A separation device (10, 50, 80) for separating a fluid, said fluid comprising multiple components, into at least two components comprising: a support structure (12, 52); at least one separation tube (14, 54) mounted on or within said support structure (12, 52) for rotation about an axis, wherein said at least one separation tube (14, 54) comprises one or more vanes (26, 27, 62) attached to or formed integrally with said separation tube (14, 54); at least one inlet (16, 56, 57) for introducing a flow of said fluid into said at least one separation tube (14, 54); and at least one outlet (18, 20, 31, 59, 66, 68, 76) for outputting at least one of said components therefrom, wherein the at least one outlet (18, 20, 31, 59, 66, 68, 76) comprises an overflow outlet (20, 31, 68), and the overflow outlet (20, 31, 68) comprises a vortex finder; wherein the said at least one separation tube (14, 54) is configured such that, in use, when said flow of said fluid is applied thereto, said separation tube (14, 54) is thereby caused to rotate on or within said support structure (12, 52) about said axis, thereby separating said fluid into at least two components, in which the rotation of the separation tube (14, 54) together with any rotational spin induced at the inlet (16, 56, 57) maintains or increases a spiral or rotating flow profile of the fluid, and the rotation of the fluid within the separation tube (14, 54) establishes a vortex in the fluid whereby a centrifugal force causes denser components of the fluid to accumulate towards the walls of the separation tube (14, 54) whereas the less dense components accumulate near said axis and are extracted from near said axis by the vortex finder. a support structure (12, 52); at least one separation tube (14, 54) mounted on or within said support structure (12, 52) for rotation about an axis, wherein said at least one separation tube (14, 54) comprises one or more vanes (26, 27, 62) attached to or formed integrally with said separation tube (14, 54); at least one inlet (16, 56, 57) for introducing a flow of said fluid into said at least one separation tube (14, 54); and at least one outlet (18, 20, 31, 59, 66, 68, 76) for outputting at least one of said components therefrom, wherein the at least one outlet (18, 20, 31, 59, 66, 68, 76) comprises an overflow outlet (20, 31, 68), and the overflow outlet (20, 31, 68) comprises a vortex finder; wherein the said at least one separation tube (14, 54) is configured such that, in use, when said flow of said fluid is applied thereto, said separation tube (14, 54) is thereby caused to rotate on or within said support structure (12, 52) about said axis, thereby separating said fluid into at least two components, in which the rotation of the separation tube (14, 54) together with any rotational spin induced at the inlet (16, 56, 57) maintains or increases a spiral or rotating flow profile of the fluid, and the rotation of the fluid within the separation tube (14, 54) establishes a vortex in the fluid whereby a centrifugal force causes denser components of the fluid to accumulate towards the walls of the separation tube (14, 54) whereas the less dense components accumulate near said axis and are extracted from near said axis by the vortex finder.