Abstract: The method of operating rotating separator apparatus, to which fluid, including gas and liquids is supplied in a fluid jet via a nozzle, which includes separating the liquids from the gas in the stream, at a first zone within the rotating apparatus, and separating the liquids into liquids of differing density at a second zone within the apparatus. The separated liquids are removed via two open weirs which isolate the liquids in the separating zones from the shear forces from scoops within the weir passages. Longitudinal ribs may be provided for structural support, coalescence promotion and fluid recirculation inhibition.