| 摘要 |
PURPOSE:To detect many points efficiently by connecting plural probes and pulsers to a pair of measuring circuits, driving respective pulses successively at a fixed time interval, and synchronously with the driving, connecting respective probes to the measuring circuits successively. CONSTITUTION:When a controller 9 switches both a multiplexer 8 and a circuit 7 to the 1st channel simultaneously and sends a driving signal after very short period (a), a pulser 31 is driven, an ultrasonic wave is radiated from a probe 11 and a pulse wave voltages corresponding to T, S and B echoes are generated and amplified to measure the time between the echoes T and S by a circuit 5 and the time between the echoes S and B by a circuit. After the passage of time tau, the 2nd-n-th channels are successively switched. The time interval tauis expressed by the equation I when the maximum distance between the probe and the periphery of a pipe is dmax and the maximum thickness of the pipe is tmax. Provided that a sound speed in a solution is VL, a sound speed in the pipe body is VS and a constant fixed by the measuring circuits is alpha. Consequently, the number of measuring circuits can be reduced and the pitting corrosion of a pipe line having a large diameter can be detected with a small pitch. |
