Archive for September, 2012

by: Jason A. Sutula

As a fire investigator, it is our duty to obtain as much information related to the fire incident as possible so that an appropriate analysis of the origin of the fire, cause of the fire, and responsibility for the fire can be completed. In any given fire, the most significant factor affecting the ability of occupants to escape when remote from the room of origin is carbon monoxide. Carbon monoxide is a product of combustion that is formed in very large quantities after a room within a structure achieves full-involvement. Carbon monoxide in sufficient concentrations will cause the incapacitation of victims followed by death. Thus, obtaining autopsy reports and medical data on fire victims is critical in conducting a thorough origin and cause analysis.

This topic and many others will be discussed and presented at the upcoming International Symposium on Fire Investigation Science and Technology (ISFI 2012, October 15-17) taking place at the University of Maryland in College Park, MD. I will be presenting a paper related to the uptake of carbon monoxide by fire victims titled “Methodology for Linking Carbon Monoxide Uptake in Fire Victims with Computer Fire Modeling in Post-Fire Reconstruction Analyses.” The abstract for this paper is presented below, and, after the conference is completed, I will provide a summary of the article in a separate post.

ABSTRACT

The use of computer fire modeling in post-fire reconstruction analyses has continued to increase in both use and significance. It is now commonplace to find computer fire modeling used in both investigative and research settings for the comparison of competing fire initiation scenarios, detector and sprinkler activation, fire growth and spread, and the transport of toxic products of combustion. In particular, the use of a zone modeling code such as the Consolidated Model of Fire and Smoke Transport (CFAST) or a Computational Fluid Dynamics (CFD) code such as the Fire Dynamics Simulator (FDS) has become the norm when analyzing the most complicated and complex fire losses.

The most tragic of all fire losses are those where a fire fatality has occurred. These fire losses naturally tend to be the more complicated and complex to analyze. One of the most important factors to consider in this type of fire loss is whether or not the victim died as a result of carbon monoxide. Carbon monoxide is, arguably, the most significant factor affecting the ability of occupants to escape when remote from the room of origin. As a product of combustion, carbon monoxide is formed in very large quantities after flashover has occurred during a fire event. Carbon monoxide will combine readily with hemoglobin in the blood of a fire victim to form carboxyhemoglobin (COHb), which in sufficient levels will cause incapacitation (i.e., the loss of consciousness and the inability to move), followed by death. The most commonly used model for the prediction of carbon monoxide uptake in humans is the Coburn, Forster, Kane Equation (i.e., CFK Equation).

Currently, neither zone modeling codes nor FDS provide a means for assessing the effects on fire victims of carbon monoxide uptake. A user is able to predict the production and transport of the toxic gas throughout the model space, but further analysis must be completed in the post-processing of the model results.

This paper proposes a methodology for linking a carbon monoxide uptake analysis for victims of a fire with computer fire modeling. First, a standardized methodology for bridging the gap between data generated by computer fire modeling predictions and the use of those results for the analysis of carbon monoxide uptake in fire victims will be presented. Second, a case example of a post-fire reconstruction analysis utilizing the methodology will be explored.

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