Abstract: The present invention is directed to dust filtering apparatus comprising a cylindrical housing separated by a horizontal partition into dirty and clean air chambers with a plurality of radially spaced bags attached to the partition hanging in the dirty air chamber; positioned in the clean air chamber is a rotating cleaning arm supplied by a source of high pressure air including a nozzle means positioned to direct a high velocity jet of air into the bag openings in the partition through a venturi means attached to the rotating arm in spaced alignment from the nozzle means whereby the high velocity jet passing through the venturi entrains additional air momentarily into the individual bag being back-washed, and a closure plate on the arm concentrically aligned with the venturi and nozzle to momentarily retain the entrained air within the bag opening.