Design of semi-automated calibration system for pressure balances

In this study, a digital manometer was used as a transfer standard to perform calibration of a pneumatic pressure balance. The same pressure balance was calibrated with the cross-floating method based on falling rate determination (FRD). Average of differences among the effective area results show an agreement of less than 10 ppm between the digital manometer-assisted calibration (DMAC) method and the FRD method. The method in which a digital pressure gauge is used as a transfer standard not only facilitates calibration but also enables the automation of pressure balance calibration. Full automation of pressure balance calibration requires an automatic mass loading system for both the reference instrument and the device under test. Since there is a lot of different kinds of pressure balances, it is nearly impossible for a pressure metrology laboratory to have an automatic mass-handler system for every type of pressure balance. Therefore, a more efficient way in which automated mass-handler systems are not required .., a semi-automatic calibration system, is designed. For that purpose, two different calibration procedures, increasing-decreasing cycles, and pressurize-vent (P-V) procedures are performed and compared. The equivalence of procedure results makes the semi-automated calibration design of pressure balances possible. The most distinguishing advantages of a semi-automated calibration system are the applicability to any type of pressure balance and low cost compared to full automation.