Detecting leaks in pressurised pipes by means of transients

Reliable and quick techniques are needed to locate and estimate leaks in pressurised pipe systems in order to reduce water loss as much as possible. The aim of the present paper is to show that the use of unsteady-state tests, which give rise to small overpressure, can be considered as an appropriate method. During these tests, it is necessary to record the pressure-time history - the 'pressure signal' - in just one section of the pipe, the 'measurement section'. On the basis of a thorough laboratory investigation, the influence on the pressure signal of size and shape of small leaks, along with discharge conditions and initial flow regime, is analysed. Some remarks about the possible applicability of the obtained results to pipes of different material can be found. A reliable criterion is provided for a first-approximation estimation of leak size, based on the results of an inverse method procedure concerning pressure signals.