Previous work on the interrelations of the flammability properties of n-alkanes in air have been extended to both vapor and liquid fuel mixtures. Based on the application of Raoult's and Dalton's laws governing vapor pressure and composition above a solution of two or more liquid hydrocarbons to Le Chatelier's rule governing the flammability limits of vapor mixtures, equations have been derived which make it possible to predict overall flammability properties of mixtures from the properties and proportions of the individual components. The flammability properties which were studied include: lower and upper flammability limits, heat of combustion, stoichiometric concentration, flash point, and flammability index ('explosiveness'). The derived equations demonstrate, quantitatively, why vapor pressure of individual constituents plays a more important role than concentration on the overall flammability properties of liquid hydrocarbon solutions, and that a very small amount of a highly volatile contaminant in a relatively nonflammable fuel may make it flammable. (Author).

It was demonstrated by a simplified treatment that vapor pressures of individual constituents play a more important role than concentration on the overall flammability properties of hydrocarbon mixtures. This treatment is based on the application of Raoult's and Dalton's laws governing vapor pressure and composition above a solution of two or more liquid hydrocarbons to Le Chatelier's rule governing the flammability of vapor mixtures. The most important conclusion demonstrated by the derived equations is that a very small amount of highly volatile contaminant in a relatively nonflammable fuel may make it flammable. The amounts needed can be predicted from the equations and the properties of the components. Although precise relationships have been derived only for relatively simple solutions of pure hydrocarbons, the concepts they imply are applicable to more complex mixtures such as jet and diesel fuels. The flammability properties included in this study are lower and upper flammability limits, flash points, and flammability indices of liquid solutions. (Author).