|Standard round gravity ventilators are available in 12, 20, and 24 - inch diameter throat sizes. Other sizes up to 48 - inch available through special orders. 26 gauge inner and outer bands, rainshield, and base assembly are assembled with 4 pre-formed baffles into a simple yet sturdy ventilating unit. This design achieves a free un-obstructed flow of ventilated air. The addition of a vertical-lift type damper completes the weather-tightness of the unit. The damper is supported in the open position by 4 strong springs and is closed by a 5' long pull chain (longer lengths available on request). Damper may be locked in any position by the use of an optional key type chain lock (please specify when ordering.) Ventilator may be furnished without damper if desired. However, overspray or driven rain may enter the vented space. Ventilator with damper may function as a smoke exhaust vent by including a fusible link in the chain operator. Assembly is completed by the installation of a 4 x 4 bird screen in the opening between the inner band and the rainshield to resist the entry of birds into the vent area.
All vents are furnished standard with white or galvalume finish, but are available in special color when specifically ordered.
The base is specifically designed for the final installation, with specified roof slope; either ridge or single slope, and either flat or mounted into customer-furnished roof panel. Base and ventilating unit are furnished pre-assembled ready for installation. Single slope bases are mounted directly into roof panel and are placed in such a way as to prevent damming.
Round gravity roof ventilators are designed for economical, low volume, air movement to ventilate warehouses, light industrial buildings, attics, lofts and other buildings requiring gravity or relief ventilation. They also are adaptable for use as discharge heads for mechanical or forced-air ventilating systems. The volume of gravity air movement can be controlled by the adjustable damper. The damper is also effective in controlling water intrusion from wind driven rain and back draft conditions.
When ordering, please specify roof slope and base type. A wooden crate is included in price.