High pressure comparisons between seven European National Laboratories:Range 50 MPa to 500 MPa

An inter-comparison in the high oil pressure range was arranged in 2005-2007. The participating laboratories were CMI/Czech Republic, Metas/Switzerland, MIKES/Finland, NMi-VSL/The Netherlands, PTB/Germany, SMD/Belgium and SP/Sweden. CMI, Metas, NMi-VSL and PTB are pressure laboratories of the primary level, and the three others are traceable to LNE/France. The transfer standard was a Desgranges & Huot piston-cylinder unit with a nominal effective area of 1,96 mm², mounted in a D&H 5316 balance body. The participants determined the effective area at ten nominal pressures from 50 MPa to 500 MPa in steps of 50 MPa. All the results were in a good agreement with the reference values, calculated as weighted means of the results from the four primary level laboratories. The results fully support the uncertainties claimed in the CMC tables of the participants. The transfer standard was not as stable as expected, and the uncertainties of the reference values were to some extent increased by the observed drift