One of the most common uses of dispersion models is to investigate the potential consequences of relief valve and vent emissions to the atmosphere. The model programs are used to predict the concentrations of toxic and/or flammable materials delivered to grade, the levels of thermal radiation delivered by jet and pool fires, and the overpressures resulting from vapor cloud explosions. The application of most dispersion model program packages to those purposes appear to be very straightforward; however, there are several “traps” that an inexperienced user can fall into. Potential problems related to source descriptions, meteorological specifications, and interpretation of output will be discussed, and simple solutions to each problem will be revealed.

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