Abstract: Identical plates of essentially box-like form in which one sidewall of the box is notched out, and a transverse sidewall opposite the notch removed, the plates being stacked edgewise to form a duct assembly with alternatingly appearing openings at the top and bottom and on the front and rear side where the cutouts are positioned. The respective top and bottom openings are connected, respectively, to an ambient air manifold and a blower, and to the interior of the electronic cabinet, with the side cutouts facing, respectively ambient air and the interior of the cabinet to establish two separate air flow circuits and provide for dust-free and contamination free ventilation of the interior of the electronic cabinet while establishing efficient heat exchange by forced air flow of ambient air parallel to the ducts carrying dust-free, but heated air from the cabinet.