Sound advice 
Canada-based Echologics says that its proprietary acoustic technologies can find leaks in all types of pipe – including those made from PVC. 

The company measure time-of-flight of the sound of a leak using acoustic sensors and a correlation function. The sensors can be placed on a fire hydrant or in specific places on a pipe, for instance – and can accurately measure exactly where a leak occurs by determining the time taken for the sound of the leak to reach two different sensors.

The sound it measure travels through the pipe itself – rather than the liquid it is transporting – which means that 
Developing a system that could work in PVC pipes was a challenge, because plastic has far higher attenuation and dampening than metal. Also, some old metal systems have been repaired with sections of plastic pipe. 

Recently, Echologics helped a UK company to identify a leak on a 3in PVC pipe. The LeakFinder- ST correlator identified the precise location of the leak by bracketing it over 420ft (128m). Field technicians accurately correlated the location, which was confirmed by ground-sounding over the main. An excavation team was dispatched to fix the leak – which had a flow rate of 3.5gpm (0.8 m3/hr).