| 摘要 |
A mechanism for opening or closing a shut-off valve, the mechanism having a valve actuator for moving the valve from a first position to a second position, an urging means, a trigger which, when activated, triggers operation of the valve actuator, the trigger including a retainer which ordinarily holds the shut-off valve in the first position against the force applied by urging means, and a sensor reactive to an external stimulus which releases the trigger upon receiving appropriate external stimulus.
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