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The electric valve positioner with double-acting pneumatic actuator features a piston design; the higher the pressure, the better the stability and control sensitivity of the valve. There is no need to limit the supply pressure; full-load supply pressure can be used to achieve a higher closing pressure. Its single-acting pneumatic actuators typically feature a diaphragm design, which allows them to withstand the full closing pressure while also reducing the load on the valve seat. A major issue with electrical valve positioners when the valve is closed is how to achieve full load on the valve seat to ensure a tight seal. The usual method is to calibrate the valve, not to verify whether the closing element is fully seated on the valve seat, but to ensure that the closing element is precisely positioned on the valve seat. To prevent corrosion of the sealing surface and maintain the designed leakage rate, an appropriate sealing load must be designed. Electrical valve positioners need to be calibrated when in use. The conventional calibration method involves using 5 points: 4mA, 12mA, 8mA, 20mA, and 16mA. At 12mA, the feedback rod of the positioner is in a horizontal position; for the other signal values, the valve should be at 0%, 100%, 75%, and 25% of its travel range respectively, with the rotation angle of the feedback rod being less than ±45 degrees. When calibrating an electric valve positioner, with the valve in the closed position, the signal value is exactly 4 mA. To ensure no seat load is generated, an auxiliary power supply is used in the valve design. Valve seat load is generated only when the control signal drops below 4 mA, but such a signal is generally not present in control systems. When closed, the valve seat is under full load. When the signal value is 3% to 5% of the operating value, an abnormal calibration is performed to position the valve on its seat. The above has introduced the calibration methods for electrical valve positioners. I hope it will be helpful to everyone in case they encounter similar situations while using them.