If there isn't enough flow to open a check valve fully, and keep it open, it will wear out long before it's time. In the case of a swing check, the disc will flap up and down in the fluid flow, like a flag in the wind. This is what causes them to wear out where the shaft connects to the disc. You can have the same problem with lift checks, or stop & check valves on boilers.
Check valves are like control valves - they need to be sized for the flow conditions. That usually makes them one pipe size smaller than the line they're installed in, if the line has been sized correctly. You can actually suffer a higher pressure drop from a partially open oversized valve than a smaller, properly sized one.
The effect of the actual velocity being less than the minimum required velocity for full disc lift is 'chattering' i.e partial opening and closing of the disc continuously thereby leading to the wear and damage of sealing surfaces. Hence, it absolutely essential to size the check valve properly. In addition, if there is pump in the line then the results are still worse. However, adequate care and caution need to be exercised in such installation to avoid problems.
Contact Durabla Fluid Technology at 1-800-206-4013. They are the original in-line silent check valve designer & have been making the check valve you need for many years. They will size the valve to your flow requirements
