Smoke Vent 3 : An opening installed in a roof ranging from 16 sq ft to 100 sq ft; it usually has a lightweight metal frame and housing and a hinged damper which is opened manually or automatically in the event of fire
Ralph W. Burklin & Robert G. Purington, Fire Terms: A Guide to Their Meaning and Use, National Protection Association, Boston, MA 1980 USA. (Guide: Meaning and Use, Nat Prot Association Fr Srvc - Amer) {457}