Visual Alarm System : An alarm system which uses visual means instead of or in addition to audible means to alert the occupants of a fire; it is common in buildings where deaf persons are present
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}