US Patent 7209350 Ventilation system for electrical of electronic equipment

A ventilation system for electrical or electronic equipment installed in an enclosure of a box having an air inlet and an air outlet for establishing a flow of air through said enclosure, the ventilation system having at least two air suction sources, namely a primary source and a secondary source, and a chest for mounting on said box beside the air outlet, said chest defining at least two separate cavities, both for connection to the air outlet, namely a primary cavity connected to the primary source, and a secondary cavity connected to the secondary source, in such a manner as to create two separate air exhaust circuits from the outlet of the enclosure.