From: Andy Soos, ENN
Published August 9, 2012 07:43 AM

Leaky Pipes

Leaky pipes are a common problem. Where is it leaking so that it can be found and fixed. With longer pipes especially those which are buried, this is a a major problem. Developing more accurate ways of finding leaks would enable water companies and consumers to save revenue and reduce their environmental impact. The system invented at the University of Sheffield tests pipes by transmitting a pressure wave along them that sends back a signal if it passes any unexpected features, such as a leak or a crack in the pipe’s surface. The pressure wave is generated by a valve fitted to an ordinary water hydrant, which is opened and closed rapidly. The wave sends back a reflection, or a signal, if it encounters any anomalous features in the pipe. The strength of that signal can then be analyzed to determine the location and the size of the leak.

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The concept was originally developed by a team led by Professor Stephen Beck in the University’s Department of Mechanical Engineering, the invention was developed into a prototype device in partnership with colleagues in the Department of Civil and Structural Engineering, and Yorkshire Water.

Between 20 and 40 per cent of our total water supply can be lost through damaged pipes. What makes the new test particularly useful is that it can be done in the field.

The device has now been trialled at Yorkshire Water’s field operators training site in Bradford and results show that it offers a reliable and accurate method of leak testing. Leaks in cast iron pipes were located accurately to within one meter, while leaks in plastic pipes were located even more precisely, to within 20 centimeters. The results of the trial are published in a paper entitled, "On site leak location in a pipe network by cepstrum analysis of pressure transients", in the Journal - American Water Works Association.

Existing leak detection techniques rely on acoustic sensing with microphones commonly used to identify noise generated by pressurized water escaping from the pipe. This method, however, is time consuming and prone to errors: the use of plastic pipes, for example, means that the sound can fall away quickly, making detection very difficult.

In contrast the device invented by the Sheffield team uses a series of calculations based on the size of the pipe, the speed of the pressure wave, and the distance it has to travel. The device can be calibrated to get the most accurate results and all the data is analyzed on site, delivering immediate results that can be prioritized for action.

Dr James Shucksmith, in the Department of Civil and Structural Engineering at the University of Sheffield, who led the trial, said: "The system has delivered some very promising results at Yorkshire Water. We hope now to find an industrial partner to develop the device to the point where it can be manufactured commercially."

Dr Allyson Seth, Networks Analytics Manager at Yorkshire Water commented: “Driving down leakage on our 31,000 km network of water pipes is a high priority for us. "Over the last 12 months alone, we’ve targeted leakage reduction and as a result we’re currently recording our lowest ever levels of leakage."

For additional information see Leaky Pipes.

Pipe image via Wikipedia.

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