| 摘要 |
PROBLEM TO BE SOLVED: To provide an operation method of an evacuation device capable of slow exhaust without arranging an apparatus device for the slow exhaust. SOLUTION: A main valve 13 having a large diameter and a pressure gauge 19 are installed in an exhaust pipe 12 for connecting a vacuum chamber 10 and a main pump 11. A check valve 31 is installed in an exhaust line 15 of the main pump 11. An auxiliary pump 14 is arranged in parallel to the check valve 31. A pump having an exhaust speed of 10% of the main pump 11 is used for the auxiliary pump 14. A valve having a spherical valve element floatable in a valve body, opening the valve by floating by pressure higher than atmospheric pressure, and closing the valve by being seated on a lower valve seat by dead weight in pressure lower than the atmospheric pressure is used as the check valve 31. In exhaust from the atmospheric pressure of the vacuum chamber 10, the slow exhaust is performed by starting only the auxiliary pump 14, and the main pump 11 is started after reaching a prescribed degree of vacuum.
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