Lower and Upper Flash Points of Flammable Liquids with Flame-Suppressing Agents

Abstract

The lower and the upper flash points of mixtures containing non-flammable liquids were measured by a modified Seta-flash closed-cup tester. The shape of the concentration-temperature region of flash depended on the components of the mixture in solution. Concentration regions for a flash were calculated from the temperature regions of flash and compared to the flammability diagram. We present a theoretical method for calculating both the lower and upper flash points by liquid mixture thermodynamics, and the flammability diagram. The experimental values for the methanol/water mixture agreed with calculated values, but disagreed for halogenated hydrocarbon mixtures. The difference be tween the calculated and experimental values is from a flame-suppressing effect in the gas phase, which is distinct from the thermodynamic effect on solution. We discuss the magnitude of this flame-suppressing effect exhibited by halogenated hydrocarbons in the gas phase.