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AFFF Replacement

Description:

TECHNOLOGY AREA(S): Materials 

OBJECTIVE: A minimally toxic, fluorine-free firefighting agent functionally equivalent to fluorinated Aqueous Film-Forming Foams (AFFFs) for firefighting applications. 

DESCRIPTION: Fluorinated firefighting agents have proven in practice to be more bane than boom. AFFF based on perfluorooctyl-substituted surfactants was for decades the water-based firefighting agent of choice in military and civilian applications until it was determined that two highly persistent, bioaccumulative compounds—perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS)—formed from decomposition of AFFF and other industrial formulations pose a health risk and display unacceptable toxicity to aquatic index organisms. The shorter-chain homologue now used for firefighting is considered a temporary patch, in anticipation of an environmentally compatible next-generation agent and of adverse findings of toxicity in the C-6 AFFF materials and their by-products. Halons are another class of efficient extinguishants that had subsequently to be replaced, after they were found both to be potent ozone-depleting compounds and to aggravate toxicity in the fire environment. A more-reactive perfluorinated agent recently acquired as a halon replacement has been found to decompose in a fire to aggravate toxicity by generating concentrations of HF many orders of magnitude higher than the value cited by ACGIH as immediately dangerous to life and health (IDLH), and which are also highly corrosive to materials that might otherwise be salvageable. Established mechanisms for extinguishment include cooling the fuel below the ignition temperature, typically with water; isolating the fire from oxygen, as with a blanket of AFFF; separating the combustion process from the fuel source, typically with explosives; interception of reactive intermediates in the combustion chain chemistry, as by Br and Cl radicals from halons; displacement of oxygen with unreactive gases, as with a CO2 extinguisher; or by inertion of the fuel with an inert diluent, as by adding water to hydrazine. Electromagnetic approaches showed interesting phenomena in the lab but were technically infeasible for full-scale open-air applications. Criteria for this topic include that the agent not 1) require handling as a HazMat, 2) be or decompose to generate a material that is or will obviously be regulated under NPDES, and 3) decompose in the fire to generate products that significantly escalate the toxicity of the fire environment or strongly promote corrosion of the burning object(s) or surrounding materiel or enclosures. Final capacity for extinguishment must equal or exceed that of C6 AFFF, and the material must be stable in storage at 150 °F for 25 years. Compatibility with existing equipment is desired but not an absolute requirement. 

PHASE I: Justify a prediction of acceptable mammalian and environmental toxicity of agent and byproducts. Reliably extinguish 3-ft pool fires at 3% concentration within 1.5x volume and time for C6 AFFF. Deliverable is a tech report detailing compositions evaluated, results and conclusions. 

PHASE II: Refine composition to enhance persistence of coverage and local extinguishing capacity, and to achieve extinguishment at 3% concentration in water or less. Demonstrate efficacy on pool fires at AFCEC's Fire Research facilities. Measure mammalian and aquatic toxicity of the agent and its combustion byproducts. 

PHASE III: Establish production capability and develop training for firefighters in delivery of the new agent to achieve best efficacy in firefighting. 

REFERENCES: 

1: Environmental asoects of AFFF and ar-AFFF---Ansul, https://www.ansul.com/en/us/DocMedia/F-200311pdf

2:  D.M. Lemal, Perspective on Fluorocarbon Chemistry, Journal of Organic Chemistry, 2004, vol. 69 (1), pp 1–1

3:  American Wastewater Association, Treatment and Removal of PFCs, www.awwa.org/Portals/0/files/legreg/documents/AWWAPFCFactSheetTreatmentandRemoval.pdf

KEYWORDS: AFFF, Extinguishment, Firefighting, Halon, Perfluorocarbon 

CONTACT(S): 

Joe Wander 

(850) 283-6240 

joseph.wander@us.af.mil 

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