Abstract: An arrangement for treating a work object including a unique, unified method and apparatus for contaminant removal from the work object, wherein a laminar flow, ambient air stream passes through connected zones at lower pressure than ambient with particulate matter being filtered from the air stream.

Abstract: A metering arrangement for limiting the advance of the filter media in an automatic roll filter having a timer which periodically energizes a drive motor adapted to draw the media through the filtering zone of the apparatus. The arrangement includes a metering reel which is adapted to rotate in direct proportion to the lineal advance of the filter media, a magnet mounted on the reel which generates a magnetic field limited to a predetermined arc of the periphery of the reel, and a reed switch which is actuated by the magnetic field to signal an electrical circuit to shut off the drive motor after a preselected increment of the filter media has been drawn into the filtering zone of the apparatus.