Leak Detection for Pipelines Using In-Pipe Optical Fiber Pressure Sensors and a Paired-IRF Technique

Leak detection is crucial in reducing water loss and improving the efficiency of water transmission in water distribution systems. A hydraulic transient paired-IRF (impulse response function) technique previously developed was demonstrated as an effective method for leak detection. However, the technique requires transient pressure measurements at two locations in close proximity in the pipe, which is often very difficult to achieve for buried pipelines using conventional flush-mounted pressure transducers. The current paper reports on the use of a customized in-pipe optical fiber sensor array for transient pressure measurement and the implementation of the paired-IRF technique for leak detection in a laboratory copper pipeline. The in-pipe optical fiber sensor array contains two fiber Bragg grating (FBG) pressure sensors contained in a protective cable. It is inserted into the laboratory pipeline through a tapping point to measure the pressure responses induced by a voice-coil pressure wave generator, which generates a persistent excitation. The paired-IRF technique is then applied to the measurements to obtain the paired-IRF of the pipe system. The paired-IRF is determined and clearly indicates the existence of the simulated leak (through a side discharge on the pipe). In addition, a pipe joint is detected using the paired-IRF trace, which confirms that the detection system and method have the ability to achieve high detectability. The successful experimental application illustrates that the in-pipe optical fiber sensor array can be applied in pipes with limited access points and leak detection can be achieved by combining with the paired-IRF technique.