Issue link: https://onenorgren.uberflip.com/i/850945
Instead, a better valve The simplest approach is to attack this problem at its source – the valve. After all, it is the rapid closing of the valve that sends the fluid surging back upstream. But rapid closing is required for safe and effective operation in systems that typically use these 2-way valves. The question is, how can operators get the speed they need without creating a large water hammer effect? The answer is the IMI Norgren ® 82410 and the 82740 2-way normally closed valves. The beauty of this solution lies in the way these valves close. These IMI Norgren ® valves have a proprietary internal design that lets them close smoothly and gently, reducing pressure spikes while still maintaining closing speed. The result is valves that close in a quarter-second but with just a fraction (one-fifth) of the pressure surge typical of other similar valves. The proof System designers have been selecting these solenoid valves for years for their performance and robust design. They didn't always realize they were also getting the benefit of protection from the water hammer effect. But as this advantage became more apparent over time, IMI Precision Engineering decided to quantify the difference through comparative testing. The tests compared the IMI Norgren ® solenoid valve to three other best-selling valves. All were 2-way, normally closed, pilot operated valves with ½" NPT threads and ½" orifices and each closed in 250 ms or less. In other words, the valves were directly comparable. Each was tested on a pipe with inlet water pressure of 4 bar (87 psi), within the range of 70-100 psi typical of public waterline pressure. The power was shut off so the valves would move to the closed position and then the pressure upstream was measured every 100 milliseconds. Two competitors' valves hit peaks of 1440 psi, roughly 100 bar, and one hit 1101 psi or about 75 bar. Two of the three valves created not just one but two pressure spikes before the pressure returned to 87 psi. In contrast, the IMI Norgren ® 82410 reached a single peak of only 265 psi or 18 bar, less than 20% of the two valves with the highest spikes. The graph below tells the story quite clearly. 1600 1400 1200 1000 800 600 400 200 0 Pressure [psi] Time [ms] 0 30 600 900 1200 1450 1600 1725 1890 2000 2200 2500 2800 IMI Norgren anti-water hammer valve Competitor A Competitor B Competitor C Valve-by-valve comparison of water hammer pressure spikes 06 A white paper