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The industry switches to maintenance-free NRVs

07 February 2016

Around a third of UK Water Companies are now changing over from specifying traditional cast iron flap check valves to a tried and tested non-return valve (NRV) that solves many of the issues with the old counterweight and lever design.

The faster closing Surgebuster version

The new resilient hinge check valves (RHCVs) employ a flexible reinforced disk that works more like a heart valve, as it has no hinge, with a soft seal closure. They are guaranteed for 25 years and offer the major benefit of remaining clog-free even in heavy rag raw sewage applications, while also saving energy as the pressure needed to lift the valve flap is reduced (the Coefficient of friction being less than half of that of the old design).

But if they are so effective, and already tried and tested why haven’t they been used in the UK before? The simple answer, says valve specialist MGA Controls, is that it has taken a long time to gain WIMES specification, British Standard accreditation and acceptance on many of the Framework contracts. David Wilson, managing director of MGA and the person responsible for bringing the product to the UK market takes up the story:

“Gaining approvals and working with key specifiers to prove that these products deliver a significant saving in reduced maintenance costs and energy saving has taken time. Like anything new, people need time to get used to it. We are, however, now replacing a large number of cast iron valves that have been the same for decades with this new design of NRV.

"Several of the UK Water Companies have also run trials over the last three to four years and are now automatically replacing their standard weight and lever check valves with the Val-matic SwingFlex RHCV or the faster closing Surgebuster version.

“Our task now is to reach the other water companies and related stakeholders - framework contractors, consultants, planning teams, plant designers and maintenance engineers - to let them know the product is here and offers substantial benefits over the outgoing design.

“The water companies who are already on-board and have deployed the Val-matic valves now have first hand experience that the product claims are justified. We have over a hundred case studies from users where the valves were fitted in trouble spots and where the old-style valves were getting blocked-up every few months, requiring a team to service the valve at substantial costs.”

MGA has been able to record the cost savings from several locations and compile the data into a white paper, which is freely available to download from the company's website. The reduced costs, especially when spread over the 25 year guaranteed life-span, add up to huge figures when compared with the purchase costs. Not only that but key performance targets from equipment availability figures and overall maintenance costs can be substantially improved upon.

How does it work?
The novel design of an RHCV means that it has no snagging points, an extremely low head-loss and is clog-free in both the vertical and horizontal orientation. The valve has a 45° seat; 35° stroke; a proven non-stick fusion bonded epoxy coating (internally and externally); and Buna-N or ethylene propylene diene monomer (EPDM) fully encapsulated, drop-tight discs that are ideal for handling hydrocarbons, and hydrogen sulphide, as well as clean water.

It therefore requires little or no maintenance in typical raw sewage or sludge handling applications and ensures considerable cost benefits throughout its lifecycle in the form of energy savings, lower valve replacement costs and a considerable reduction of long-term maintenance costs.

The cost benefit of switching to RHCVs for a moderately sized water company having say, 1,000 pumping stations (or 2,000 NRVs), could ammount to millions of pounds per year and possibly in the tens of millions over the lifetime of the valve - if they were all changed over. These savings would obviously be even greater for water companies with a larger pumping station infrastructure.

According to a recently published document (‘How Resilient Hinge Check Valves could save the UK Water industry £millions’), this saving is broken down to 25 year cost savings based on reduced maintenance costs through not needing to regularly ‘de-rag’ and ‘de-clog’ the valve; further savings due to zero replacement costs (backed up with a 25-year warranty on moving parts), and further energy savings due to lower head-loss and consequent lower pump running costs.

The other operational benefits of an RHCV are not to be underestimated either. The Val-Matic Swing-Flex NRV will not only reduce clogging, it can eliminate slamming, protect the pumps from damage and can be mounted in a vertical orientation without compromising performance. It will therefore contribute to reduced pump maintenance and re-pumping costs. The valve complies with British Standards and WIMES regulations, is available in a range of sizes and is available now in the UK.

UK Water Companies certainly seem to be convinced, with successful deployments in multiple extreme applications across several hundred sites by Yorkshire Water, Northumbrian Water, Thames Water and Wessex Water amongst others. David Wilson again:

“The cost savings that can be achieved through replacing weight and lever check valves with a high quality RHCV really are quite considerable. Whilst there may be a small incremental cost at the time of purchase, this cost is often easily absorbed within the first months of deployment due to greatly reduced de-ragging and zero maintenance.”

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