| 摘要 |
PURPOSE: Provided are a method and an apparatus for judging the terminal point of chemical cleaning by nitrogen-hydrogen analysis, which shorten cleaning time and prevent corrosion of facilities. CONSTITUTION: The method for judging the terminal point of chemical cleaning comprises the steps of: taking a vapor sample for the analysis; reducing pressure of the vapor to 1-10bar; condensing the vapor and cooling to 10-30deg.C; supplying the cooled sample regularly at 20-300cc/min; measuring the concentration of N2-H2 by using a selective N2-H2 gas permeable membrane and TCD; operating to output the concentration of the gas from a measured electrical signal; and outputting to show the operated result as letters or graphs. And the apparatus comprises a vapor sample taking pipe(1), a reducing valve(2) for controlling the pressure of the vapor sample, a cooler(3) for condensing and cooling the vapor sample, a device(4) for controlling the flow of the condensed sample, the TCD sensor(5) for measuring the N2-H2 gas, a device(6) for operating the gas concentration, and a device(7) for outputting the result of the operation.
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