Pressure comparison measurements between the CMI and the PTB in the range 0.07 MPa to 0.4 MPa

This report describes pressure comparison measurements in the range 0.07 MP a to 0.4 MPa between the Czech Institute of Metrology (CMI) and the Physika lisch-Technische Bundesanstalt (PTB) in the period 9 to 13 March 1998 at th e Pressure Section of the PTB, Braunschweig. The transfer standard used was a gas-operated piston-cylinder assembly with a ceramic piston of nominal e ffective area 10 cm(2) and a tungsten-carbide cylinder, installed in a pres sure balance base unit, model PG 7601, manufactured by DH Instruments, USA. The measurements compare the effective area of the transfer piston-cylinde r assembly as determined from dimensional data at the CMI with effective ar ea data obtained from pressure measurements (i) in gauge mode with the prim ary standard pressure balance and (ii) in absolute and gauge mode with the primary standard dual-cistern mercury manometer of the PTB. Both primary st andard instruments have been used in the international comparison measureme nts organized by the Consultative Committee for Mass and Related Quantities (CCM) of the Comite International des Poids et Mesures. It may be seen tha t geometrical measurement values of the effective area agree with results f rom the PTB and that the relative difference between the effective area is minimal: for the standard pressure balance, 3.4 x 10(-6) for absolute press ure, 3.4 x 10(-6) for gauge pressure; and for the dual-cistern mercury mano meter, 1.8 x 10(-6) for gauge mode. The relative difference between the exp erimental absolute and gauge mode for the dual-cistern mercury manometer is 1.5 x 10(-6).