EFFECTS OF N₂ AND CF₃Br ON EXTINCTION OF PROPAGATING AND FULLY BURNING FIRES.

Comparisons are made of the effects of a ″physical″ extinguishing agent N//2 and a ″chemical″ extinguishing agent CF//3Br on the burning of PMMA fuel rods. In the first set of experiments, downward propagating fires are investigated in an apparatus similar to that used in making ″Oxygen Index″ measurements. In the second set of experiments, fully burning fires are investigated by a similar technique. Among the experimental findings are that the fully burning configuration is less sensitive to changes in the oxygen concentration than the downward burning configuration and supports combustion at oxygen concentrations below the ″Limiting Oxygen Index.″ The sensitivity to gas phase extinguishing agents is also found to depend upon burning configuration.