Ring Main Brit : A looped water main connected to one or more street mains and around buildings or fire risks, that supplies hydrants, risers, sprinklers, etc
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}