A stairwell pressurization system may be installed in either new or existinglow-rise orhigh-rise buildings and has at least one air duct and a fan system consistingof one or more fanswhich are operable to force substantially smoke-free air into the duct under apositive pressure.One or more air outlets are provided on the duct in the stairwell in thevicinity of each hallwayexit door leading into the stairwell. The air outlets are most preferablyvertically elongated andoriented so as to direct air from the duct at the opening edge of thestairwell entrance door. Theair outlets are electrically, electronically or physically connected to thestairwell door so as to beselectively opened or closed with the movement of the adjacent door. In asimplifiedconstruction. one of the elongated air outlets opens into the duct and isnormally maintained in anon-air flow position by a baffle door which is moved to open or close the airoutlet. Thestairwell entrance door has one end of a pulley cable coupled thereto, withthe other end coupledto the baffle door. The baffle door is connected by a pivot and is biased in aclosed position by aspring. As the stairwell entrance door is swung open. the pulley cable isdrawn therewith.moving the baffle door so as to be opened together with the stairwell exitdoor. Air is thendirected from the pressurized air duct through the elongated air outlet andalong the open edge ofthe stairwell door. As the door progressively opens, the air outlet openswider to direct more airfrom the pressurized air duct at the stairwell door through an elongated airoutlet.
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