The present study concerns the separation of fine liquid-liquid dispersions having mean droplet diameters between 20 and 100 mum by phase inversion without bed formation. The influence of some operating parameters such as continuous phase flow rate, nozzle diameter and mean droplet diameter on the separation efficiency is studied. As can be seen, good operating conditions always lead to high separation efficiencies and all droplets having diameters above 50 mum can be practically removed. On the basis of a dimensional analysis relationships are given which allow designing separators based on the phase inversion method operating at low flow velocities in the nozzles according to the physical properties of the system, the separator characteristics, the droplet diameter and the desired efficiency. (C) 2003 Elsevier B.V. All rights reserved.