Assessing genuine flammability hazard of halogenated species for their safe processing and use: Case studies

International audienceIt is recognized that the combustion of halogenated substances (gas and liquids) may present specific features compared to traditional hydrocarbons. As a matter of facts, the standardized flammability characterization methods referenced by the various regulations (transport, labeling, etc.) do not necessarily take the specific features of these substances into account. Subsequently, this may lead to an underestimation of the risk associated with their use (physical hazard such as explosion). Through two case studies of interest, one concerning a fluorinated liquid, the other focusing on a fluorinated gas, this work reveals technical difficulties that may arise in appraising actual flammability hazards of halogenated hydrocarbons, due to their combustion specific behavior, when applying existing flammability methods without appropriate expert judgement. In the case of the liquid ethoxy-nonafluorobutane (Novec 7200™) this work highlights that this substance can be erroneously considered non-flammable due a clear pitfall of flash point methods, whilst its genuine flammability can be revealed otherwise. Regarding gaseous halogenated species, we show that operating conditions shall be carefully selected to reveal the genuine flammability behavior of such substances. Indeed, this is not necessarily correctly identified in all possible flammability hazard rating standard methods. In this study, the application of European standards allows to confirm that R1234ze(E) is flammable at temperatures below 30 °C, at atmospheric pressure and at a humidity of 50%RH