| 摘要 |
A fluid shut-off device is provided which comprises a magnetic valve body provided in a non-magnetic hollow casing for movement between a first position to open a fluid passage and a second position on a valve seat to close the passage, and an annular permanent magnet provided outside the casing and urged toward the periphery of the valve seat by an elastic spring. The valve body is normally held in the first position but is allowed to move to the second position by the magnetic force of the permanent magnet at a predetermined condition.
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