Design And Development Of Automatic Pressure Calibration System

The pressure was a very important test parameter, and a variety of pressure instruments were designed to measure the pressure parameter, their performance was directly related to the quality of test results. Therefore, it was necessary to do pressure calibration to the pressure instruments regularly. Based on the commercial air conditioning pressure sensor’s pressure calibration requirements, the author designed and developed an automatic pressure calibration system with pressure source and inner pressure module to realize automatic pressure calibration.Firstly, the author described and analyzed the advantages and disadvantages of the automatic pressure calibration method based on the piston gauge and the method of using the pressure sensor. And put forward the idea of combining the piston gauge and the pressure sensor technology. Then the author reviewed the overall automatic pressure calibration system from the working principles, design programs, technical specifications and other aspects, including the standard pressure generating device, the standard pressure module and the control and display module. Secondly, the author introduced the various components of the automatic pressure calibration system. The standard pressure generating device used the motor to drive pressure cylinder to output the standard pressure. The standard pressure module used the high precision standard pressure sensor to achieve real time detection of the system pressure, and was equipped with fixed temperature compensation. The control and display module used the PLC controller and the touch screen.Thirdly, due to the irregularity of pressure control, the author studied on the control methods of the standard pressure. Compared with traditional PID controller, the author used a fuzzy controller to achieve more accurate control of the standard pressure.Finally, the experimental study showed that the designed automatic pressure calibration system can generate standard pressure point by point automatically in the range of0-6MPa. The experiments were operated on the commercial air conditioning pressure sensor strictly following relevant provisions of the pressure sensor test statutes. It significantly improved the pressure calibration efficiency. Accuracy of the created pressure was0.05%FS, the standard pressure’s repeatability was less than0.05%and the uncertainty of the automatic pressure calibration system was8.241839×10-4MPa, which satisfied the requirements of the design objectives.