Under normal circumstances, which is better for the flow characteristic of a level control valve: linear or equal percentage?

It depends on your manufacturing process; it’s not necessarily the best approach. Based on personal experience, 90% of the time it’s better to use equal percentages. I also hope that those who truly understand can offer some guidance!

Selection of the flow characteristic for control valves: The options provided below are preliminary; for detailed choices, refer to the specialized documentation: (1) Choose a logarithmic characteristic when S > 0.6. (2) Choose logarithmic characteristic for operation at low opening degrees and when the unbalanced force varies greatly. (3) Choose a linear function when the required response speed of the adjusted parameter is fast, and a logarithmic function when it is slow. (4) The pressure regulation system can have a linear characteristic. (5) The level control system can have a linear characteristic. 1) Application range of linear flow characteristic: ① Small differential pressure changes, almost constant ； ② The changes in the main parameters of the process flow are linear ； ③ Most of the system pressure loss is incurred at the control valve (when its opening is changed, the differential pressure across the valve changes relatively little) ； ④ External interference is low, changes in the set value are small, and a narrow adjustment range is required. 2) Applicable range of equal percentage characteristic: ① Large actual adjustable range ； ② As the opening degree changes, the differential pressure across the valve changes significantly ； ③ The pipeline system has high pressure losses ； ④ Significant fluctuations in the load of the process system ； ⑤ Control valves often operate at low opening degrees.

It is only possible to determine whether to use linear characteristics or equal% characteristics by considering your process conditions; linear characteristics are generally used when equal% characteristics are not sufficient.

Generally, it is better to choose a linear flow characteristic for controlling the liquid level

Learned it! Third floor! It is best to take one’s own circumstances into account, balancing cost-effectiveness with the importance of device control

Experience shows that valves with a linear flow characteristic are preferable for level control.

Selection of the flow characteristic for the control valve in a level control system: When the pressure drop ΔP across the control valve is one of the following values, a linear characteristic represents the best choice. 1. Constant ⊿P ； 2. △P decreases as the load increases; △P at the maximum load is greater than △P at the minimum load, which is 20% ； 3. △P decreases as the load increases; △P at maximum load

1: Normal ΔP/Maximum ΔP > 0.75 – Linear: 1: Level constant control; 2: Flow control system where the main disturbance is the set value. Proportional: 1: Flow, pressure, and temperature control systems; 2: Pressure control system where the main disturbance is the set value. 2: Normal ΔP/Maximum ΔP ≤ 0.75 – Proportional: Various control systems