Flashover

Uncommon card · No. 196938

A flashover is the near-simultaneous ignition of most of the directly exposed combustible material in an enclosed area. When certain organic materials are heated, they undergo thermal decomposition and release flammable gases. Flashover occurs when the majority of the exposed surfaces in a space are heated to their autoignition temperature and emit flammable gases (see also flash point). A small flame can reach flashover in 3-5 minutes. Flashover normally occurs at between 500 °C (932 °F) and 600 °C (1,112 °F) for ordinary combustibles and an incident heat flux at floor level of 20 kilowatts per square metre (2.5 hp/sq ft). Flashover typically occurs between the growth stage and fully developed stage of a fire. This phenomenon is caused by various heat transfer mechanisms such as radiation, convection, and conduction, which lead to a sudden increase of temperature within the compartment. An example of flashover is the ignition of a piece of furniture in a domestic room. The fire involving...

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