Realisation of the liquid pressure scale from 0.5 MPa to 1.6 GPa at PTB

The pressure scale in liquids is realised in the range of about 0.5 MPa–1.6 GPa using several primary pressure balances and pressure-measuring multipliers. At pressures below 10 MPa, the SI traceability of the pascal to the length unit is achieved by dimensional measurements on pistons and cylinders of assemblies of 5 cm 2 nominal effective area. At higher pressures, where the accuracy of the pressure measurement is dominated by uncertainty of the pressure distortion coefficient, the latter is determined by measuring the elastic constants of the piston-cylinder materials and application of appropriate theories and calculation methods. From 1 GPa to 1.6 GPa, specially developed pressure-measuring multipliers are used. With these pressure measuring instruments and their characterisation by advanced methods the pressure measurements and calibrations in the range from 0.5 MPa to 1.6 GPa became possible with relative standard uncertainties from (5–130) parts in 10 6 .