Conversion between valve equivalent length Le and local resistance coefficient
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I’m having trouble with the calculation of pipeline pressure drop, as it involves various types of valves, including ball valves and butterfly valves. I have a question: regarding ball valves, the manufacturers provide a resistance coefficient of 0.01–0.02. However, according to the standards for pipeline pressure drop, the equivalent length Le for ball valves is 30D. If we use the following formula to compare these values, will they match? If we calculate ζ using the formula ζ=λLe/D, then ζ=0.023*30=0.69 (under the current flow conditions, λ=0.023; the calculation process is not repeated here). The calculated value differs significantly from the reference value provided by the manufacturers. I’m not sure what the issue is; please advise!
Suitable for calculations in the process section; it helps you transfer them there. More people are welcome to join the discussion @HaiChuanXiaoDangJia @*lihuagong @*nht1
hf=λ*Le/D*U^2/2 hf=ζ*U^2/2 Obviously, ζ=λLe/D. Based on computational experience, if λ=0.023, the flow is likely in the drag-square region, and the calculations are correct. Then it is necessary to consider whether the reference values provided by the manufacturer correspond to the flow conditions during calculation. In my opinion, whether it is the manufacturer’s reference value or a calculated value, the difference in actual piping systems is not significant, as there aren’t too many valves
:Handshake. Thank you for the reminder; I hadn’t considered whether the drag coefficient provided by the manufacturer matched the flow regime used in the calculations. I’m very grateful, and I will check with the manufacturer later.