Hydrant Wrench 4 : A special wrench, usually with a pentagonal operating nut, used to turn on hydrants and remove caps from hydrant outlets. See: Hydrant Spanner
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}