An Approach to Synchronise Effective Areas of Pressure Balances

摘要

A method to synchronise effective areas of pressure balances is presented. By this method, the effective areas of piston-cylinder assemblies (PCAs) with their uncertainties determined from dimensional characteristics of the piston and the cylinder or from a calibration against reference pressure standards can be adjusted to achieve an optimal agreement with the effective area ratios determined by cross-float measurements between the PCAs. The approach is based on the weighted least squares' method and leads to minimum discrepancies between the initial effective areas and the cross-float area ratios on one side, and the synchronised effective areas on the other side. Examples of the new method's application to five gas-operated PCAs and five oil-operated PCAs of PTB, and to five gas-operated PCAs of NIMT, which are used as primary pressure standards in the two institutes, are presented.