Inspection method of pneumatic actuator 2

7. Variation test of forward and reverse strokes: the same as the nonlinear deviation test method, in the relationship between the actual forward and reverse pressure-stroke, the maximum difference between the forward and reverse stroke values of the cylinder and piston under the same air pressure value should be ≤1%;

8. Sensitivity test: increase and decrease the air pressure at the stroke of the signal pressure of 0.03, 0.06, and 0.09mpa respectively, and test the signal pressure change value required when the cylinder piston rod starts to move 0.1mm, and the maximum change should be ≤ 0.2%;

9. The tightness test of the piston cylinder: connect the pressure of 0.5 mpa to any air chamber of the cylinder, and then cut off the air source. Within 10 minutes, the drop value of the pressure in the cylinder should not exceed 0.01 mpa; ※

10. Electrical zero point detection of the position transmitter: open the position cover and connect the wires; input a 12ma current signal (0.06 mpa), and adjust the circular eccentric wheel in the transmitter at this time so that the black line on the top is on the top of the circuit board The white line is aligned; then input 4ma current (0.02 mpa), at this time, the zero-adjustment potentiometer in the transmitter can be adjusted to make the output current 4ma; the electrical zero error should be ≤1%;

11. Electrical full-scale detection of position transmitter: input 20ma current signal (0.1 mpa), at this time, the range-adjusting potentiometer in the transmitter can be adjusted to make the output current 20ma; the electrical full-scale error should be less than or equal to 1%;

12. Position feedback current full stroke deviation calibration: input 4ma current (0%), then gradually increase the input signal 8ma current (25%), 12ma current (50%), 16ma current (75%), 20ma current (100%) , considering the nonlinear error of linear displacement converted into angle change, the feedback current error at 0%, 50% and 100% points should be ≤1%, and the feedback current error at 25% and 75% points should be ≤2%;

13. Position feedback current forward and reverse stroke variation test: the same as the cylinder forward and reverse stroke variation test method, in the actual forward and reverse position feedback current-stroke relationship, the maximum difference between the cylinder piston forward and reverse stroke values under the same feedback current value The value should be ≤1%;

14. Make the verification record, fill it out item by item according to the content on the verification record form, and the inspector must sign it;

15. After the above tests are completed and qualified, the wiring terminals in the position transmitter should be inserted, the back cover should be tightened, and then the air source inlet of the valve positioner should be blocked with a plug;