This International Standard specifies a method for measuring the ability of petroleum oils or synthetic fluids to separate from water at a specified temperature. NOTE 1 The normal test temperature is 54 “C + 1 “C, but this may be increased to 82 “C + 1 “C for products with a viscosity above 90 mm2/s at 40 “C. Other test temperatures may also be specified. This test method was developed specifically for steam-turbine oils in the viscosity range 32 mm /s to 95 mm2/s at 40 “C, but it may be used to test the water separability of oils of different types and viscosity ranges, and also to test synthetic fluids. It may be unsuitable for high viscosity products where it is apparent that insufficient mixing of oil and water occurs. NOTE 2 The identical procedure is used for synthetic fluids with a density greater than 1000 kg/m3 at 15 “C, but it should be noted that the water will tend to float on the emulsion or liquid.