A method for pre-separation of multi phase fluids of liquid-liquid phase and/or liquid-gas phases and/or gas-liquid phases, is disclosed, wherein one or more of the phases is suspended in water with bubble /drop/particle sizes in the sub micron and micron area and/or fine particular organic or inorganic matter is present in one or more of the phases, and where the device is placed in or in connection to a cyclone or flotation tank. The method is characterized by the fluid phases being made to flow through a tube which forms a spiral shape, in order to bring about an initial phase separation (coalescence) in the spiral shape, and the phases being led continuously tangentially out of the spiral shape in a cyclone—or flotation chamber wherein the further separation is generated. An apparatus to accomplish the method and applications thereof are also disclosed.