It would be more accurate to say that it prevents the fuel from decomposing into a oxidizable form. Almost everything that will burn has to be turned into a gaseous state before it can be oxidized in a combustion reaction. It is the heat side of the fire triangle that accomplishes that gassafiction and chemical breakdown of the fuel into the unstable fractions; called free radicals by chemists; that will readily oxidize in the combustion reaction that is colloquially called fire. So products like coldfire reduce the fuel temperature below it's ignition point which is the temperature at which it will give off flamable gas.
Foam and CO2 are the extinguishing agents that actually separate the fuel from the oxegen. CO2 does this by being heavier than air and thus pushing the oxygen containing air away from the combustion zone. Foam does it by inserting a vapor suppressing blanket between the fuel and the air and by also cooling the fuel to the point were it will not give off as much flammable vapor. Keep in mind that flammable liquids give off flammable vapors at normal ambient temperature and pressure. That is why straight cooling will not work to extinguish a flammable liquid fire. Applying water as a fog or fine mist caused the water to flash into steam which smothers the fire by displacing the air. Water expands to 1700 times its liquid volume when it is converted to steam.


Tom Horne