Abstract: A refrigerating unit having at least one refrigerating machine oil using polyol ester system oil as its base oil in at least one refrigeration cycle using at least one hydrofluorocarbon system refrigerant as a refrigerant, the present invention sets the purity of hydrofluorocarbon system refrigerant to the level higher than 99.95 wt % and the mixing of chlorine system refrigerant to the level lower than 80 ppm. In addition, the performance and reliability of refrigerating unit using the hydrofluorocarbon system refrigerant such as R134a can be enhanced by making the said polyol ester system oil to be the chemical compound of particular physical properties, by suppressing the equilibrium water content of refrigeration cycle and by limiting the residual chlorine volume.

Abstract: A lubricant for a refrigerating unit uses a hydrofluorocarbon system refrigerant with a polyol ester system oil as its base oil. The purity of hydrofluorocarbon system refrigerant is set to a level higher than 99.95 wt % and the mixing of chlorine impurity in the system refrigerant is set at a level lower than 80 ppm. The performance and reliability of a refrigerating unit using the hydrofluorocarbon system refrigerant, such as R134a, can be enhanced by making the polyol ester system oil of a chemical compound having particular physical properties, by suppressing the equilibrium water content of refrigeration cycle and by limiting the residual volume.