Spectroscopic Investigation of Atmospheric-Pressure Counterflow Diffusion Flames Inhibited by Halons

Abstract

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 Fourier transform spectroscopy. Results are compared to spectra of similar flame systems examined at low pressure. It is shown that, for atmospheric-pressure counterflow diffusion methane/air flames inhibited by CF3Br, CF2H2, and CF4, the two major fluorine-containing combustion products are HF and CF2O. A correlation is shown between flame inhibition efficiency and CF2O formation for atmospheric-pressure counterflow diffusion flames inhibited by these halons. For low-pressure premixed flames inhibited by CF3Br, HF appears to be the only fluorine-containing combustion product, even at relative dopant levels 15 times higher than those capable of extinguishing atmospheric-pressure counterflow diffusion flames. The results of these experiments illustrate the need for flame inhibitant testing over a wide spectrum of flame conditions, while providing further evidence that, for atmospheric-pressure inhibition of real fires by halons, CF2O may be a good indicator of inhibitor efficiency when that inhibition is at least partly accomplished by chemical scavenging of reactive combustion intermediates.

The features of combustion of hydrogen and methane in oxygen and air in the presence of difluorodichloromethane additives

“…HCl was not detected. FTIR data [25] of the products of CH 4 + O 2 + CF 3 Br allow identifying HF (v = 0), CF 4 , COF 2 , H 2 O and CO 2 . HBr bands are very weak, i.e.…”

Diode Laser Measurements of HF Concentrations From Heptane/Air Pan Fires Extinguished by FE-36 and FE-36 Plus APP

“…These fluorinated propanes, though effective at extinguishing fires, are deficient in terms of increased weight and volume requirements needed for fighting the most difficult military fires. The increased amounts of replacement agent required for extinguishment, relative to halons 1301 and 1211, pose a concern with the levels of hydrogen fluoride (HF) formed as the primary decomposition product [1]. This concern has limited the acceptance of these agents for deployment in occupied spaces.…”

Diode Laser Measurements of HF Concentrations Produced from Heptane/Air Pan Fires Extinguished by FE-36, FM-200, FE-36 Plus APP, and FM-200 Plus APP

“…The increased amounts of replacement agent required for extinguishment, relative to Halons 1301 and 1211, pose a concern with the levels of HF formed as the primary decomposition product. Thus, the tests presented here measure the concentration of gas-phase hydrogen fluoride (HF) using near-infrared (NIR) tunable diode laser absorption spectroscopy (TDLAS) [1]. A recent article from this laboratory details the use of NIR-TDLAS as the most effective diagnostic for gas-phase HF measurements [2] Figure 1 shows a schematic diagram of the test facility containing the NIR-TDLAS experimental apparatus and signal-processing electronics.…”