On the selection of acoustic/vibration sensors for leak detection in plastic water pipes

Leaks from buried water distribution pipes are commonly located by applying the correlation technique to two measured acoustic/vibration signals on either side of a leak. The effectiveness of the correlation technique for locating leaks in plastic pipes depends on the type of sensors used and their sensitivities. Based on an analytical model of the cross-correlation of pressure responses established in an earlier study, this paper investigates the behaviour of the cross-correlation coefficient for leak signals measured using pressure, velocity and acceleration sensors. Theoretical predictions show that a measure of pressure responses using hydrophones is effective for measurements where there is a small signal-to-noise ratio (SNR), but a sharper peak correlation coefficient can be achieved if accelerometers are used. The theoretical work is validated to some extent with test data from actual water pipes on a test site in Canada