Flashover and insulative protection can be required for different situations. Radiant heat can be so intense that materials can either burn and/or melt. In these cases, a thin Nomex layer of clothing will not be sufficient for protection and the addition of insulation is necessary to reduce (not eliminate) major burns. Even Nomex/PBI turnout gear has limitations in providing protection from intense heat over any period of time. Keeping low in a fire situation can significantly increase your chances of survival even with thermal protection. With a flashover, there is a sudden “explosion” but short duration of actual fire, in this case the Nomex layer will provide protection in that the material will not melt and may provide a limited and temporary amount of thermal protection. However if the flashover results in other materials in close proximity to you, to ignite, where the thermal load increases and is maintained, the thin Nomex layer will be insufficient in providing protection. Keep in mind; you can incur significant burn injuries as much from intense heat (and steam) as from the fire itself.

Pete