Experimental validation of a TDR-based system for measuring leak distances in buried metal pipes

In this paper, the experimental validation of a time domain re∞ectometry (TDR)-based method for pinpointing water leaks in underground metal pipes is presented. The method relies on sensing the local change in the dielectric characteristics of the medium surrounding the leak point. The experimental validation of the method was carried out through measurements performed on a pilot plant (experimental case P1) and through on-the-fleld measurements performed on two 'already-installed pipes', i.e., already operating and connected to the water distribution system (experimental cases P2 and P3). For the pilot plant, difierent leak conditions were imposed and the corresponding TDR responses were acquired and analyzed. For the on- the-fleld measurements, TDR measurements were performed on pipes for which a leak-detection crew had preliminarily individuated the possible presence of leaks (through traditional leak-detection methods). Finally, in view of the practical implementation of the proposed TDR- based leak-detection system, a data-processing procedure (which gives an automatic evaluation of the position of the leak) is also presented.