Comparison F3 MilSpec vs ICAO vs AFFF MilSpec fire tests

This comparison table highlights significant differences between new F3¹, existing MilSpec² and ICAO³, including fire testing mostly on easier Jet A fuel, not gasoline. The new F3 MilSpec¹ is more equivalent to ICAO level B not C, but with important extra testing beyond ICAO requirements³. With slower extinguishments and longer 50ft² pre-burn, should fuel volumes be higher for F3 MilSpec? ICAO uses a special nozzle delivering generally higher foam expansion³ than proprietary nozzles widely used by ARFF Services (typically closer to 5:1 expansion^1,2) tougher to pass than ICAO’s test nozzle nearer 10:1 expansion. 2020 NFPA Research Foundation testing¹⁷ confirmed F3s may require 25-50% higher application using 3-4:1 expansion than 7-8:1 expansion on volatile fuel fires like gasoline (relevant for on-airport car parks, including multi-storey often adjacent to terminal buildings). F3 MilSpec benefits from reduced wind speed and short delay before burn back testing, which does not represent realistic firefighting conditions.

Let’s not be fooled by a wide ambient temperature testing range either, as fire testing is always conducted under the minimum required temperature conditions^1,3 to attain the best results for qualification. Another strong reason for verification testing requirements under hot summer conditions of 40^oC or above, particularly when prevailing temperatures exceed the 38^oC flashpoint of Jet A/A1¹⁸ increasing vaporisation and volatility, so it behaves more like gasoline and is harder to extinguish.