| 摘要 |
PURPOSE:To prevent underground water from penetrating a device and to pass only detection gas by shielding detecting elements of a gas detector with a protection cover. CONSTITUTION:When the detecting device 1 is buried underground, the gap between a waterproof cap 11 and a base part 2 is narrow, so neither earth nor sand enters the device 1 even if earth and sand and rainwater flows. Further, the protection cover 3 and metallic netting 8 prevent the earth and sand from entering the device 1 and the waterproof filter 9 prevents water from entering the device, so that element E1 and E2 are protected without being damaged by earth and sand or water. Further, only air A or detection gas G is passed. Then, if the device 1 is dipped in the underground water 15, the space part is set properly between a cap 11 when fitted to the device 1 and a filter 9 fitted inside the cap is set properly so that the maximum capacity of the space part is maximum at a burying position b=2m, and the underwater level reaches the ground surface 14a, thereby preventing the underground water 15 from entering filter 9. Then, when the underground water 15a falls below the burying position of the device 1, the device 1 begins to detect the gas again.
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