Abstract: A method for adjusting an interface formed during operation between a specific light liquid phase and a specific heavier liquid phase to a wanted radial level in a centrifugal separator, in which the separation chamber is emptied of its contents and the inlet opening is brought to a radial inner position in the outlet chamber, after which a pre-determined volume of the specific heavier liquid phase is supplied to the separation chamber and the mixture of the two liquid phases is supplied to the separation chamber via the supply conduit and the inlet chamber whereby the separation chamber is filled up and an interface between the two liquid phases is formed, which is displaced radial outwardly, the displaced specific heavier liquid phase then being pressed radial inwardly in the outlet channel and further into the outlet chamber.