What exactly are the flow characteristics of butterfly valves?
Thread Content
https://www.renrendoc.com/paper/115794737.html For this article, the largest fluctuations in flow rate occur between 0~45°, that is, when the valve is open to 50% of its full opening. However, the flow characteristic curve of butterfly valves is what we refer to as approximately equal percentage; it can be seen from the curve that the flow change is small at low opening degrees, while it is large at high opening degrees. This contradicts that article as well (meaning that at an opening angle of 45°, the flow rate is already very high; increasing the opening angle further results in only a small change in flow rate, which is more characteristic of a quick-opening valve). May I ask where the problem lies, or if there is a misunderstanding? Additionally, if a butterfly valve is used for regulation within a 90° opening range, what opening degree is optimal?
https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=1533479 There are similar questions under this post; after seeing this image, there’s now a contradiction
I talked with the Conval software team, and the general idea is as follows. The flow characteristics of butterfly valves include equal percentage and linear types; from these, equal percentage correction and linear correction are derived. It is related to the change in pressure difference of the valve in the pipeline. Theory is theory, and practice is practice. The actual flow characteristics, as the diameter increases, become more linear and deviate toward a quick-open characteristic.