A fluid separation device is provided with an outer housing and a rotor rotatably received within the outer housing. The rotor housing has a first end and a second end. The outer surface of the rotor and/or the inner surface of the outer housing is adapted to allow passage of a fluid component through the surface. The device further includes a flexible seal associated with one of the ends of the rotor and adapted to allow for rotational, non-axial, and axial movement of the rotor with respect to the outer housing.