Periodic fluctuations of the valve
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A level control valve fluctuates approximately every half hour. I was wondering if anyone knows what could be the reason for this? Pink for valve position, blue for liquid level
Automatic control of liquid level and valves, right? Under these circumstances, if you use automatic mode and the valve returns automatically after fluctuations occur, it has nothing to do with PID. Estimated reason 1: Could it be that the process conditions experienced a sudden large fluctuation within half an hour? ； 2. Check whether there is a problem with the valve AI output card ； 3. Is there a specific calculation method for configuration? Need to check the configuration ； 4. Check whether there are any problems with the valves on site, as well as the actuators
What is a material? The valve opening degree and liquid level changes are related; consider whether periodic variations in the fluid density are the cause.
Level control in any process flow simply means that disturbances occur
This post was last edited and supplemented by CHANGBAISHI on 2020-8-31 at 10:35. Check whether there are any leaks or blockages in the pressure gauge tubes; also see what happens if the positive and negative pressure gauge tubes are blown from the front or from the back. If the symptoms disappear in a short time, it may be related to a leak or blockage. Oh, it’s also necessary to observe the actual operation of the valves on-site to check for any sticking or discrepancies with what happens in the control room.
I recommend using two methods for inspection: 1. Switch the control valve to manual mode and set a fixed opening angle, then observe continuously to see if the issue persists； 2. Observe the actual operation of the valve on-site for a while longer, and check with the control room to ensure that the valve position output is consistent. Then identify the specific cause based on the actual situation.