Inspection method of pneumatic actuator

1. Fix the pneumatic actuator on the check platform, and connect the air source, control air source and displacement detection connecting rod respectively; Calibrate the instrument on the check table accurately;

2, mechanical zero calibration: input 4mA current signal (0%), control gas signal should be 0.02Mpa, at the moment the cylinder piston stroke should be zero; If it is not zero, the zero can be adjusted by adjusting the nut on the zero adjusting screw (the zero is higher than the tight nut); Repeated adjustment of zero and range requirements; Zero error ≤1%;

3, mechanical full scale calibration: input 20mA current signal (100%), control gas signal should be 0.10Mpa, at the moment the cylinder piston stroke should be the upper limit; If it is not the upper limit, the range can be adjusted by adjusting the tightness of the range spring (the range is small to loosen the spring, and the range is large to tighten the spring); Repeated adjustment of zero and range requirements; Full scale error ≤1%;

4, mechanical range point positioning: zero and range alignment, input 12mA current signal (50%, 0.06Mpa), adjust the bearing of the connecting rod of the bearing transmitter, so that it at the point to maintain vertical with the horizontal plane;

5, full stroke error calibration: Input control gas signal 0.02Mpa(0%), and then gradually add input signal 0.036Mpa (20%), 0.052Mpa (20%), 0.068Mpa (60%), 0.084Mpa (80%), 0.1Mpa (100%), so that the cylinder piston to go complete stroke, The error of each point should be less than 1.5%;

6. Nonlinear error test: Input control gas signal 0.02Mpa(0%), and then gradually add the input signal until 0.10Mpa(100%), and then reduce the signal to 0.02Mpa(0%), so that the actuator to complete the stroke, and record the stroke value of each increase or decrease of 0.008Mpa signal pressure, its practical pressure, The nonlinear error between the travel relation and the theoretical value should be less than 1%;

7, positive and negative stroke variation test: the same as the nonlinear error test method, the practice of positive and negative pressure, stroke relationship, the same pressure value under the cylinder piston positive and negative stroke value of the maximum difference to less than 1%;

8, sensitivity test: respectively in the signal pressure 0.03, 0.06, 0.09Mpa stroke, add and drop pressure, test in the cylinder piston rod began to move 0.1mm when the required signal pressure change value, the maximum change is less than 0.2%;

9, piston cylinder tightness test: 0.5Mpa pressure access to any gas chamber of the cylinder, and then cut off the air source, in 10 minutes, the decline of the pressure in the cylinder should not exceed 0.01Mpa; does

10. Electric zero detection of azimuth transmitter: open the upper cover of azimuth transmitter and connect the wire; Input 12mA current signal (0.06Mpa), adjust the circular eccentric wheel in the transmitter at this moment, so that the black line above it is aligned with the white line above the circuit board; Then input 4mA current (0.02Mpa), at the moment can adjust the transmitter in the zero potentiometer to make the output current is 4mA; Electrical zero error should be less than 1%;

11, azimuth transmitter electrical full range detection: input 20mA current signal (0.1Mpa), at the moment can adjust the range potentiometer in the transmitter so that the output current is 20mA; Electrical full scale error should be less than 1%;

12. Calibration of full stroke error of azimuth response current: Input 4mA current (0%), and then gradually add input signal 8mA current (25%), 12mA current (50%), 16mA current (75%), 20mA current (100%), considering the linear displacement into Angle change of nonlinear error, 0%, 50%, 100% point reaction current error should be less than 1%. 25%, 75% reaction current error should be less than 2%;

13, azimuth reaction current positive and negative stroke variation test: the same as the cylinder positive piston reverse stroke variation test method, the practice of positive and negative azimuth reaction current, stroke relationship, the same reaction current value of the cylinder piston positive and negative stroke value of the maximum difference to less than 1%;

14. Make the verification record, fill in carefully each item according to the content on the verification record form, and the inspection personnel must sign;

15. After the above tests are completed and qualified, the terminal inside the azimuth transmitter should be inserted, the back cover should be tightened, and then the valve positioner air source inlet should be blocked with a plastic plug;