The Baker-Strehlow methodology was developed to provide an objective approach to prediction of blast pressures from vapor cloud explosions. The complete methodology was first published in 1994 [1]. Since then, it has evolved through ongoing research and use in VCE hazard analyses, facility siting studies and accident investigations. This article gives a brief overview of a paper on recent developments in the Baker-Strehlow methodology presented at the 31st Loss Prevention Symposium in Houston on March 9-13, 1997. Because the entire paper is too lengthy to be presented here, the following discussions may be lacking in some details. A copy of the complete paper can be obtained from the American Institute of Chemical Engineers (AIChE).

Since the Baker-Strehlow method was first published, it has been used extensively in VCE hazard assessments in refineries and chemical plants. As expected, many practical lessons have been learned during the course of the hazard assessments, and the Baker-Strehlow method has evolved as a result. The changes have been evolutionary, not revolutionary. In keeping with the goals of the original study in which the methodology was developed, all changes have been incorporated with the intent of achieving an objective methodology to provide consistent prediction of VCE blast effects.

The revisions to the Baker-Strehlow method resulting from experience gained during plant walk-downs and hazard assessments include:

  • Systematic identification of “potential explosion sites” or “PESs,”

  • Selection of the level of confinement for mixed zones of 2D and 3D confinement,

  • Deciding on flame expansion when confinement is elevated above the vapor cloud,

  • Selecting the reactivity for a fuel that is a mixture of fuels with differing reactivities,

  • Predicting blast loads when there are multiple PES's within a vapor cloud considering different ignition source locations.