Temperature and volume dependence of the viscosity of water and heavy water at low temperatures

New measurements have been made for the viscosity (77) of light and heavy water between the temperatures of 255.65 K and 298.15 K at pressures up to approximately 375 MPa with a falling-body viscometer. A revised correlation function is used to represent the results as a function of temperature and molar volume (V) with a standard deviation of +/-0.2% for both H2O and D2O. The overall uncertainty is estimated at +/-1%. Comparison of the two sets of data shows that they are consistent with the correlation eta(D2O,T,V) = 1.0544eta(H2O,T - 6.498 K,V) where 1.0544 is the square root of ratio the molar masses and 6.498 K is the thermal offset proposed by Robinson and co-workers.