Combustible Gas Indicator 2 : A device that samples air and indicates if there is an explosive mixture present and, if there is, the percentage of the lower explosive limit of the air-gas mixture sampled
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}