Ever since their introduction in the early thirties, the halogenated hydrocarbon compounds have found increasing use for industrial and commercial applications as refrigerants. These refrigerants are stable, nonflammable, odourless, organic compounds that h.ave a low toxicity and a high electrical resistance.

One of the essential prerequisities for an efficient design of a refrigeration system, or any other, that utilizes a certain refrigerant is the knowledge of the thermophysical properties of that particular fluid. One of the thermophysical properties which is known with the least accuracy over a range of states and phases is the viscosity. Diversified industrial application of the halogenated hydrocarbon compounds call for accurate information of their viscosity and its dependence on pressure and temperature for prediction of fluid flow and heat transfer phenomenon. Furthermore, accurate data can yield important molecular parameters and also thermodynamic property data for a given substance.