Pressure comparison in the range from 0.8 to 8 MPa between the UME (Turkey) and the CNR-IMGC (Italy) in gas media and gauge mode

Abstract

A bilateral study was carried out at the Pressure and Vacuum Laboratory of the UME in cooperation with the CNR-IMGC (Italy) and the UME (Turkey), in October 1996. Two piston-cylinder assemblies were compared by application of the cross-floating method and the comparison was made in the pressure range from 0.8 to 8 MPa in gas media (gauge mode). The IMGC took only one of its piston-cylinder assemblies to the UME which was compared with a UME piston-cylinder assembly. Six measurement cycles were run and forty-two cross-floating equilibrium points were obtained between the two pressure balances. The sensitivity of the cross-floating equilibrium between the two pressure balances ranged from 3.3 to 1 ppm; best sensitivities were obtained at highest pressures. A new value of the effective area of the UME piston-cylinder assembly was derived as a result of this comparison with an uncertainty of 22.3 ppm (2σ level). Considering the previous value of the UME piston-cylinder effective area, this comparison confirmed the agreement of Italian and Turkish pressure scales in gas media from 0.8 to 8 MPa inside the combination of respective declared uncertainties of 11 ppm for the IMGC and 25 ppm for the UME, even at the 1σ level.