A separator with a helix assembly that includes a plurality of segments disposed end to end and forming an intermediate casing. Each of the segments has a tubular portion with a first circumferential edge and a second circumferential edge and a helical portion extending from the second circumferential edge. The tubular portions of the segments form an intermediate casing, while the helical portions of the segments form a spiral helix. The helix assembly further includes an inner casing concentrically disposed within the intermediate casing and coupled to the spiral helix.