The control valve operates very slowly at speeds above 75%. Why?
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There is a control valve on site, equipped with a Siemens intelligent positioner. The valve sends signals well when at below 75% opening; however, when it is above 75%, the valve first reaches 75% and then gradually moves to the valve position corresponding to the signal sent. Why is this?
Has the locator been adjusted properly? It’s just that the spring of the scale has low elasticity, resulting in a slight delay in response
First check the air supply pressure, and then look at the problem with the locator
It would be best to have a photo of the valve as a whole; it’s not necessarily a problem with the positioner
Check the air source pressure and flow rate, and see if the pipe size is too small.
It’s probably the pressure release valve. Processing procedure: If there was no such problem before but it appears now—check the air pressure in the locator, whether the air lines are blocked, the lubrication of the push rod, and the locator itself. As before, simply enlarge the trachea, reduce the number of springs, add pneumatic amplifiers, etc