**R428A**

R428A (also known as RS-52) is a zeotropic mixture consisting of 69.4% weight % R125, 25.6% R143a, 1.5% propane and 3.5% isobutane. It is considered to be a replacement fluid for R22 and R502. It has a molar mass of 107.53 kg/kmol.

Property data for R428A are provided using a generalized equation of state fitted by F-Chart Software using thermodynamic property data from the manufacturer and generated by REFPROP. The model is applicable for temperatures between 170 K and 530 K with pressures up to 50 MPa. The reference state is saturated liquid at 0 C for which specific enthalpy and entropy are 200 kJ/kg and 1.0 kJ/kg-K, respectively.

Transport properties are estimated using a corresponding states approach as suggested in:

Klein, S.A., McLinden, M.O., and Laesecke , A., "An improved extended corresponding states method for estimation of viscosity of pure refrigerants and mixtures", Int. J. of Refrigeration, 20, pp. 208-217, 1997

McLinden et al., "An extended corresponding states model for the thermal conductivity of refrigerants and refrigerant mixtures", Int. J. of Refrigeration, 23, pp. 43-63, 2000