Fire incidents involving flammable liquids have historically resulted in dire consequences. Incidents can occur in aircraft hangars, shipboard spaces, flammable liquids fueling facilities, large fuel storage tanks, and other settings and can range from small, short spill fires to large tank farm fires which can burn for multiple days. A prominent example of the latter is the Intercontinental Terminals Company Deer Park petrochemical facility fire in Texas in March 2019. That fire started on March 17 and was finally brought under control on March 23.
Class B firefighting foams are the primary agents used for the vapor suppression and extinguishment of flammable liquid fires in both manual and fixed system applications. Firefighting foams form a film and/or a blanket of bubbles on the surface of flammable liquids and prevent the fuel vapors and oxygen from interacting and creating a flammable mixture.
For nearly five decades, Aqueous Film Forming Foams (AFFF) have been used as the dominant and effective Class B firefighting foam. Prior to the adoption of AFFF, the primary agent for flammable liquid firefighting was Protein Foams, which are derived from the hydrolysis of protein products and then delivered as aspirated foam to produce a smothering blanket of foam bubbles on the fuel surface. AFFF contains fluorosurfactants (per- and poly- fluoroalkyl substances [PFAS]) that provide the essential characteristics of fuel repellency, heat stability, low surface tension, and positive spreading coefficient so that an aqueous film formation can be formed on the fuel surface. AFFF has traditionally been recognized for its effective fire control characteristics. However, today these foams are now of significant concern in light of potential adverse health and environmental impact.
The potential environmental, safety and occupational health risks associated with the use of fluorosurfactants such as some PFAS present in AFFFs started to become evident to the scientific community in the early 2000s. The unique chemical nature of the carbon-fluorine bond in PFAS make some of these compounds persistent, bio accumulative, toxic and have emerged as “contaminants of concern” as considered by the EPA. As a result, the ability to use AFFF to extinguish Class B fires continues to be greatly restricted due to bans in numerous States in the United States and in countries across the world such as Australia. Recently, Federal and State authorities have implemented health and environmental regulatory actions for PFAS and PFAS-containing AFFF. These regulations will ultimately impact, if not eliminate the production, distribution, and use of legacy AFFF in upcoming years.
As more regulations come into place to address this issue, fire departments and other industrial end users are seeking AFFF replacements. In the meantime, the capabilities and limitations of the replacement foams and agents are continuing to be investigated through various research and testing programs to better understand their characteristics and effectiveness for various applications.
The Fire Protection Research Foundation (FPRF), the research affiliate of NFPA, facilitated a research testing program (2018-20) to evaluate the fire protection performance and effectiveness of multiple fluorine free Class B firefighting foams on fires involving hydrocarbon and alcohol fuels. This study provided guidance to inform the foam system application standard, i.e., NFPA 11, Standard for Low−, Medium−, and High− Expansion Foam based on the testing conducted at the time of this research, and identified knowledge gaps and research needs so that we can better understand the capabilities and limitations of fluorine free foams. Additionally, there are multiple other ongoing research efforts. There are research programs led by the US Department of Defense’s SERDP and ESTCP underway, including testing on the development of PFAS-free firefighting formulations, studying the fire suppression performance and ecotoxicology of these formulations as well as the cleaning technologies for firefighting equipment.
LASTFIRE (Large Atmospheric Storage Tank Fires), an international industrial end user consortium, has also been focusing on the selection and use of firefighting foams for large storage tank applications. Additionally, the Firefighter Cancer Cohort Study is developing a national framework to collect and integrate firefighter epidemiologic surveys, biomarkers, and exposure data focused on carcinogenic exposures and health effects. Part of the long-term cohort study will look at the health effects of firefighters that have been routinely exposed to firefighting foams during their activities and careers.
Clearly, this is a complex problem, with concerns that include fire control/extinguishing performance, health exposure, and environmental contamination. And for the fire service, challenging Class B flammable liquid fires are not going away and must be addressed. The learning from these ongoing studies have been promising and demonstrate a step in the right direction to develop a full understanding of this complex problem so that we can transition to firefighting foams of the future without experiencing “substitution regret” (i.e., to avoid multiple repeated replacements over time).
The Fire Protection Research Foundation recently published the report titled “Firefighting Foams: Fire Service Roadmap.” This project was initiated with the funding support from FEMA Assistance to Firefighters Grant (AFG) program, with an overall goal to provide guidance to the fire service community by developing a roadmap to transition from AFFFs to a suitable, environmentally friendly, non-toxic, and effective alternative. The roadmap document is based on the information available at the time of the program. The roadmap and associated documentation have been assembled in a systematic path that covers current regulations, considerations for transitioning to replacement foam, cleaning of equipment and disposal of effluents and legacy concentrates, foam selection and implementation considerations, minimizing firefighter exposures, and ways to handle foam discharged from a cleanup and documentation perspective.
A key element of this project entailed a three-day virtual workshop hosted by the FPRF late last year, October 2021. Subject matter experts delivered 28 presentations on the state of knowledge and related issues. If you missed this FPRF workshop, please visit the project website for workshop presentations, and final proceedings.
Did you know the Research Foundation is celebrating its 40th year in existence in 2022? Learn more about this noteworthy milestone at www.nfpa.org/fprf40.