Abstract: A powder processing system having a processing vessel into which powder is pneumatically supplied and an exhaust plenum that communicates with the processing vessel through an exhaust port. A filter is located at the exhaust port for filtering air borne powder from the air flow exiting the processing vessel, and a reverse pulse air filtering device is provided for selectively removing accumulated powder from the filter. The cleaning device includes a nozzle having a first portion within the air plenum and a second portion within the air filter, and a plunger is mounted on the first filter portion for movement to an exhaust port closing position as an incident to the direction of pressurized air through the first portion of the nozzle for enabling pressurized air from the second portion of the nozzle to thereupon be directed through the filter without hindrance of air exiting the processing vessel.