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There is a question like this: When calibrating a control valve equipped with an electric valve positioner, what signal should be input for calibration? When calibrating a control valve equipped with a pneumatic valve positioner, what signal is used for calibration? Please share your thoughts. Bonus points
Electric input signal, pneumatic input air signal.
For the calibration of control valves equipped with electric valve positioners, input signals of 4 mA, 8 mA, 12 mA, 16 mA, and 20 mA are generally used, with calibration carried out at these 5 points. Calibration of the valve with air supply: Connect the air source and adjust the setpoint so that the output is 20 kPa; check whether the valve’s stroke is at the starting position (the maximum stroke position). Adjust the setpoint output to 100 kPa and observe whether the valve stroke reaches its maximum (starting position). Select 5 pressure values of 20 kPa, 40 kPa, 60 kPa, 80 kPa, and 100 kPa for the input signal to perform calibration. The corresponding valve position indications should be 0%, 25%, 50%, 75%, 100%.
Electric: 4–20 mA; Pneumatic: 20–100 kPa for calibration
For pneumatic types, it depends on the spring range to decide
Does electricity power electric systems, and is air pressure used in pneumatic systems?
A 4-20ma signal is sufficient for calibration; it works the same for electric and pneumatic systems. However, there are also pneumatic valves with air signal regulation, such as the Fisher 3660 regulator