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As an accessory to pneumatic control valves, a valve positioner can determine the opening degree of the control valve, and it is used to convert electrical signals from the controller into air pressure. During transportation, various uncertainties can affect the accuracy of the locator; therefore, it is necessary to carry out inspections, adjustments, and cycle tests on the locator before using it. Valve positioner calibration sequence: (1) Adjust the input signal to 50%. Next, use the zeroing knob to set it at the 50% position of the specified stroke. (2) Determine whether the allowable value of the stroke is smaller or larger than the actual value, and adjust the stroke to the standard value through repeated season adjustments and stroke tweaks. The input signal is adjusted back and forth between 75% and 25% to confirm whether the specified position has been reached at 75% and 25%. If it is adjusted to the baseline value in this way, it will essentially become the baseline value within the range of 0~100%. (3) If the closing force of the valve is of significant importance, it is necessary to confirm that under reverse plug conditions, when the input signal is below the reference value, the value indicated by the pressure gauge at the output side drops to almost zero ； In the normal plug condition, when the input signal is above the reference value, the value shown on the pressure gauge at the output side essentially reaches the pressure of the air supply. When using a valve positioner, in environments with pressure-resistant and explosion-proof machinery, do not open the cover of the wiring box while it is powered on. During the power-on process, the main cover can also be removed for inspection and adjustment. Under such circumstances, be sure to take care to prevent sparks from being generated due to collisions during the operation. If it is necessary to open the junction box while it is powered on, it is essential to use devices such as gas detectors to thoroughly confirm that there are no explosive gases present.