| 摘要 |
PROBLEM TO BE SOLVED: To facilitate operation of forced opening of a valve and cancel thereof. SOLUTION: A cylindrical holder 8 surrounding a control rod is provided on a top part of a valve casing, and a push pin 11 for pressing the control rod and a energization member for energizing the push pin 11 in the pressure releasing direction of the control rod are provided in the holder 8. A pressure retaining window 12 and a pressure-releasing window 13 which correspond to a pressure retaining position and a pressure releasing position of the control rod by the push pin 11, respectively, are provided through the side wall of the holder 8, and an engagement means 21 which can freely engage to and disengage from each window from inside of the holder 8 is provided on the push pin 11. A reset means 14, which cancels an engagement status between the engagement means and the pressure retaining window 12 is provided on the outside of the holder 8. A valve is thereby forcedly opened with a one touch operation by pressing the push pin 11 and a forced opening of valve is canceled with a simple operation by the reset means 14.
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