A bilateral comparison of a 1 mg - 20 kg weight set calibrated by subdivision/multiplication

Project Description

Recently, NCM has set up a method for the calibration of weight sets by the subdivision/multiplication principle. Since the accreditation of DFM’s mass calibration facilities in 1992, DFM has performed highly automated calibrations on a routine basis using the subdivision/multiplication principle.The purpose of this comparison is the test the consistency of the subdivision/multiplication algorithms used by NCM and DFM, respectively. NCM will act as the pilot laboratory for the comparison and will provide the mass standards to be circulated. The volumes of the mass standards will be measured by DFM.

The comparison was funded by the Royal Danish Ministry of Foreign Affairs under the project “Prepackaging and Metrology in Bulgaria”; (BUL0019).

Final Report 2004-05-10

The comparison has been completed and the report can be downloaded here>>.

A bilateral comparison on the measurement of mass has been carried out between the National Metrology Institutes NCM, Bulgaria and DFM, Denmark. A set of stainless steel weights in the range 1 mg to 20 kg provided by NCM was used as transfer standards. The weights were first calibrated at NCM using a recently introduced subdivision/multiplication procedure. The weight were then transported to DFM and calibrated using the well-established subdivision/multiplication procedure of DFM. In order to be able to compare mass values rather than conventional values, DFM measured the volumes of the weights in the range 1 g to 1 kg by hydrostatic weighing in flour-carbon (FC 40). In order to monitor any changes in mass due to submersion into FC 40, the volume measurements were followed by an additional calibration of the weights 1 g to 1 kg at DFM. Finally, the weights were transported back to NCN, where a second calibration by NCM was carried out.

The results were generally satisfactory and support the CMC entries submitted by NCM.