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Further variations of smoke density with heat flux
Author(s) -
Edgerley P. G.,
Pettett K.
Publication year - 1980
Publication title -
fire and materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.482
H-Index - 58
eISSN - 1099-1018
pISSN - 0308-0501
DOI - 10.1002/fam.810040210
Subject(s) - heat flux , smoke , drop (telecommunication) , combustion , flux (metallurgy) , materials science , ignition system , autoignition temperature , pyrolysis , thermodynamics , heat of combustion , mechanics , chemistry , heat transfer , physics , metallurgy , organic chemistry , mechanical engineering , engineering
The heat flux in the NBS smoke chamber has been varied from 1.0 to 5.0 W cm −2 in 0.5 W cm −2 steps for some fifteen natural and synthetic materials. These experiments confirm the results given in previous papers for a smaller heat flux range, namely that smoke density varies ove4r the temperature/heat flux range. The extended range studied ensured that a much higher proportion of the materials reached a heat flux at which ignition occurred. As before at this and higher heat fluxes, the experiments were repeated in the flaming mode to ensure better reproducibility. With a few exceptions the general shape of the specific optical density/heat flux plot was similar, with a steep rise to a peak and then a corresponding drop to a low value at high fluxes. At 5 W cm −2 the drop had not been reached in some cases, but it is assumed to occur later by inference from earlier work on a smaller‐scale apparatus at high temperatures. Complex materials can give unusual plots during the transition from pyrolysis to combustion. This is true of certain polymers containing fire retardant when the pyrolysis of the additive can have a separate effect.