| 摘要 |
PROBLEM TO BE SOLVED: To reduce a required amount of gas for pressurization with a simple structure and without operation failure by changing pressure in a closed chamber with a pressurization means and a pressure-reducing means being connected to the closed chamber being surrounded by first and second gate valves for varying the thickness of a door being formed by both the gate valves. SOLUTION: First and second gate valves 71 and 72 are lowered to a position facing transfer ports 51 and 52 via a cylinder rod 61a, a valve 131 is opened, and a specific atmosphere gas is sent into a closed chamber 101 from a compressor 121 via a pressure resistant hose. The inside of the closed chamber 101 is pressurized, the gate valves 71 and 72 are opened left and right, the thickness of a door being formed is increased, an O ring 81 being mounted onto the outer bottom surface of the first gate valve 71 is allowed to adhere to the circumferential part of the transfer port 51, at the same time, an O ring 82 being mounted on the outer bottom surface of the second gate valve 72 is allowed to adhere to the circumferential part of the transfer port 52, and the transfer ports 51 and 52 are closed. Then, a valve 132 is opened, a vacuum pump 122 is actuated, an exhaust gas in the closed chamber 101 is evacuated for reducing pressure, the gate valves 71 and 72 are narrowed toward a center for rising via a cylinder rod 61a.
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