A separator for removing particulate contamination from a flowing medium of a different density. The separator incorporates means such as a venturi for directing and accelerating the particulate into a predetermined location in the flow and a screen assembly located downstream of the director. The screen assembly extends across the location in the flow where particles are directed to enable the primary flow path of the medium to bypass the screens if need be. The screen assembly can be comprised of one or more stages which separate and entrap particles. The screen assembly may be spring mounted to accommodate variable velocity flow and may include means for regenerating the screens.