Tubular centrifugal duct fans are designed for commercial and industrial in-line applications that demand quiet, efficient and reliable air movement. They are used to exhaust air from or supply air to commercial and industrial applications, such as, general building ventilation, enclosed garages, paint spray booths, heat and smoke ventilation systems, restaurant and kitchen exhaust ventilation, historical buildings with limited roof space and restrictive duct lengths, and other applications where air is moved through a duct system against moderate static pressure.