This work is a contribution to the discovery and evaluation of new refrigerants. It has been stimulated by the uncertainty created by the Kyoto Protocol over the long-term availability of the hydroflorocarbons (HFCs) and also by the need for more knowledge of HFC-oil pairings. An economical method for testing refrigerants in terms of coefficient of performance (COP) and evaporative behaviour in a lubricated system is described. Part 1 describes the equipment, its instrumentation and operating procedures. Part 2 discusses the system output for four test refrigerants: two single fluids R134a and R22 and two test non-azeotropic blends each having a glide of around 9 K. Study of R22 was confined to evaporative behaviour. The ranking of refrigerants by COP and boiling length is given and the generality of use of these rankings is discussed. Copyright (C) 2000 John Wiley & Sons, Ltd.