A comparison of primary platinum-iridium kilogram mass standards among eighteen European NMIs

S. Davidson

Abstract

The kilogram is unique among the base SI units in being the only one defined by an artefact rather than with relation to naturally occurring physical constants. A major problem with maintaining the traceability of the mass scale is the inherent instability of the kilogram artefacts. National standard kilograms accrete surface contamination over time which leads to an increase in their mass values. Without reference to the international prototype kilogram it is difficult to assess the magnitude of this mass gain and the traceability of measurements is compromised to some extent. This comparison examined the values of the national standard kilogram of 18 European NMIs, each of which uses an algorithm to predict the mass gain of their national standard. The results have been used to evaluate the accuracy of these algorithms and also to recommend a best-fit algorithm for the modelling of mass gain of national standard kilograms.

Keywords

mass gain, kilogram, SI units, national standards

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IMEKO-TC3-2007-032u.pdf

DOI

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IMEKO TC

TC3 - Measurement of Force, Mass, Torque, and Gravity

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