Valve positioner surging

It is usually due to air leakage, especially minor leaks that are not detectable at all. If the valve is kept in a position with a very low opening degree, flow control is more precise; in such cases, even minor leakage from the actuator can easily cause fluctuations in the valve position, which in turn leads to fluctuations in flow rate and results in instability in production. . . . .

Dear sea friends, I have also encountered similar situations in my actual maintenance work. Apart from replacing the locator, are there any other solutions?

This post was last edited by changshu2008 on 2016-12-26 at 14:03. Surging in valve positioners can be caused by various factors: The first possibility is that the air chamber of the actuator is too small, and the sensitivity of the positioner is too high, resulting in surging. Due to the change in signal, the output pressure of the locator **exceeds the required pressure, causing the locator to revert to its original position** ； The feedback exhaust immediately reduces the pressure or brings it back to zero, resulting in continuous output and feedback cycles. Solution: Replace the positioner feedback spring, and add a throttle valve at the output from the positioner to the actuator in order to control the gas flow rate. The second possibility is that the feedback rod is not fixed, and there are moving parts in motion. Solution: Secure the feedback rod and tighten the connectors. The third possibility is air leakage in the actuator and air chamber. Solution: Replace the seal or the air chamber diaphragm. The fourth possibility is air leakage in the positioner amplifier. Solution: Replace the amplifier, or replace the seals. The fifth possibility is that there is debris in the locator nozzle, causing poor control of air release. Solution: Clean the nozzle and remove foreign objects. The above information pertains to the possible causes of surging in mechanical valve positioners and the methods for troubleshooting it. Regarding the causes of surge in intelligent valve positioners, there is one possibility, and then there are issues with the initialization settings. You can refer to the relevant manufacturer’s instruction manual to handle it!