The final report for CCM.M-K7: key comparison of 5 kg, 100 g, 10 g, 5 g and 500 mg stainless steel mass standards

In order to show equivalence in mass standards calibration among National Metrology Institutes (NMIs) of member countries of the "Comité international des poids et mesures" (CIPM), key comparisons (KC) of mass standards have been carried out under the auspices of the "Comité Consultatif pour la Masse et les Grandeurs Apparentées" (CCM). This key comparison of 5 kg, 100 g, 10 g, 5 g and 500 mg stainless steel mass standards was based on the decision of the CCM during the 12th meeting held in 2010 at the Bureau International des Poids et Mesures (BIPM). KRISS (Republic of Korea) and PTB (Germany) acted as pilot laboratory and co-pilot laboratory, respectively. The results were evaluated with the Monte Carlo method using measurement values based on participants' reference standards calculated following the recent BIPM amendments in 2015. Regarding participant results, VNIIM (100 g and 5 g) were not consistent with the key comparison reference values within their expanded uncertainties with the coverage factor, k = 2.