A comparison between seven National Measurement Institutes to evaluate inert gas transfer of mass standards against current best practice.

A study between seven National Measurement Institutes to evaluate the benefit of transporting stainless steel standards between institutes in inert gas/vacuum compatible storage vessels compared with current comparison best practice. One standard in each group was also cleaned before the measurements to compare this approach with current best practice. The results showed significant correlation in the absolute mass values obtained for the standards with the institute at which they were measured, suggesting that the mass changes observed were principally due to the realisation of the mass scale at each institute. After normalising the results to reduce the influence of the reference mass values no significant differences were found between the different transport methods and in the case of one group of measurements current best practice demonstrated the best stability.