| 摘要 |
PURPOSE:To detect abnormal points of a pipe by driving an optical fiber unit, etc., into a pipe by compressed air from the end opposite to the end from which a steel ball, etc., is inserted by applying pressure, blowing out the optical fiber after the optical fiber insertion stops, and by measuring the length of the optical fiber unit, etc. CONSTITUTION:A steel ball 3 is blown into a plastic pipe 1 by air pressure 2. When there is an abnormal point 1a in the longitudinal direction of the pipe 1, the pipe is clogged with the steel ball 3 at that point 1a. Then, an optical fiber unit 4 is forced in by air-blown fiber method from the end opposite to the end from which the steel ball 3 is inserted. When the optical fiber unit 4 hits the steel ball 3 to stop, the air pressure 2 is applied from the reverse direction, i.e., from the end from which the steel ball 3 is inserted, to blow out the optical fiber unit 4. When the length of the blown-out optical fiber unit 4 is measured, it is possible to measure the distance l from the end to the abnormal point 1a where the steel ball 3 is held in the pipe. |
