Permissible Explosives : Explosives approved by the United States Bureau of Mines for use in gaseous or dusty atmospheres; they will not ignite gas and air mixtures and have low sensitivity to impact
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}