With the wide application of pneumatic valves, the technology of pneumatic actuators is getting better and better. The gap between domestic pneumatic actuators and imported pneumatic actuators is also getting smaller and smaller, and there are more and more types. Now we will check the pneumatic actuators. The method is introduced as follows:
1) Calibration preparation and visual inspection
1. All test instruments must be energized and preheated 30 minutes in advance;
2. The pressure of the test air source must meet, 0.6±0.1Mpa,;
3. There is no obvious damage to the appearance of the actuator, no obvious dents in the air guide copper pipe, and the assembly is firm;
4. The length of the connecting screw of the position transmitter must meet the technical requirements of the tested actuator model; the plane formed by the connecting rod fastened on the transmitter shaft and the connecting screw should be perpendicular to the horizontal plane;
2) Inspection standards and methods
1. Fix the pneumatic actuator on the calibration platform, connect the air source, control air source and displacement detection connecting rod respectively; adjust the instrument on the calibration platform accurately;
2. Mechanical zero point calibration: input 4mA current signal (0%), the control gas signal should be 0.02Mpa, at this time the cylinder piston stroke should be zero; if it is not zero, the zero point can be adjusted by adjusting the nut on the zero adjustment screw ( The zero point is higher than the nut); the zero point and span need to be adjusted repeatedly; the zero point error should be ≤1%;
3. Mechanical full-scale calibration: input 20mA current signal (100%), control gas signal should be 0.10Mpa, at this time the cylinder piston stroke should be the upper limit; if it is not the upper limit, you can adjust the tension of the span tension spring To adjust the range (the range is smaller, the tension spring is loose, and the range is larger, the tension spring is larger); the zero point and range need to be adjusted repeatedly; the full range error should be ≤1%;
4. Positioning the midpoint of the mechanical range: After the zero point and range are adjusted, input a 12mA current signal (50%, 0.06Mpa), and adjust the position of the position transmitter connecting rod to keep it perpendicular to the horizontal plane at this point;
5. Full stroke deviation calibration: input control gas signal 0.02Mpa (0%), and then gradually increase the input signal 0.036, Mpa (20%), 0.052, Mpa (20%), 0.068, Mpa (60%), 0.084, Mpa (80%), 0.1, Mpa (100%), make the cylinder piston complete the stroke, the deviation of each point must be ≤1.5%;
