Regulating valve fluctuation issue
Thread Content
The control valve for on-site automatic control has its opening degree fluctuating between 30% and 40%, while the flow rate fluctuates between 60 and 80. However, the flow rate I need is 70. What is causing this outcome?
Adjust the PID parameters and see the effect
Operate the valve manually to check whether it still moves and whether there are any fluctuations in flow rate. If the valve is still fluctuating, check whether there is a booster; the sensitivity might be too high. If the valve does not fluctuate and the flow rate also does not fluctuate, it means the PID is over-adjusted; reduce the PID setting slightly
There are many possible reasons; conduct further checks to see if the air supply pressure is sufficient, whether the PID parameters need to be adjusted, if it’s a problem with the actuator, or if it’s related to the process itself (such as pressures before and after the valve not matching the design values, or insufficient spring force). In the case of intelligent actuators, high sensitivity and excessive friction in the valve can also lead to such issues
It might be due to improper adjustment of the PID parameters; also, check whether the process flow rate on site is stable, and whether the flow speed is too high, resulting in pulsating flow or something else
Manually set the opening degree and observe whether the valve remains stable. If it is stable, continue to monitor the flow rate; once the flow rate is stable, adjust the PID parameters. If it is not stable, inform the process team to make adjustments before proceeding with further tuning
Adjust manually until stable, then switch to automatic mode