Understanding Uncertainty in Viscosity Measurement

This Application Note provides information relating to measurement precision in general, and the precision of kinematic viscosity measurements in particular. It provides a brief history and discussion of primary concepts relating to measurement uncertainty. The information was drawn primarily from the National Institute of Standards and Technology (NIST) Reference on Constants, Units, and Uncertainty and the NIST Technical Note 1297 1994 Edition. The Application Note concludes with a
practical example of uncertainty calculation for a CANNON viscosity reference material.

Over the years, many different approaches to evaluating and expressing the uncertainty of measurement results have been used. Because of this lack of international agreement on the expression of uncertainty in measurement, in 1977 the International Committee for Weights and Measures (CIPM, Comité International des Poids et Measures), the world’s highest authority in the field of measurement science (i.e., metrology), asked the International Bureau of Weights and Measures (BIPM, Bureau International des Poids et Mesures), to address the problem in collaboration with the various national metrology institutes and to propose a specific recommendation for its solution. This led to the development of Recommendation INC-1 (1980) by the Working Group on the Statement of Uncertainties convened by the BIPM, a recommendation that the CIPM approved in 1981 and reaffirmed in 1986 via its own Recommendations 1 (CI-1981) and 1 (CI-1986):