This volume contains papers presented at the 4th International Conference on Hydrocyclones, held at Southampton, U.K., on 23-25 September, 1992. Cyclonic devices, as a means of separating different fluid phases, are truly coming of age. Considerable fundamental research has been carried out leading to better design information which, together with advances in materials technology and broader fields of application, has resulted in much wider market acceptance. The volume provides a unique international forum for operators, suppliers, manufacturers and designers of equipment for the mineral processing, petroleum and process industries to present the theory, design and application of cyclonic devices in industry. The papers are divided into several main sections: fundamentals and new areas design and operation practical applications and development. The volume is the most up-to-date review of current developments in the technology.