Check valves promise long-term stability in chemical processing
10 January 2012
The prevention of failure-free backflow of media has, traditionally, presented a challenge for check valves in chemical processing applications. The valves are subject to wear because of the mechanical and chemical stresses.
A new generation of check valves, from GF Piping Systems, part of the Georg Fischer group, are said to eliminate this problem. Development of the valves focused on how wear and tear of the moving parts of the valves could be minimised, which led to the development of a redesign design of the valve interior.
Two years before coming to market, GF Piping Systems offered the new check valves, in a variety of versions, to a customer in the chemical process industry for field testing in the effluent neutralisation process. The company had, previously, approached Georg Fischer because it wanted a solution which would reduce the amount of wear to its check valves. Check valves, in particular, are subject to many wear factors including mechanical stress because of high flow velocities, water hammer in the pipeline and chemical attack on the valve components, such as elastomer seals. This can have serious consequences on process control – beginning with a small leak, caused by swelling of the elastomer seal to valve components becoming jammed and finally total breakdown of the valve.
These experiences were incorporated into the development of the valve which was hydrodynamically optimised, to minimise pressure loss and at the same time increase flow by 25% compared to the previous generation.
Another effect of the new cone contour is that the valve can optionally be equipped with a return spring and thus implemented in new applications. Equipped with a return spring, the check valve can be installed in nearly any position, horizontal or vertical.
The elastomer seals also contribute to reliability of the valve and an optimised the seal profile is said to guarantee leak-tightness. The profile of the cone surface that comes into contact with the sealing ring is spherical making it completely leakproof if there is a slight deflection of the cone, ultimately protecting the pump from backflow of the process medium.
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