| 摘要 |
PROBLEM TO BE SOLVED: To easily confirm a full close state of a valve element by changing a liquid surface of colored liquid within a transparent display tube of an opening indicator installed at a remote location according to a change in volume within a cylinder chamber when a valve rod is advanced up to a front tip location in an axial line direction and the valve element is fully closed. SOLUTION: When a valve rod 2 is lowered up to a lower end location and a door body (valve element) is fully closed, volume of a cylinder chamber 12 is expanded. An oil surface of colored oil 13 stored within a transparent bottomed display tube 17 of an opening indicator 16 installed at a remote location and connected via the cylinder chamber 12 and piping 15 is lowered by expanding of volume of the cylinder chamber 12. Therefore, a full close state of the door body located at the remote location can be easily confirmed by visual observation of the oil surface of the opening indictor 16. When the valve rod 2 is raised up to an upper end location and the door body is fully closed, a door closing state can be confirmed since volume of the cylinder chamber 12 is reduced and the oil surface of colored oil 13 within the display tube 17 rises.
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