| 摘要 |
PROBLEM TO BE SOLVED: To perform measurement reduce in error by rapidly stabilizing an indication value after the changeover of a flow channel passing through an NO2/NO converter and a flow channel not passing therethrough. SOLUTION: When a pump 32 is operated, measuring gas is sucked from a measuring gas inlet 2 and sucked toward a reaction tank 16 while dust in the gas is removed by a filter 4, and moisture in the gas is removed by a duhumidifier 6. The measuring gas is guided to a reaction tank 14 through a converter 8 when a flow channel changeover device 10 is connected to a flow channel 9a, and guided thereto through a resistance pipe 38 without being passed through the converter 8 when the flow channel changeover device 10 is connected to a flow channel 9b. At this time, though the flow channel changeover device 10 is connected to either one of the flow channels 9a, 9b, the measuring gas passed through the converter 8 is sucked to a branched flow channel 9d. By this constitution, the measuring gas always flows through the converter 8. The measuring gas sucked to the branched flow channel 9d is guided to an ozone generator 24 through an activated carbon column 22.
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