METHODS FOR VAPOR CLOUD EXPLOSION BLAST MODELING

The potential explosion hazard of fuels is quantified by methods in which the explosive potential of a flammable fuel air mixture is expressed as an equivalent explosive charge whose blast characteristics are known. In this paper, the two most current methods are described and demonstrated in a simple case study. TNT-equivalency methods have been widely used for this purpose for a long time now. Generally speaking, TNT-equivalency methods state a proportional relationship between the quantity of fuel available and the weight of a TNT charge expressing the cloud's explosive potential. However, fundamental and practical objections are met if the TNT-equivalency concept is used for vapour cloud explosion hazard assessment. To some extent, these difficulties are remedied in an alternative approach, the multi-energy method. In the multi-energy method, a flammable fuel air mixture is considered to be explosive only if it is in a partially confined, congested or obstructed area in the cloud. The explosive potential of the fuel air mixture in the various partially confined, congested or obstructed regions can be expressed as a corresponding number of equivalent fuel air charges. The multi-energy concept is shown to be a flexible concept which makes it possible to incorporate current experimental data and advanced computational methods into the procedure of vapour cloud explosion hazard analysis.