Viscosity of water in the region around the critical point

Viscosities of water have been measured in the temperature range from 573.21 K to 715.57 K along five isobars (19, 21, 23, 25, and 28 MPa). The measurements were carried out with a high temperature and high pressure capillary viscometer which was established on the basis of Poiseuille Law. The total uncertainties of temperature, pressure, viscosity measurements is estimated to be less than ±0.06 K, ±0.025%, and ±1.4%, respectively. The aim of this study is providing new data to check the accuracy of the IAPWS Formulation 2008 in the region around the critical point where few experimental data were reported. The average absolute deviation between the experimental values and the calculated values from the IAPWS Formulation 2008 is 1.4%, the maximum absolute deviation is 4.4%.