SPECTROSCOPIC INVESTIGATION OF ATMOSPHERIC-PRESSURE COUNTERFLOW DIFFUSION FLAMES INHIBITED BY HALONS

Infrared spectra of atmospheric-pressure counterflow diffusion flames inhibited by halons (a contraction of halogenated hydrocarbons) and a few of their potential replacements are measured with the use of Fouri er transform spectroscopy. Results are compared to spectra of similar flame systems examined at low pressure. It is shown that, for atmosphe ric pressure counterflow diffusion methane/air flames inhibited by CF3 Br, CF2H2, and CF4, the two major fluorine-containing combustion produ cts are HF and CF2O. A correlation is shown between flame inhibition e fficiency and CF2O formation for atmospheric-pressure counterflow diff usion flames inhibited by these halons. For low-pressure premixed flam es inhibited by CF3Br, HF appears to be the only fluorine-containing c ombustion product, even at relative dopant levels 15 times higher than those capable of extinguishing atmospheric-pressure counterflow diffu sion flames. The results of these experiments illustrate the need for flame inhibitant testing over a wide spectrum of flame conditions, whi le providing further evidence that, for atmospheric-pressure inhibitio n of real fires by halons, CF2O may be a good indicator of inhibitor e fficiency when that inhibition is at least partly accomplished by chem ical scavenging of reactive combustion intermediates.