Abstract

A ventilated enclosure is formed by an air duct, one end of which is closed ff by a partition pierced with ventilation apertures and the other end of which is closed off by a wall to which is attached at least two fans and which is provided with openings through which air drawn into the interior of the enclosure from its exterior is passed. Each fan is provided with a detection device for detecting inadequate ventilation. The detection device is positioned in the area which is swept by the stream of air which is produced by the associate fan when in operation and generates a signal when the output of air from this fan falls below a predetermined limiting value. Each detection device consists of a thermal detection element designed to emit a signal when its temperature becomes equal to a predetermined temperature threshold and an air non-return casing. The air non-return casing contains the thermal detection element and is arranged to have passed through it only a fraction of the air output from the associated fan. This fraction of air output is such that, when the output from the fan is equal to the said predetermined limiting value, the temperature which prevails within the casing is equal to the said predetermined threshold.