Detecting leaks in plastic pipes

Water utilities commonly use acoustic equipment to locate leaks. Although acoustic equipment is generally considered satisfactory for metallic pipes, its application to plastic pipes could be problematic. This study found that leaks in plastic pipes could be located using acoustic techniques; however, there were several difficulties. Professional leak detection teams using leak noise correlators rarely succeeded in locating leaks because the frequency range selected automatically by correlators (or manually by operators) was usually too high. The frequency content of leak signals from plastic pipes was mostly below 50 Hz. Listening devices were ineffective unless they were used very close to leaks. Acoustic leak detection methods can be made more effective by revising the automatic-mode algorithms of correlators, using finely turnable noise filters, and measuring leak signals with hydrophones or highly sensitive vibration sensors. Nonacoustic methods such as radar, thermography, and tracer gases, appear promising.