New technology plugs leaking pipe problems
Water is increasingly regarded as a precious resource, yet more than three billion litres are typically lost each day as a result of leaking pipes.
Water companies invest considerable time and resources trying to combat this persistent problem. Now new technology, developed using research conducted at Loughborough is helping the industry win the war against leaking pipes. The View found out more from Professor Neil Dixon from the School of Civil and Building engineering.
The story begins in 2004 with a routine meeting between University academics and colleagues from the research team at Severn Trent Water (STW).
Understanding the characteristics of leaks and their frequency of signals they produce allowed us to better design the instrumentation to find them.
“At the meeting we discussed a range of issues of interest to them. One of the topics that came out strongly was the significant challenge faced detecting and locating leaks in pipes. They outlined that they use equipment called a correlator to detect leaks. These correlators, they said, work well on pipes made from steel and concrete but less well on plastic pipes which were being increasingly used as part of the programme of infrastructure improvement. We agreed to look at this for them,” explains Professor Dixon.
A small team was established. Professor Dixon’s background looking at acoustics in soil from failing slopes was directly relevant as was the acoustics, electronics and signal processing expertise of Dr James Flint, Head of the Communications Division in the University’s School of Electronic, Electrical and Systems Engineering.
A PhD student, who also had a background and interest in signal processing, was initially tasked with establishing the characteristics of noise typically generated by leaking plastic pipes. Extensive test pipe systems were established in the University laboratory and also outside where leaking buried pipes were tested so the team could understand and measure the noise generated from leaking pipes. Extensive testing also took place utilising the equipment and facilities at Lake House, STW’s training facility in Leicestershire.
“This was critical,” says Professor Dixon. “Understanding the characteristics of leaks and the frequency of signals they produce allowed us to better design the instrumentation to find them.” A working prototype was developed.
The PhD student then became a Research Associate and phase two of the project – a further three years - involved testing the systems in the field. It was vital to experience the practical problems faced on a day to day basis by operatives and examine how the modified system performed when compared with existing systems.
The work carried out demonstrated that the University system could detect leaks that the commercial system couldn’t and it located leaks more accurately. During this time the team optimised the specification of the improved system and detailed how it should be operated to obtain consistent results. This - the intellectual property of the system - was recorded and a patent established.
The lab and field trials convinced STW (who own the intellectual property) that they needed to identify a partner to help them commercialise the project. They chose Canadian company, Echologics who are
part of a much larger water distribution company in North America, Muller.
“They had in mind a number of ideas for improving their correlator but as the trials showed that the University test system was consistently better than their own version this convinced them to enter into discussions with STW,” comments Professor Dixon.
Via a licence agreement with STW, and over a period of two years, Echologics went on to build a number of correlators and undertake further testing, both in the UK with STW operatives and with their own operatives in North America. It out-performed all other correlator systems.
“The benefits of our modified system rapidly become clear – a vast reduction in the amount of time needed to find and fix leaks in plastic pipes and a considerable reduction in the number of false excavations being carried out. STW estimated that if the performance demonstrated in trials were replicated across all UK water companies, savings of approximately £5m per annum could be achieved,” Professor Dixon outlines.
Remarkably it was also established the system could be used to find leaks by locating the listening sensors on the ground where access to an actual pipe was not available. This is thought to be a first.
The product was fully launched to the market as the Leakfinder ST in May 2014. There have been orders from both the UK and internationally, particularly in Malaysia, and the University will share in the proceeds of commercialisation. The significance of the product was acknowledged earlier in the year at the UK’s Water Industry Achievement Awards, where it won Most Innovative New Technology of the Year Award and the overall Outstanding Innovation Award 2014.
Professor Dixon concludes: “At the start we had no real expectations about what might be achieved.. What we were able to do was optimise the system to detect, transmit and analyse the noise generated in a leaking pipe. We are delighted to have been at the forefront of developing this technology which has the ability to transform the capability of the water industry to respond to leaks in their infrastructure.”
What is a correlator and why are they important?
- A leak noise correlator is an instrument which listens to noise generated by water escaping from a leak at two remote locations.
- They are used to calculate where (in a buried pipe) the leak is located.
- Locating leak positions accurately reduces the number of excavations necessary to find and repair the leak which in turn means reduced costs of repairs and reduced loss of service.
How do correlators work?
- Sensors are placed at two locations on a pipe (typically at existing pipe access points such as stop cocks).
- Noise generated by the leak sends sound waves along the pipe (noise dissipates quickly in plastic pipes).
- Sensors pick up the sound waves, filter spurious noise and then calculate the velocity of the noise signal generated by the leak and travelling along the pipe.
- A wireless signal of the leak noise is then transmitted from the two sensors to a central processing computer which analyses the pipe material with the noise frequency of the leak, the time it takes to reach the sensors and to calculate the distance from the sensors to the leak.