Scenarios and Probability Assignments

The literature indicates numerous, often widely different values for assigning probabilities to scenarios such as those of Figs. 10.2, 10.3 and 10.4. This reflects uncertainties due to lack of knowledge (epistemic) and stochastic (aleatory) effects. If properly treated these uncertainties should be represented by probability distributions. Table 10.15 gives an overview of conditional probabilities for the consequences of a puff release of a pressurized flammable gas from various sources. Not only are the differences in probabilities evident but also the differences as to the endpoints. 

In what follows mainly results from [10] are used. These relationships and numerical values were obtained in a project carried out by the Explosion Research Cooperative , a consortium of chemical companies. The relationships 

Source Immediate (instantaneous) ignition Delayed ignition Flash fire Fireball No ignition Endpoints considered 

Ref [76] 0.1 0.2 0.67 0.72 Elash fire Explosion Jet fire Dispersion without ignition 

Ref [77] 0.4 0.12 0.8 0.4 0.88 Eireball Elash fire Explosion Dispersion without ignition 

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