How should we understand some concepts related to control valves?

The last edit to this post was made by chensf123 on 2012-4-17 at 17:18. The standard GBT4213-2008 \"Pneumatic Control Valves\" makes it clear that the maximum difference between the forward and reverse strokes measured under the same input signal is what constitutes the hysteresis. The basic error at the lower limit (starting point) of the signal is the starting-point deviation ； The basic error at the upper limit (endpoint) of the signal is the endpoint deviation. Rated stroke deviation: By applying a 120% signal to the actuator’s air chamber, the ratio of the additional stroke covered by the valve stem from 100% to 120% signal to the rated stroke is the rated stroke deviation. Dead zone: Slowly change the input signal (increase or decrease) until a noticeable change in displacement is observed, thereby obtaining a corresponding input signal value ； Slowly change the input signal in the opposite direction (decrease or increase) until a noticeable change in stroke is observed, resulting in another input signal value ； The absolute value of the difference between the above two inputs is the dead zone.