A Novel Acoustic Sensor for Condition Assessment and Early Leak Detection in Water Pipes

Acoustic methods of condition monitoring of pressurized fluid-filled pipes are very popular but often fail to find the location and to estimate the severity of a small pipe wall defect or a leak. An accelerometer attached to the outside wall of a pipe or hydrophone inserted in the pipe is commonly used to detect a leak in a pressurized fluid-filled pipe or estimate the pipe condition from its acoustic response. In many cases these devices are not sufficiently sensitive for the purpose because of the complexity of the buried pipe network or high attenuation of acoustic waves in it. This work demonstrates that a new type of sensor that measures simultaneously the acoustic pressure and velocity in the acoustic wave propagated in a pipe can offer a considerable improvement in terms of sensitivity and accuracy of this condition assessment method. The performance of this sensor is evaluated through numerical simulation and tested in a laboratory on a 60 m long MDPE pipe loop to detect very small leaks that existing sensing methods would struggle to detect. This device is built of off-the-shelf components and can be adapted for delivery through existing pipe entry points. In the future it could be deployed on a robot to make the condition monitoring process fully autonomous and 10−50 mm accurate.