Estimating flame speeds for use with the BST blast curves



The Baker-Strehlow-Tang (BST) vapor cloud explosion model is one of the most common methods used to estimate overpressures for the purpose of locating buildings in relation to process units. This model suffers from a problem common to all simplified explosion models: the user is required to pick the “strength” of the explosion using one or more simple parameters. In the BST model, the fuel reactivity, flame expansion, and obstacle density parameters are used to select a flame speed from a limited matrix of possible values. This article presents the Quest Model for estimation of flame speeds (QMEFS), a systematic approach to estimating flame speed that does not rely on the BST categories. It provides for a continuous range of flame speeds that can then be used with the existing BST blast curves to calculate the characteristics of the vapor cloud explosion. The QMEFS approach provides the user with a method for describing a vapor cloud explosion that is more detailed than the BST model, and establishes a more refined system for predicting the consequences of vapor cloud explosions. © 2008 American Institute of Chemical Engineers Process Saf Prog, 2009