Fire Shelters Fire shelter training stresses the importance of deploying in an area where there will be no direct flame contact. The gas and smoke are flammable, and if flame enters the shelter through a pinhole or under the edge, the gasses can ignite and cause a flashover. The shelter material continues to burn after the flashover, and damage ranges from small holes in the aluminum outer layer to large holes in the aluminum and fiberglass cloth to total destruction of the shelter.
Similar damage can occur from flames in grass and ground litter or from intense flame fronts.
The limiting factor on the shelter's durability appears to be off-gassing and ignition of the adhesive. The precise temperature or heat flux that causes this is not yet known, but recent test results indicate that the temperature is much lower than previously thought. The ignition inside the shelter causes rapid delamination and flaking of the aluminum foil, but when the heat load outside is reduced, the shelter material stops burning in a matter of seconds. If the intense external heat load continues, offgassing and combustion also continue. Firefighters have survived entrapments in shelters with areas of delamination and missing foil.