A continuous separating tank is to be designed to follow after a water washing plant for liquid oil. Estimate the necessary area for the tank if the oil, on leaving the washer, is in the form of globules 5.1 x 10-5 m diameter, the feed concentration is 4 kg water to 1 kg oil, and the leaving water is effectively oil free. The feed rate is 1000 kg h-1 , the density of the oil is 894 kg m-3 and the temperature of the oil and of the water is 38°C. Assume Stokes' Law. Viscosity of water = 0.7 x 10-3 N s m-2 . Density of water = 1000 kg m-3 . Diameter of globules = 5.1 x 10-5 m