Comparison of mass standards of the kilogram (stainless steel)

Project Description

Two cylindrical stainless steel kilogram standards are currently being circulated along with the platinum-iridium kilograms involved in Project 509. As with the platinum-iridium comparison the circulation of the standards started in February 2001. The two standards are currently on the third leg of the comparison, which involves five legs in all – the weights returning to NPL between each leg. Each participating laboratory has one month in which to perform the measurements. The comparison is slightly behind schedule but it should be possible to make up the time when the weights next return to NPL. Nine of the seventeen participants had completed their measurements.

The comparison is due for completion early in 2003.

Enquiries have been received from several additional laboratories wishing to participate in the comparison. It is planned to circulate an additional pair of standards in parallel with the first pair to accommodate the additional participants. A timetable for the circulation of the second set of stainless steel kilogram standards has been drafted and sent to the additional participants. The circulation of these standards will start in April 2002 by which time the stability of the second set of standards will have been established. The completion of these additional measurements will co-inside with the end of measurement on the original travelling standards (early 2003).

Initial results for the comparison indicate that the calibration data is broadly equivalent to that of the previous EUROMET stainless steel comparison (project 215)


Progress Report

All measurements have been completed.

The final comparison report has been circulated to all participants and was agreed at the Mass & Related Quantities TC Meeting held at INRIM in March.

Publication of the comparison report is underway prior to the results being submitted to the BIPM Key Comparison Database.


Further Information

Project should be proposed to the SMT programme as a concerted action by the Euromet Consultative committee