| 摘要 |
PROBLEM TO BE SOLVED: To provide a safety valve capable of suppressing a leakage of a fusible plug due to creep and being used for a long time. SOLUTION: This safety valve 1 is provided with a main body 2, a piston 5 stored in the main body, a fusible alloy 7 filled between the piston 5 and the main body 2, and a spring 4 provided between the piston 5 and the main body 2. The piston 5 is provided with a passage 57 communicating with both ends, and both end parts are provided with a first pressure receiving face 561 and a second pressure receiving face 562. The piston 5 is a balance piston in which the pressure receiving faces 561, 562 have the same area and a pressure of gas in a tank acts in the reverse direction. As a result, gas pressure is not applied to the fusible alloy 7, an energizing force only due to the spring 4 acts, and a pressure applied on the fusible alloy 7 is maintained at substantially fixed pressure irrespective of a rise of gas pressure.
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