Vibrating Wire Viscometer with Nominal Wire Diameter of 0.15 mm:  Measurement of the Viscosity of Two Certified Reference Fluids, with Nominal Viscosities at T = 298 K and p = 0.1 MPa of (16 and 29) mPa·s, at Temperatures between (298 and 353) K and Pressures below 55 MPa

We have measured the viscosity of certified reference materials N10 and S20 with nominal viscosities at T = 298 K and p = 0.1 MPa of (16 and 29) mPa·s, respectively, at temperatures in the range (298 to 353) K and pressures between (0.1 and 55) MPa with a vibrating wire viscometer. This viscometer had a nominal wire diameter of 0.15 mm and provided viscosities with an estimated expanded (k = 2) uncertainty of ±2 % over the viscosity range (3 to 70) mPa·s. The latter value represents about half the upper operating viscosity of this vibrating wire that is about 150 mPa·s. The measured viscosity was compared with values predicted by interpolation expressions for N10 and S20 that represents the measured viscosities of different lots of the same fluids to within ±2 %. The results reported here have an average absolute deviation from those interpolation equations of about 2.4 % for N10 and 2.7 % for S20. These differences are within the combined estimated uncertainties of the measurements.