Seek solutions to difficult problems with pneumatic control valves
Thread Content
The medium flowing through this pneumatic control valve is air. In recent months, the valve’s opening degree has been fluctuating frequently in the early hours of the morning; even when a specific opening degree is set manually, it still fluctuates up and down. Additionally, when trying to increase the opening degree manually, the valve moves slowly and does not reach the desired position, while the process of reducing the opening degree proceeds smoothly. I hope someone can help analyze the reasons for this
It’s the limit issue; take it apart to check the limit
The limit rod is fine; the valve stem does move, and the DCS communication issue has also been checked and found to be okay
Check whether fluctuations in pipeline pressure are causing variations in the valve’s opening degree. If there are no fluctuations in pipeline pressure, then check the air supply pressure; this valve is of the air-actuated type, so verify whether there are any issues with the air supply pressure
The air pressure is set at four kilograms; the medium flowing in the pipes is air, and its pressure remains stable as well. Our company’s maintenance staff have checked it and found no issues, which is why we’re reaching out to everyone for their insights. And how did you tell that this valve is a air-operated valve? When the air is lost, does it close the valve or remain in place?
Check the membrane head seal; try using a different locator
It could be caused by a change in temperature. Check for leaks in the gas line.
If it is a pneumatic control valve, check the diaphragm head to see if the diaphragm in it is damaged
Are the problems still occurring at fixed times? Early in the morning? Is it normal at other times?
This post was last edited by Thirty-two points on 2020-10-14 at 13:23. If problems occur when the signal is stable, it’s most likely that the actuator is faulty. Based on your description (the valve doesn’t open fully), the signal no longer corresponds to the actual opening degree of the valve. Try adjusting the actuator again to see if this resolves the issue; if not, you’ll need to contact Samson for help. Furthermore, if conditions permit, check whether the valve can move through its full stroke smoothly.