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Chemical flame inhibition using molecular beam mass spectrometry bromotrifluoromethane in low pressure methane--oxygen--argon flames

Technical Report ·
OSTI ID:5311041
A molecular beam-mass spectrometer-low pressure flat flame apparatus has been constructed for the purpose of examining the chemical microstructure of normal methane-oxygen-argon flames and those inhibited with Halon extinguishants. Details of construction and performance of this apparatus and of related flame temperature measurements are given. Particular attention is paid to the empirical characterization of the perturbation to the flame caused by the sampling probes. The composition profiles obtained for normal flames are compared to those of flames inhibited by CF/sub 3/Br. In addition to the usual stable species (CH/sub 4/, O/sub 2/, CO, CO/sub 2/, H/sub 2/O, H/sub 2/, and H/sub 2/CO), the inhibitor, its products and intermediates associated with its reactions could be followed; in particular, hydrogen bromide, bromine atoms, hydrogen fluoride, and carbonyl fluoride were observed. The relatively rapid disappearance of inhibitor and early appearance of fluorinated reaction products suggest a short lifetime for the CF/sub 3/ radical in this system. Observation of COF/sub 2/ suggests that CF/sub 3/Br is effective as an inhibitor, at least in part, by virtue of its interference with the oxygen containing species of the normal chain reaction. Profiles of the 17/sup +/ peak at low electron energy suggests that the hydroxyl radical may also be sampled, but the profiles obtained are not yet sufficiently accurate to determine the effect of inhibitor on this important flame radical.
Research Organization:
Bureau of Mines, Washington, D.C. (USA)
OSTI ID:
5311041
Report Number(s):
BM-RI-7723
Country of Publication:
United States
Language:
English