Use of a zero-crossing matching algorithm for leak detection in buried water pipes

Water leakage from underground pipe networks has been a major concern due to the environmental damage and economic losses. Acoustic techniques based on cross-correlation are now in common use for water leak detection in many countries. This paper presents a zero-crossing matching (ZCM) algorithm for time delay estimation (TDE) to locate a leak from buried waterpipes. Theoretical analysis has been performed on simulated signals from which the time delay is further determined. It is found that the accuracy of the time delay estimateis affected by the selection of the window length and the maximum time lag. The ZCM algorithm is then applied to leak signal measurements made in an actualPVC water pipe and the effectiveness of the proposed TDE method is evaluated. In comparison with the conventional cross-correlationmethod, the algorithm has shown the advantage for ease of computation without loss of accuracy, which proves to be suited to this particular application.