| 摘要 |
A plurality of sampling tubes are connected with a selector valve and the selector valve selects one of the sampling tubes so that the sample gas is lead through the selected sampling tube and a pipe way downstream of the selector valve to a leakage detection system. The pipe way is provided with a gas flushing section for flushing with high pressure gas and the gas flushing operation is performed before each change-over of the selector valve. The flow of sucked gas is kept constant by providing a gas flow control device downstream of the leakage detection section. A pressure sensor is provided for the pipe way leading to the detection section, to detect the gas pressure in the pipe way and the output of the pressure sensor is used to detect an abnormality occurring in the detection section inclusive of the pipe way thereto and also to correct the output of the pressure detector in the detection section.
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