The flow coefficient or flow curve of general-purpose valves
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I checked many samples; for some common valves, the samples only provided connection parameters, without giving the flow coefficient or the flow-pressure curve. Why is this? Is there no manufacturer to conduct the tests? Could any senior member share the curves for the L41H series? Thank you!
For general-purpose valves, which are used for opening/closing purposes, the resistance coefficient K is given for the fully open condition; this is also the case in the manufacturer’s tests. As for control valves, which are used for precise flow control, a lot of money is spent on experiments to determine the flow capacity Cv at opening degrees of 10–100%. To determine this value, one can use the formula Cv=30 x d2 / SQRT (K) for when the valve is fully open. For example, for a globe valve with a K value of 8–9 and an inner diameter of 1 inch, the Cv value is approximately 10 when the valve is fully open.