Flash point of flammable binary mixtures: Synergistic behavior

In this work, the effects of intermolecular forces on Flash Point (FP) of various binary mixtures have been quantified through calculations taking into account their non-ideality. It has been shown that highly non-ideal mixtures with low-boiling azeotrope may have values of the FP lower than the lowest value of FP between those of the pure components. This behavior has been quantitatively linked to the activity coefficients showing that, when they are significantly higher than unity, a synergistic behavior arises strongly lowering the FP of the mixtures. All results were collected in a safety map that represents a starting point for risk evaluation. In conclusion, in the case of non-ideal mixtures with low-boiling azeotrope, from a safety point of view, measurements of the FP at different liquid compositions and/or calculations with reliable models are absolutely necessary, given that the lowest value of FP between those of the pure substances cannot be considered as the most conservative value.