Aqueous film-forming foams (AFFF) are required to be phased out at all military sites by October 1, 2024, as directed by the National Defense Authorization Act for fiscal year 2020. While a new MIL-SPEC has been released for fluorine-free firefighting (F3) performance, the document does not outline a performance requirement for the foams performance with use of saltwater, polar solvents, or extreme conditions. The study aimed to determine the impact of these efficacy on extinguishment time, burn-back time, and other relevant metrics, as well as assessing the potential benefits and limitations of using these F3 formulations.

Testing of F3 formulation was conducted using a full strength 3% solution delivered to a live fire in a foam tube and non-aspirated delivery. Burnback was determined by the moment a flame was present outside of the inserted burnback pot. A 25% drainage time was determined by an evaluation through experiment design similar to National Fire Protection Association (NFPA) 460 guidelines. Fire testing was done on gasoline at high temperatures (>90 F), gasoline with 20% ethanol added (also at >90), low temperature (<40 F), and saltwater (also at <40). Drainage testing was done in standard NFPA 460 fashion and compared against a modified method where gasoline heated to 50C, or 20% ethanol gasoline were first added to the cylinder. Additional testing was performed where the formulation was prepared with saltwater to determine effect in shipboard use. Limited testing was also performed of formulation that was aged for three-months.

During this project ADA Technologies Inc.’s “Formulation D” was tested in extreme conditions. The formulation contains varying amounts of alkylglucose amide, organosiloxane surfactants, and alkylpolyglucosides (APG). Formulation D was designed after the release of the most recent MIL-SPEC for F3 formulations. This formulation was confined mostly by a maximum viscosity of 400 cp. Formulation D was designed as a modification of a previous formulation, formulation C, by the addition of high viscosity component APG so as to increase the expansion ratio of the formulation and more closely match current MIL-SPEC. Formulation C contains the three components listed above in a 3:6:2 ratio.

Environmental testing indicates that ADA Technologies Inc.’s Formulation exhibits nearly similar performance in saltwater condition, but does have diminished performance on polar fuels. The effect of polar fuels and high temperatures is most clearly seen in diminished burn back time which is also supported by a diminished drainage time.

F3 foams meeting the required fire suppression MIL-SPEC performance standard has been an elusive goal for the DoD and industry for many years. Identifying such formulations would provide a viable, high-performance alternative to perfluorooctane sulfonate/perfluorooctanoic acid-containing AFFF.