EURAMET Key Comparison EURAMET.M.D-K4.2020: Hydrometer calibration comparison from 600 kg/m³ to 2000 kg/m³

Main text This report presents the results of the key comparison EURAMET.M.D-K4.2020 (EURAMET 1496) that covered the calibration of high-resolution hydrometers for liquid in the density range 600 kg/m3 to 2000 kg/m3 at the reference temperature of 20 oC. Nine laboratories participated in this key comparison, eight European national metrology institutes and one from Asia Pacific metrology: NIM from China. The participating laboratories were initially divided into two petals linked by two density laboratories: INRIM and PTB. In each petal, four similar transfer standards, hydrometers in the density range 600 kg/m3 to 2000 kg/m3 are used. The equipment used by the participants was found to have very similar characteristics. Most of the declared relative uncertainties were within the 5x10-5. The results of all participated laboratories have been linked to the CIPM key comparison CCM.D-K4 by INRIM and PTB. Discrepant results have been reported for three laboratories, which, however, do not affect their CMCs. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/. The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).