Halon 1301 flame extinction results are discussed for the com bustion of polymethylmethacrylate (PMMA), eight composite materials, and carbon in the gas phase. Two types of combustion and flame extinction experi ments were performed: (1) in the Factory Mutual Research Corporation (FMRC) flammability apparatus (50 kW scale) for PMMA and composite materials, and (2) in the FMRC electrical arc apparatus for carbon in the gas phase. For char forming composite materials, mass transfer from the surface was low, turbulent diffusion flames were not generated, and flame extinction oc curred between 3 to 4.5% of Halon 1301, close to the value reported for the lam inar diffusion flames of polymers. For non-charring PMMA, mass transfer from the surface was high, flames were turbulent, and flame extinction was found at about 6% of Halon 1301, contrary to the accepted value of about 4% for the lam inar diffusion flames of polymers. With Halon 1301 the conditions for flame in stability and extinction for combustion efficiency less than about 0.40, with sig nificant increase in the amounts of products of incomplete combustion (such as CO and hydrocarbon), were in agreement with flame instability and extinction found for fuel-rich conditions inside well-ventilated laminar and turbulent diffusion flames, in ceiling layers of combustion products, in enclosure fires, in ventilation-controlled buoyant diffusion flames of polymers, and for flame ex tinction of heptane flames by water. Experiments in the FMRC electrical arc apparatus showed that in the gas phase combustion of carbon vapors generated in high energy arc, chemical heat release rate and combustion efficiency decreased with increase in Halon 1301. At about 7.5% of Halon 1301, conditions were close to flame extinction and at 9.0%, oxidative pyrolysis of carbon was indicated. Concentrations of Br- and F- ions, generated from the decomposition of Halon 1301, were also measured. Concentration of Br- ions was higher than the concentration of F- ions, al though there are three F atoms and only one Br atom in Halon 1301. There was brown deposit on the walls of the apparatus with extensive corrosion of rubber gaskets, electrical fan, and other components. The techniques discussed in this article appear to be attractive for the assess ment of flame extinguishability and corrosive characteristics of fire suppres sants to replace ozone layer depleting Halons.
Structural Studies on Locally Strained Diffusion Flames. 3rd Report. Analysis on Local Flame Extinction and Reignition Phenomena of Unsteady Strained Flames.
