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1. For the initial position deviation check, apply a signal pressure of 0.2 kg/cm2 to the diaphragm chamber; then increase the signal pressure to 1.0 kg/cm2 – the valve stem should move through its full stroke. After that, reduce the signal pressure back to 0.2 kg/cm2. Measure the stroke of the valve stem at 1.0 kg/cm2 and 0.2 kg/cm2, and the initial and final position deviations should not exceed the allowable values. 2. Full-stroke deviation verification: Apply a signal pressure of 0.2 kg/cm2 to the diaphragm chamber, then increase the signal pressure to 1.0 kg/cm2; the valve stem should move through its full stroke. The deviation over the full stroke of movement shall not exceed the allowable value. 3. Non-linear deviation verification: Apply a signal pressure of 0.2 kg/cm2 to the diaphragm chamber; then increase the signal pressure in the same direction to 1.0 kg/cm2 to cause the valve stem to move through its full stroke. After that, decrease the signal pressure in the same direction back to 0.2 kg/cm2, causing the valve stem to move through its full stroke in the opposite direction. During the rise and fall of the signal pressure, record the stem travel value corresponding to each signal pressure level every 0.08 kg/cm2 (5 points can be used for routine calibration). The maximum nonlinear deviation between the actual relationship curve of input signal pressure and valve stem stroke and the theoretical straight line should not exceed the allowable value. 4. Forward and reverse stroke accuracy verification: The verification method is the same as that for nonlinear deviation verification. According to the actual relationship curve between the forward and reverse signal pressures and the valve stem stroke, at the same signal pressure value, the maximum deviation between the forward and reverse stroke values of the valve stem should not exceed the allowable limit. 5. Sensitivity limit verification: Input the signal pressure to the diaphragm chamber; at pressures of 0.3, 0.6, and 0.9 kg/cm2, increase and decrease the signal pressure respectively, and measure the change in signal pressure when the valve stem moves by 0.01 mm. The maximum value of this change should not exceed the allowable limit.