The control valve has an open position but no flow; what happens when the open degree is adjusted and flow is restored?
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A system has 8 parallel pipelines, with one control valve for each pipeline. Today, it was found that the opening degrees of the control valves in all 8 pipelines ranged from 5% to 20%, yet no flow occurred in the pipelines; however, a pressure gauge on the main pipe indicated the presence of pressure. Then I moved the control valve and the flow rate returned to normal. What could be the reason for this? The medium is water, at a temperature of around 60 degrees. Thank you!
It might be that the regulated pressure at the outlet of each control valve is different.
The control valve has an opening range of 5%-20%; at such a low opening degree, the regulation effect is not satisfactory. The optimal range is 30%-80%. An opening degree of 5% is too low, resulting in a very small flow rate and inaccurate control. There may also be a dead zone in the valve, leading to inflexible operation. It is recommended to reduce the size of the valve or the valve seat in order to increase the opening degree.
The opening degree is too low, resulting in poor adjustment performance. The best results are achieved when the opening degree of the control valve is between 20% and 80%. For butterfly valves, the minimum opening degree should not be less than 15%; try using a smaller value
Control valves have an opening dead zone, and the ideal range should be between 30% and 80%
The opening is too small, the flow rate is too high, causing flashing and vaporization of the medium
What type of control valve is it? If ball valves or similar devices are used for regulation, a dead zone of 20% means that no flow occurs even at that opening degree, which is still considered normal
It is indeed possible for the opening degree of the control valve to be low; in addition, blockages caused by debris, high back pressure behind the control valve, or various signal interferences could also be the cause