Abstract: A device for introducing a low turbulence air displacement flow into an enclosed space, has a first housing section enclosing an air distribution space having an air inlet on one side and air flow passages through another side, and a second housing section having a perforated outer jacket and a non-perforated central core pipe. One central air flow passage connects the core pipe to the air distribution space. A ring of holes or a ring gap leads into a ring space formed between the perforated jacket and the core pipe. A third air passage permits forming an air skirt around the outer surface of the jacket. Control elements permit selectively opening and closing the flow passages, so that all or part of the fresh air may pass through the core pipe and air skirt or through the ring space. The perforated jacket may have a cylindrical portion and a frustum portion connecting the cylindrical portion to a perforated bottom plate.

Abstract: Angular sections form frames which can be fitted together in the frame plane in modular fashion. Legs of the sections are formed so that through two interconnected legs of adjacent frames notches of T-shaped cross-section result, into which hammer head-shaped ends of pull rods can be introduced. By means of the pull rods, ledges can be pressed against filter and/or light fixture housings, which in this manner are pressed against legs of the profiles on the opposite housing side, adjacent frames thus make it possible in a correspondingly compact model to attach filters and light fixtures without the distance between two adjacent filters or between a filter and a light fixture occupying a width that would impair the flow profile of the air issuing from the filters.