| 摘要 |
An automatic safety shut-off system for installation in a gas line or other fluid line which automatically shuts off the flow of fluid in response to an emergency situation. The system is characterized by three valves, each responsive to a different emergency situation. The first valve includes a sealing piston which is controlled by a pressure responsive locking mechanism which responds to above normal gas line pressure. The second valve responds to lower than normal pressure downstream of the shut-off system. The third valve responds to the interruption of electrical power supplied to machinery using fluid from the gas line. The pressure responsive locking mechanism of the first valve includes two locking toggle joints movable between a locked and an unlocked position. When in the locked position, the toggle joints retain the sealing piston in the open position, thereby allowing fluid flow through the valve. When in the unlocked position, the toggle joints allow the sealing piston to close, thereby interrupting fluid flow through the valve. A pressure responsive locking piston is linked to the toggle pins of the toggle joints and is movable between a locked position, locking the toggle joints, and an unlocked position, unlocking the toggle joints, whereby above normal fluid pressure in the valve chamber of the first valve causes movement of the locking piston from the locked position to the unlocked position.
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