Chemistry of Fire

This chapter is organized into three main sections providing discussions on the chemistry of fire and explosion, and the chemistry of hazardous materials. The last section of this chapter provides the reader with an extensive glossary of technical terms dealing with chemical hazards and hazard materials handling. 

Fire and Explosion Hazards Handbook of Industrial Chemicals 

An analogous series of hydrocarbons, and one of the simplest, are the compounds known as the alkanes. In this series, the names of all the compounds end in -ane. The first compound in this series is methane. Methane s molecular formula is CH4. Methane is a gas and is the principal ingredient in the mixture of gases known as natural gas. The next compound is this series is ethane, whose molecular formula is C2Hfi. It is also a gas present in natural gas, although in a much lower percentage than methane. The difference in the molecular formulas of methane and ethane is one carbon and two hydrogen atoms. 

Propane is the next hydrocarbon in this series, and its molecular formula is C3H8 which is one carbon and two hydrogen atoms different from ethane. Propane is an easily liquified gas which is used as fuel. 

The next hydrocarbon in the series is butane, another rather easily liquified gas used as a fuel. Together, butane and propane are known as the LP (liquified petroleum) gases. Butane s molecular formula is C4HI0, which is CH2 bigger than propane. 

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The assessment of the contribution of a product to the fire severity and the resulting hazard to people and property combines appropriate product flammabihty data, descriptions of the building and occupants, and computer software that includes the dynamics and chemistry of fires. This type of assessment offers benefits not available from stand-alone test methods quantitative appraisal of the incremental impact on fire safety of changes in a product appraisal of the use of a given material in a number of products and appraisal of the differing impacts of a product in different buildings and occupancies. One method, HAZARD I (11), has been used to determine that several commonly used fire-retardant—polymer systems reduced the overall fire hazard compared to similar nonfire retarded formulations (12). 

There are three basic theories that are used to describe the reaction known as fire. They are the fire triangle, the tetrahedron of fire, and the life cycle of fire. Of the three, the first is the oldest and best known, the second is accepted as more fully explaining the chemistry of fire, while the third is a more detailed version of the fire triangle. Each is briefly described below. 

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