface of the valve body such that the disc does not restrict fluid flow, provide turbulence or cause a pressure drop while in the open position, the disc shaft having an inner end disposed within the valve body and an outer end disposed external of the valve body, the inner end being a terminal end and the outer end being sealed by means of a packing gland which prevents leakage of fluid from the shutoff valve; a positive spring actuator assembly comprising a lever attached to the disc shaft, a spring connected to the lever which is capable of rotating the disc shaft about its axis, and a fail safe fusible link connected to the lever means in such a manner that the disc is in an open position during normal operations and closed when the fusible link is severed due to increased external temperatures or mechanically released; and an external bypass valve capable of directing the fluid flow from one side of the disc to the opposite side when the disc is in the closed position.
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