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Technology Development
PPIC is the exclusive North American licensee of the Sahara system.
Sahara was developed in the United Kingdom by the Water Research Center (WRc). WRc developed correlators, the most commonly used technique for the identification of leaks, in the early 1970's.
Of all the 'passive' forms of leak detection, correlators have been the most effective.
They have helped to significantly reduce water leakage in many areas, especially within smaller diameter
distribution networks. However, they were found to have the following limitations:
- Multiple leaks within a given monitored area often yield an unlocalizable signal.
- Leak signal strength dissipates rapidly within large diameter pipelines - pipelines over 12” (300mm) in diameter - inferring that the acoustic signal of the leak may not be practically detectable by correlators in large diameter pipe.
- Multiple diameter mains may lead to inaccurate identification of leak location.
- The leak signal is lost within pipelines that contain air pockets.
- Non-metallic mains (HDPE, PVC, asbestos cement or concrete) do not conduct the leak signal effectively. The leak noise is attenuated very rapidly as it travels away from the source in these types of pipe, inferring that correlators may have difficulty in practically identifying leaks in non-metallic mains.
- At any significant distance from the leak point background noise can corrupt the leak noise signal.
As a result, the use of correlators carries a risk, common to all forms of passive leak detection, that a leak-free survey may incorrectly classify a line as leak-free.
WRc recognized these limitations and investigated alternative methods of leak location in
large diameter water transmission mains. After careful investigation, WRc concluded that the most
reliable method of detecting leaks, and pinpointing their position accurately, would be to pass a
sensor through the pipe and determine the point where the leak noise signal was at maximum amplitude.
This development work formed the basis of the system that is currently used under the name “Sahara”.
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