This report describes the second CCM key comparison in capillary viscometry at nine national metrology institutes (NMIs), which was carried out between April and August 2006. Five NMIs, which do not maintain an independent viscosity scale, also took part in this comparison. One participant submitted changes to their originally submitted results for one liquid and requested that results be withdrawn for a second liquid.

Six samples of Newtonian liquids with nominal kinematic viscosities of 80 mm²/s at −40 °C, 20 mm²/s at −20 °C, 5 mm²/s at 20 °C, 1300 mm²/s at 20 °C, 40 mm²/s at 100 °C and 15 mm²/s at 150 °C were used to determine the degrees of equivalence between the individual NMIs and the proposed key comparison reference values (KCRV). From the total number of 54 measurements carried out by all the participating NMIs, 7 measurements (13%) showed deviations from the proposed KCRVs greater than were covered by the measurement uncertainties. This compares to 18 deviations (24%) out of 74 total measurements made in the first key comparison.

Linkage to the first key comparison is found at two points—approximately 1300 mm²/s at 20 °C and 40 mm²/s at 100 °C. For this key comparison, 13% of the measurements (3 out of 23) on these two points exceeded the proposed KCRVs by more than were covered by the respective measurement uncertainties.

For reference, the first CCM viscosity key comparison (CCM.V-K1) was conducted in 2002.

Main text. 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 kcdb.bipm.org/.

The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).