Drives&Controls & BACK TO BASICS n SPONSORED BY The hidden problem that costs water companies millions Pressure transients cost the UK’s water sector millions of pounds every year. Nick Brown, managing director of Erskinebased Electronic Drives & Controls (EDC), explains how drives can be used to reduce pipe bursts significantly across the water network. Pipe bursts are a perennial problem for the UK water industry. Every year we see the same cycle of cold weather followed by burst pipes and leaks, inevitably resulting in angry customers and negative headlines. It can cost upwards of £2,000 to detect and repair a single leak, and with many utilities suffering thousands of bursts every year, it’s an expensive and disruptive problem. Often these bursts are treated as isolated events, yet many have the same underlying cause – pressure transients. When pumps use DOL (direct on line) starting, they create sharp surges in pressure on the discharge side, while suction pressure drops sharply at the same time. This results in the phenomenon known as pressure transients – also known as water hammer. In practice it means that you might have 16 bar or more of pressure travelling at the speed of sound down pipes designed to carry a fraction of that. The transient doesn’t dissipate, even over several kilometres of pipe. It carries on all the way down the pipe, looking for the weakest point. And if it can’t find a tap or an outlet somewhere, you end up with a burst. Transients are difficult to measure. Normal methods such as telemetry won’t detect them. With one customer, we deployed hundreds of special high-speed transient pressure loggers which were able to capture hundreds of pressure readings per second. It was only then that the true scale of the problem became clear. Using a drive instead of DOL flattens the pressure curve by gradually ramping up the pump motor, and keeps it at a more reasonable level – within 0.5 bar of the desired network requirement – instantly removing the problem. As well as reducing bursts by more than 75%, pumping at a lower pressure also saves energy, and extends the life of the pipes. As an ABB Value Provider for Scotland and North East England, our purpose is not just to install and service drives. We’re here to find and solve the customer’s problems by providing local knowledge and engineering expertise, backed up by market-leading drive technology. When we find a persistent problem, we try to go deeper, working with the customer to find the underlying causes, and develop permanent solutions. For more information visit www.edcscotland.co.uk, or search for “ABB Value Provider”.
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