Air Foam Concentrate : A liquid which, depending upon its concentration and nature, is used in proportions of 3 per-cent to 6 percent in water to produce foam
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}