Dual Alarm System : An alarm system that sounds a coded alarm at selected locations, and at the same time a continuous alarm signal at all other locations until the system is restored to normal
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}