| 摘要 |
PURPOSE:To detect the presence or absence and position of the leakage of an embedded conduit, by filling the conduit with gas containing no nitrogen or oxygen and subsequently sending said gas into the conduit from one end thereof at a constant flow speed while detecting nitrogen or oxygen due to leakage at the other end of the conduit. CONSTITUTION:Both sides of the city gas conduit 1 embedded in the ground are cut and one end of the part 1a to be detected is closed by a lid 3, and a nitrogen bomb 4 and a quantitative supply blower 5 are connected to said lid 3 while an exhaust pump 7, an oxygen gas detector 8 and a purge gas combustion burner 9 are connected to the lid 6 provided to the other end side of the conduit 1. The detection of leakage is performed as follows. That is, nitrogen gas is sent to the piping part 1a at first from the bomb 4 and purged city gas is burnt by a burner. Next, the piping part 1a to be detected is evacuated by the pump 7 to allow oxygen to flow in from a leak area and, subsequently, nitrogen is supplied to the piping 1a at a constant flow speed from the bomb 4 while oxygen arriving the detector 8 is detected and the time difference between at the supply time of nitrogen and at the detection time of oxygen is measured to detect the place and position of the leakage. |
