Standard round gravity ventilators are available in 12, 20 and 24 - inch diameter throat sizes. Other sizes, up to 48 inches, are available through special orders. 26 gauge inner and outer bands, rain-shield and base assembly are assembled with 4 pre-formed baffles into a simple yet sturdy ventilating unit.

Design

The design achieves a free un-obstructed flow of ventilation 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 long pull chain. 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, over-spray 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 4X4 bird screen in the opening between the inner band and rain shield to resist the entry of birds into the vent area.
 

The base is specifically designed for the final installation, with specified roof slope; either ridge or single slope and either flat or mounted into a 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.    All vents are furnished standard with white or our galvalume finish, but are available with special color when specifically ordered. Installation is by use of standard formed closures, tape sealant, caulking and fasteners as indicated on standard assembly drawings. 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 relief ventilation. They are also 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 the price.