Materials flammability development, fire test ignition

Higher irradiation levels give better reproducibility, more clearly defined ignition, and shorter measurement times, but correspond to more developed fires. Thus particularly for flame-retarded polymers, a smaller irradiation level often corresponds better to the fire protection goals addressed. Cone calorimeter results for the HRR at small irradiances correspond to flammability tests such as LOI and UL 94, if a reasonable set of materials are compared and the behavior is not dominated by dripping effects. Thus different considerations govern the choice of external heat flux.76 77... 

Fire testing and classification of building and other materials are based on certain flammability characteristics such as flame spread, ignition temperature, smoke development, non-combustibility, fire resistance, rate of heat release, oxygen index, etc. Some of them are briefly discussed in the following paragraphs [124-126]. 

At present there is no small-scale test for predicting whether or how fast a fire will spread on a wall made of flammable or semiflammable (fire-retardant) material. The principal elements of the problem include pyrolysis of solids char-layer buildup buoyant, convective, tmbulent-boundary-layer heat transfer soot formation in the flame radiative emission from the sooty flame and the transient natme of the process (char buildup, fuel burnout, preheating of areas not yet ignited). Efforts are needed to develop computer models for these effects and to develop appropriate small-scale tests. 

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