Guidelines for determining the probability of ignition of a released flammable mass Complemented by an estimating tool spreadsheet based on a fixed set of chemicals to assist in all siting studies [Guidelines for determining the probability of ignition of a released flammable mass] converts a best guess to a calculated value based on available information and current technology. The text provides a technology based approach to deriving the probability that a flammable mass will find an ignition source and ignite. It offers valuable information in the development of a facilitys Emergency Response Plan