Using a geophone as an actuator to estimate the velocity of leak noise propagation in buried water pipes

Abstract

A common way to pinpoint a leak in a buried plastic water pipe is to use a leak noise correlator. This is performed by using the time delay between two measured signals and the velocity at which such signals travel along the pipe. In this paper, an investigation is carried out into the use of a geophone in reverse, driven by an oscillating voltage. It then acts as a tapping device, exciting the wave responsible for leak noise propagation, when it is attached to an access point to estimate leak noise velocity. Two different ways of exciting the geophone were investigated. Initial tests were conducted in the laboratory to determine the effectiveness of the device in generating a force over a wide frequency range. Field tests were then carried out on a buried pipe test rig and the predominantly fluid-borne wave was generated by the tapping device, that travelled at least 7 m.