Heavy Stream : Any fire fighting hose stream, usually delivered through a fixed nozzle with a large-diameter tip, exceeding 400 gpm or having a nozzle diameter greater than 1-1/4 in. See: Master Stream.
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}