| 摘要 |
PURPOSE:To enable gas extraction operation safely and speedily by adding piping for gas extraction upon repair of gas piping parts to a gas piping system generating impure ions. CONSTITUTION:In a device comprizing a plurality of gas bottles 1 being connected parallely to an ion source 8 by means of a tap 2, pressure reducing valve 7, stop valve 5, needle valve 7 and air valve 6 and valves 3, 10, 11 for replacement of gas being provided on gas bottles respectively, the lines among the valves 3, 10, 11 are connected with gas extraction piping 12, whose one end is provided with a stop valve 13. When a needle valve 7 is clogged, the tap 2 is closed, while an air valve, stop valve 5, pressure reducing valve 4, gas replacing valve 3 and adjacent gas replacing valve 10 are opened, and thereby gas extraction is performed using adjacent piping. In this way gas leakage due to connection error of piping can be prevented and danger during replacement and installation of the piping and an excessive man power needed therefor can be eliminated.
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