The flash point and the boiling point are the regulatory-driven criteria (as referred to in the Globally Harmonized System of Classification and Labelling of Chemicals, known as GHS) on which the classification for the flammability of liquids shall be based in all classification systems of hazardous materials. Some liquids or mixtures of liquids do not have a flash point but can nevertheless generate explosive atmospheres (ATEX). For halogenated liquids, flammability is not necessarily correctly evaluated by use of flash point measurement methods, all based on very small test vessels, sometimes leading to "false negatives" results (no flash detected).The alternative way to solve the flash point issue is the measurement of the Lower Explosion Point (LEP) (also call lower temperature limit of flammability) or the lower explosive limits (LEL). This paper reports on an experimental work to illustrate the issue, by a case study focusing on ethoxy-nonafluorobutane (a fluorinated degreasing solvent whose flash point is non-existent according to published material safety data sheets and therefore classified as ‘non-flammable’ according to CLP). However, real flammability of this substance is shown by use of European standard methods for the determination of the LEP and the LEL.
