  New correlations between viscosity and surface tension are proposed and
checked for saturated normal fluids. The proposed correlations contain three or
four adjustable coefficients for every fluid. They were obtained by fitting 200
data points, ranging from the triple point to a point very near to the critical
one. Forty substances were considered, including simple fluids (such as rare
gases), simple hydrocarbons, refrigerants, and some other substances such as
carbon dioxide and water. Two correlation models with three adjustable
coefficients were checked, and the results showed that the one based on the
modified Pelofsky expression gives the better overall results. A new
4-coefficient correlation is then proposed which clearly improves the results,
giving the lowest overall deviations for 32 out of the 40 substances considered
and absolute average deviations below 10% for all of them.
