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- Validation of a vibrating-wire viscometer: measurements in the range of 0.5 to 135 mPa'sPublication . Oliveira, Carla Padrel de; Caetano, Fernando J. P.; Fareleira, João M. N. A.; Wakeham, William A.The present article describes a novel vibrating-wire viscometer that has been shown to be able to measure viscosities up to 135 mPaâs, after calibration against water at 20 °C, to provide direct traceability to the primary reference for viscosity. For the purpose of validating the instrument, measurements of the viscosity of some selected fluids, including standard reference liquids with viscosity on the order of 100 mPaâs at 20 °C and 2,2,4-trimethylpentane with a viscosity of about 0.5 mPaâs at the same temperature, were performed. The results obtained show that the instrument is capable of performing viscosity measurements with an estimated overall uncertainty better than (0.8% over the range of (0.5 to 135) mPa's.
- Viscosity of R134a, R32, and R125 at saturationPublication . Oliveira, Carla Padrel de; Wakeham, William A.This paper reports the results of the measurement of the viscosity of R134a close to the saturation line in the vapor phase. The new measurements were carried out in a vibrating-wire viscometer specially constructed for the purpose, and the results have an accuracy of ±2%. In addition, the opportunity is taken to present a reevaluation of earlier measurements along the saturation line of the viscosity of R32 and R125. Improved equations of state for these fluids are now available and can be employed to generate improved values for the viscosity.