Chris Schultz
November 18, 2011
[Full Marks JCB]

OF SUBSTANCES AND MIXTURES by M. Hristova, S. Tchaoushev

The flashpoint of a liquid is the lowest temperature at which the vapor can form an ignitable when dispersed in air. Flammability is an important safety concern, and flash points help to determine shipping, packaging, and other safety regulations of materials. There is often a lack of experimental data about flash points of materials, so methods of predicting flash points is important. There is already a reliable method to find the flash point of pure hydrocarbons. A correlation was developed to find flash points of organic compounds petroleum functions, this correlation showed to have incredibly high accuracy when compared to experimental data. Several other equations have been derived and developed to help predict the flashpoint of materials without performing experimental data. The relationship of ideal vapors and non ideal liquids can be used to help predict flash points. Affens and Mclaren developed a useful method for trying to find the flashpoint of vapors that works well with hydrocarbons. Wickey and Chittenden developed a method using flash point indices and volume fractions to find the flash points of petroleum mixtures. Flammability limits are the range of concentration of a gas where it will still be flammable, the upper limit causing oxygen to be insufficient for flame, and the lower range with too little gas in the air for a flame to continue. Equations have been developed to find flammability limits. Heat of oxidation can be sued to help find the flammability limits for the lower bound even when not at standard pressure. Almost all estimates of flashpointsa re in some way based off of Le Chatelier’s Principles, and so may not hold true at high temperature and pressure. Some methods may lead to erroneous data in chemistry databases as they require knowledge of flash points of all components of a material. The close relation between boiling points and flash points are only valid at the specific parameters they are developed at.
This paper stressed the safety importance of knowing flash point values. It went on to explain some of the ways that flash points may be calculated without performing experiments. The paper went on to explain how current methods of finding flash points without using experimental data tend to be inconsistent at high temperature and pressure.