Foam Application Rates for High Hazard Flammable Train (HHFT) Fires

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In the recent past, there has been several fire incidents involving High Hazard Flammable Train (HHFT), some with catastrophic impact. Flammable liquid spills in the rail road tank car incidents are hybrid and multidimensional in nature, consisting of surface spills, pooled product, and product absorbed into the rail bed and soil. Class B foams are recommended for vapor suppression and as an extinguishing agent for flammable liquid fires. 

First responders to flammable liquid incidents recognize NFPA 11, Standard for Low-, Medium-, and High Expansion Foam, for its value when calculating foam concentration applications for spills and fires at facilities that refine and storage flammable liquids. Product control and vapor suppression techniques used for rail car flammable liquid incidents may not be as accurate when determining foam concentrate calculations from NFPA 11. Further, the foam application rates may vary for three dimensional, free flowing flammable liquid fires.

Previous HHFT incidents show that foam operations can fall into two different operational environments: (1) offensive operations to control or extinguish fires in the early phases of the incident timeline, and (2) extinguishment of the fire in the later phases of the incident timeline after the size and intensity of the fire have diminished (i.e., equilibrium has occurred). Further it is realized that the actual quantity of Class B foam concentrate used for product control, vapor suppression, and fire extinguishment at HHFT incidents in the later phases of the incident timeline have been substantially less than the “area-based” planning values based upon the NFPA 11 parameters. Once “equilibrium” has been achieved and tank car metals cooled, individual tank cars with breaches and internal fires have been extinguished using as little as eight (8) gallons of Class B foam concentrate per tank car.  

Research goal: The overall goal of the project is to develop a compendium of foam application rates and related fire suppression information on High Hazard Flammable Train (HHFT) fire events and three dimensional, free flowing flammable liquid fire scenarios through a thorough literature review, gathering information from responders and technical response teams, and analysis of published after action reviews. The findings from this project would clarify for the responder community the planning estimates to establish a sustained application of foam during suppression of a flammable liquid fire involving above incidents.

Download the project summary. (PDF)