Precise Comparison between Gas and Hydraulic Pressure Balances

Abstract

To improve consistency between gas and hydraulic pressure standards, two methods for comparing pressures of different mediums generated by gas and hydraulic pressure balances are examined. One is the method to use a gas-liquid exchanger and another is the method to use a liquid-lubricated pressure balance. The pressure range compared is0.5MPa to7MPa. In either method, a precise pressure transducer was used as a comparator to determine the equilibrium state between two pressure balances. In this paper, the comparison results and their uncertainties obtained from the respective methods are presented. From the results, it was shown that the results obtained from both methods were agreed within the combined standard uncertainty in all the pressure range compared and the relative difference was sufficiently small compared with the uncertainties obtained from the respective methods. Therefore, it can be stated that both methods adopted in this study are reliable to comparegas and hydraulic pressure balances precisely.