WET News

Specifiers file: JANUARY 2017 WET NEWS 15 Pressure reducing valves are needed to control flow but their flexible diaphragm can suffer fatigue. Oxford Flow believes it has the answer. Taking the pressure off T he flow of water in distribution networks is regulated in many instances by pressure reducing valves (PRVs). These valves automatically control flow in order to maintain a precise outlet pressure which protects the downstream network and equipment from leaks, bursts and damage. Traditional PRVs modulate flow to control pressure using a flexible diaphragm made from elastomers such as Nitrile rubber. However, the very elasticity that allows these elastomers to do their job and constantly flex, also leaves them prone to embrittlement and fatigue over time. This means that traditional diaphragm PRVs require THE CONCEPT • The IP series PRV works flawlessly with standard pilots and smarter network technology to suit every application • The Oxford Flow range of PRVs use a piston rather than a diaphragm, thus require very limited maintenance and dramatically decrease the cost of ownership • The IP Series PRV has been extensively tested by many of the UK's biggest water networks and is undergoing field trials in the UK and Europe • Smaller and significantly lighter than its competitors the Oxford Flow PRV is significantly more eco-friendly and sustainable than its peers NEED TO KNOW 1 The IP Series is significantly lighter than its competitors. This low weight means that the unit is far easier – and crucially, cheaper – to install, potentially reducing the crew required for installation and removing the need for heavy lifting equipment while removing/reducing the risk of handling injury 2 The IP Series is manufac- tured using approved potable water polymers, which eliminate corrosion – a further mode of failure in traditional PRVs 3 The acetyl resin polymer construction is cavitation resistant and rated to 16 bar g 4 The IP Series PRV minimum head loss performance offers a significant improvement over class leading competitors across a range of flows. The typical head loss is just 0.2 bar g. 5 With just one moving part and no diaphragm to maintain the robust and reliable design offers maintenance schedules of up to15 years – dramatically reducing the cost of ownership. THE VERDICT "The valves we've been using are extremely heavy, making installation tricky and expensive. We've looked for a solution to this issue for a long time, and Oxford Flow's PRV may just be it. It's made of plastic, and much, much lighter than all other comparable devices. This makes installation much easier, and greatly reduces our labour costs. We intend to replace all of our current PRVs with the Oxford model in the future – it simply makes sense, commercially and practically" James Carr, European operations manager, Veolia Mobile Water Services (Veolia Water Technologies UK has worked with Oxford flow.to develop and deploy a more mobile and accurate solution for hydrant pressure reducing valve (PRV) assemblies) Extensive testing has proven to be significantly more precise, efficient and robust frequent maintenance to avoid failure in service. Concept Oxford Flow's IP Series PRVs represent a leap forward in valve design. Engineered in Oxford University's famous Osney Thermo-Fluids laboratory, the Oxford Flow method of pressure regulation utilises a piston- sensed mechanism in place of a diaphragm. This concept came about when Professor Thomas Povey, an engineering professor at the university, was conducting experiments into heat transfer in jet engines. He found that even the very best pressure control valves on the market were unable to provide the levels of performance his experiments required, so set about creating a new kind of pressure regulation himself. The PRV that Prof Povey has created differs from conventional regulators in that instead of using a diaphragm, it uses a patented balanced sensing piston. One side of the piston is exposed to downstream pipeline pressure while the other side is balanced against a pressure cavity controlled by a pilot regulator. During operation, the piston moves inward, reducing the size of the cavity when the downstream pipeline pressure exceeds that within the pressure cavity set by the pilot regulator to maintain precise, stable control across the entire operating range. Downstream pressure The movement of the piston actuator in closing reduces the flow rate to maintain a stable downstream pressure. When demand increases, the downstream pressure falls below that set by the pilot and the reverse operation occurs, the cavity expands as the pilot feeds it, opening the flow path, which increases flow and maintains a stable downstream pressure. The result is a regulator that extensive testing has proven to be significantly more precise, efficient and robust than its competitors. The industrial applications of this new PRV were quickly realised, and it has now been commercialised by Oxford Flow. The company is a technology spin-out from the University of Oxford, and is backed by Oxford Sciences Innovation (OSI), a new £320M company created to support ambitious Oxford technology companies, funded by names such as Google and the Wellcome Trust. INSIGHT Pumps & valves Instead of using a diaphragm, the Oxford Flow method uses balanced sensing piston Prof Tom Povey and his compact, lightweight flow regulator Extensive testing has proven to be significantly more precise, efficient and robust

• Cover