454 / | HD | VENTILATION |
339 | DF | HAVING OUTLET AIRWAY {7} |
341 | DF | .~ With air pump {9} |
347 | .~.~ Having readily movable air regulating louver,damper, or cover {5} | |
348 | DF | .~.~.~> Continuously horizontal damper panel |
349 | DF | .~.~.~> Ceiling mounted air pump |
350 | DF | .~.~.~> Wall mounted air pump {1} |
352 | DF | .~.~.~> Plural damper panel |
353 | DF | .~.~.~> Including backdraft preventer |