Abstract: A hood assembly for at least partially defining an enclosure in which two or more non-parallel rapidly moving air streams cooperate to entrain minute air borne particles in the enclosure to recover the latter and prevent the escape of the particles through an opening in the forward part of the enclosure. The air defining the air streams may in whole or in part be discharged to the ambient atmosphere substantially free of entrained air borne particles, or the air may be sequentially recycled through the enclosure. The hood assembly is particularly adapted for paint spray booths, but is equally useful and effective, when the air borne particles constitute smoke or fumes.

Abstract: An exhaust hood vented to the atmosphere comprising a double-walled stack and a double-walled hood structure where the gap between the walls of the stack and the hood are arranged for communication. A first blower is mounted on the exterior end of the stack for ingesting exterior air into the gap between the walls, with this ingested air flowing downwardly to be injected along the interior surfaces of the hood. A second blower is mounted in the stack for withdrawing the combination of the injected air and any fumes collected in said hood.