The industrial community has faced many challenges in fire hazard management over its long history. Fire and vapor suppression of flammable and combustible liquids is one challenge we are working through currently.
The primary tool used in industry for the safe response to Class B (flammable and combustible) liquid emergencies in a pooling scenario has been firefighting foam.
The first recorded successful use of firefighting foam to extinguish a Class B fire is from Baku Russia in 1904 on an 11-meter heptane tank (Home Office Fire Research and Development Group, 1991). This first chemical foam required mixing two chemical agents at the time of suppression with difficulty in application. Over the last century, new foam making processes and application methods have prompted the industry to transition our fire suppression systems many times (Jablonski, 1981; Home Office Fire Research and Development Group, 1991; Horst et al., 2021).
We are again at the precipice of transition, moving from a firefighting foam standard with fluorinated components to an alternative that is as effective but without the persistent chemicals found in PFAS (per- and polyfluoroalkyl substances) containing foams.
When I joined the industrial emergency response community in the 1980s, Aqueous Film Forming Foam (AFFF) had a foothold in the industry. I remember keeping large quantities of protein-based foams in our inventories to compensate for the rapid drain times of AFFF foams and to maintain a long-lasting vapor protection after the quick knockdown and extinguishment using AFFF. There were doubters of the efficacy and viability of AFFF in those days across the industry.
Now, as I am approaching the twilight of my career, we have similar issues. New generation Synthetic Fluorine Free Foams (SFFF) are emerging across the globe because of the increasing body of scientific literature and regulatory concern regarding PFAS. While the body of academic and scientific literature continues to grow, this article does not argue one side or the other of the debate about the need to transition from PFAS foams to SFFF (Filipovic et al., 2015; Jonsson, 2017; Boucher, Cousins, Scheringer, Hungerbuhler, & Wang, 2019; Peshoria, Nandini, Tanwar, & Narang, 2020; Horst et al., 2021; Sheng, et al., 2021). This is a practitioner perspective from an end user of firefighting foam. These perspectives are mine alone and not necessarily those of my employer.
I have used firefighting foams in training and real events for over 30 years. During that time, I have witnessed the performance of many manufacturers’ products with a myriad of formulations.
In 2015, the emerging “fluorine free” foams, primarily coming from Europe, were intriguing. I, like many of my colleagues, wanted to better understand the performance of these new foam chemistries and if they are compatible with existing fire suppression infrastructure in the facilities I support.
I am a steering panel member for both the LASTFIRE Project and the NFPA Research Foundation work looking at fluorine free foam performance. My observations have been positive for the progress that the manufacturing community has made in developing high-quality firefighting foams that are certified to be PFAS free. The journey has been a collaboration between end-users, foam and equipment manufacturers, and academics to get to where we are today.
Has synthetic fluorine free foam come of age?
In an article by 3M in the 1970s, the author asked if AFFF had come of age. We have the same question surrounding SFFF formulations today.
There have been thousands of lab-scale, small-scale and standardized performance tests of new SFFF formulations with varying reports and interpretations of those tests. There have been examples of SFFF being used in anger on real events where the SFFF successfully extinguished the Class B emergency (Reisch, 2019; KTVU Digital, 2020).
Still, the question lingers about how SFFF will perform in a large-scale incident with fuel-in-depth.
The LASTFIRE project carried out several tests using a 35-foot diameter tank using both monitor and pourer application in 2016 (LASTFIRE Project, 2018). The project followed these tests with two successful large-scale suppression tests at the DFW International Airport Fire Training Research Center in 2018 that demonstrated the ability of an SFFF to not only extinguish a fuel-in-depth fire but also to travel a greater distance than the “rule of thumb” distances of 60-75 feet in API 2021 (LASTFIRE Project).
The limitations of the temporary testing apparatus built on the training center ground made only a few tests possible. This led the LASTFIRE project to partner with Gesip, a specialist training and testing center in France and build a permanent testing facility at its Vernon, France, location.
The Vernon test facility is a 6-meter-wide by 50-meter-long test pit divided into thirds with overflow weirs. This allows the testing organizers to have a deeper fuel level in the landing zone from either end depending on wind direction. Constructing this facility began in 2019 but experienced several delays because of the global pandemic.
They completed the first formal SFFF testing at this facility over a two-week period in June 2021. The LASTFIRE project facilitators are still working through the data on fuel temperatures, foam qualities, and extinguishing times for an interim report on this phase of testing. Hopefully, LASTFIRE will publish that report by year’s end.
For now, my observations from being part of the project team are:
- 22 different tests completed with six different SFFFs in blinded tests.
- All the tests discharged through commercially available equipment into a “landing zone” area with ~15 CM of fuel depth and ~ 5CM of depth for the rest of the pool.
- Tests were completed with both conventional aspirating and Compressed Air Foam System (CAFS) pourers and monitors.
- One test was successfully completed using a standard combination nozzle with no additional aspiration tube for a semi-aspirated application.
- All tests were at or below the NFPA 11 application rates.
- All tests were successfully completed in less than the NFPA 11 application run time for type 2 and 3 applications.
- All tests used gasoline as the fuel.
Will this round of testing resolve the question of whether SFFF has come of age? Maybe not completely, but it is a good start. The true test of SFFF will come one day when it is used to extinguish an actual tank fire in anger. Until then, the current large-scale testing program being conducted by LASTFIRE will give end-users and manufacturers critical information needed to plan for an eventual transition from PFAS containing foams to a fluorine free option.
The work is not done, we still must evaluate SFFFs on other fuels, particularly polar solvent fuels. Some initial work on this topic is planned for July and August in Hungary. It is a welcomed observation for this point in time.
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Boucher, J. M., Cousins, I. T., Scheringer, M., Hungerbuhler, K., & Wang, Z. (2019). Toward a comprehensive global emission inventory of C4-C10 perfluoroalkenesulfonic acids (PFSAs) and related precursors: Focus on the life cycle of C6- and C10- based products. Environmental Science & Technology Letters, 6, 1-7. doi:10.1021/acs.estlett.8b00531
Filipovic, M., Woldegiogis, A., K, N., Bibi, M., Lindberg, M., & Osteras, A. (2015). Historical usage of aqueous film forming foam: A case study of the widespread distribution of perfluoroalkyl acids from a military airport to groundwater, lakes, soils and fish. Chemosphere, 39-45. doi:10.1016/j.chemosphere.2014.09.005
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Jablonski, E. J. (1981). Evaluation of three percent aqueous film forming foam (AFFF) concentrates as fire fighting agents. Alexandria, VA: Defense Technical Information Center.
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KTVU Digital. (2020, October 24). No injuries in Richmond tanker truck crash and fire on I-80. Retrieved from Fox 2: KTVU: https://www.ktvu.com/news/tanker-fire-shuts-i-80-in-richmond-prompts-nearby-evacuations
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Yu, X., Jiang, N., Miao, X., Li, F., Wang, J., Zong, R., & Lu, S. (2020). Comparative studies on foam stability, oil-film interaction and fire extinguishing performance for fluorine-free and fluorinated foams. Process Safety and Environmental Protection, 201-215. doi:10.1016/j.psep.2019.11.016
Stephen R. Pepper is the director of Crisis Management for Phillips 66 Company, a diversified energy manufacturing and logistics company. This article represents the author’s personal view and not the position of Phillips 66 Company.