Effect of the addition of triphenylphosphine oxide, hexabromocyclododecane, and ethyl bromide on a CH$_4$/O$_2$/N$_2$ flame at atmospheric pressure

The chemical and thermal structure of a Mache–Hebra burner stabilized premixed rich CH$_4$/O$_2$/N$_2$ flame with additives of vapors of triphenylphosphine oxide [(C$_6$H$_5$)$_3$PO], hexabromocyclododecane (C$_{12}$H$_{18}$Br$_6$), and ethyl bromide (C$_2$H$_5$Br) was studied experimentally using molecular beam mass spectrometry (MBMS) and a microthermocouple method. The concentration profiles of stable and active species, including atoms and free radicals, and flame temperature pro.les were determined at a pressure of 1 atm. A comparison of the experimental and modeling results on the flame structure shows that MBMS is a suitable method for studying the structure of flames stabilized on a Mache–Hebra burner under near-adiabatic conditions. The relative flame inhibition effectiveness of the added compounds is estimated from changes in the peak concentrations of H and OH radicals in the flame and from changes in the flame propagation velocity. The results of the investigation suggest that place of action of the examined flame retardants is the gas phase.