| 摘要 |
PURPOSE: To attain a high speed response characteristic by which a trace of impurity can be measured in a short time by measuring a transiently changing trace of gas concentration. CONSTITUTION: A substitutive characteristic when CH4 gas remaining in T-shaped piping 17 of a dead space part is substituted with H2 gas by various purge methods is evaluated. First of all, valves 7, 9 and 11 are opened, and after CH4 gas of 1kgf/cm<2> is introduced to the piping 17, the valves are closed, a next, valves 2, 5, 6, 4 and 13 are opened, and N gas is introduced to an atmospheric pressure mass spectrometer 15. An N2 gas flow rate at this time is set in 1L/min by a mass flow controller 16. Similarly, CH4 is introduced to the piping 17, and after a batch purge, N2 gas is flowed, and is introduced to the mass spectrometer 15, and the CH4 gas concentration is measured. A batch purge of one time is performed in such a way that the valves 7, 9 and 12 are opened, and after pressure of the piping 17 is reduced for five seconds, the valve 9 is closed, and the valves 2, 8 and 10 are opened, and N2 is filled, and the valves are closed. Therefore, concentration change can be detected in a short time. |
