AIR HOLDING DEVICE AND EXHAUST AIR BOX, IN PARTICULAR USABLE IN SAID DEVICE

摘要

The invention relates to an air holding device comprising a channel system (44) raised from a suction opening (70) disposed at a height of a workstation generating dirty air or vapours and leading to at least one outlet opening (56a). An exhausting fan (52) is placed between a prefilter (60) and at least one odour filter (62a). The channel system (44) is embodied in the form of an exhaust air box (50) disposed downstream of the exhaust fan (52). The lateral surface of the exhaust air box (50) comprises an air inlet (64) which is connected to the downstream side of the exhausting fan (52). The other lateral surfaces are selectively provided with air outlet openings covered respectively with an odour filter having an adjustable air resistance. Said odour filter (62a) is preferably consists of a foam material coated with active carbon and the air resistance thereof is selectable according the thickness and/or porosity of the foam material. The size of the outlet opening (56a) in combination with a selectable air resistance of the odour filter (62a) makes it possible of reducing the exhaust air mean resistance to a desired value downstream of the odour filter without spoiling an ambient space.