Although foam is the main extinguishing agent used in fighting
aircraft crash fires, subsidiary agents are often carried to
extinguish fires in enclosed or obstructed spaces, such as engine
nacelles, where forun cannot readily be applied. In addition, such
agents are often required for rendering inert the atmosphere within
wing spaces, where the rupture of fuel tanks or fuel lines would
otherwise give a risk of explosion or fire.
Carbon dioxide is the most widely-used subsidiary agent, but dry
powders and chlorobromomethane have been suggested as alternatives.
In this note, an estimate is made of the relative vaIues of the three
agents for inerting confined spaces, based upon available information
of their properties.
