An influence of oxygen content in an oxidizing atmosphere on inhibitive action of fluorinated agents on a hydrogen flame

An experimental investigation of the influence of inhibitors of various chemical natures on flammability limits in mixtures H2+oxidizer (O2+N2)–suppressant (C2HF5; CHF3; C4F10; inhibitor AKM, which is a mixture of olefins) was carried out. Compositions of N2 and O2 with elevated (25 vol%) and reduced (15 vol%) oxygen concentrations and air were used as oxidizing atmospheres. Experiments were done at room temperature and atmospheric pressure. Flammability limits were determined in a closed vessel of volume of 4.2 dm3 (internal diameter 20 cm). Mixtures were prepared immediately in the preliminary evacuated reaction vessel by partial pressures. The mixtures were ignited by an electrical spark of energy near 1 J in the center of the reaction vessel. A flame propagation was detected by a pressure transducer. Twelve flammability curves were measured, which allowed to compare effectiveness of the inhibitors at various oxygen contents in the atmosphere. A qualitative analysis of the obtained results was done, which showed an important role of an inhibitor regeneration.