The Department of Defense’s (DoD) goal was to eliminate fluorinated compounds from firefighting formulations as soon as possible. Towards this end, projects were sought to demonstrate and validate more environmentally sustainable (fluorine-free) fire suppression alternatives against the current performance requirements outlined in MIL-PRF-24385F (SH) with interim amendment 3. The intent of this solicitation was to determine the maximum available performance using mature fluorine-free firefighting agents against the current military requirements and uses. The following considerations were of interest:
Demonstration of fluorine-free fire suppression agents that can be utilized with the delivery mechanisms and rates specified in the current performance requirements noted above.
Demonstration of fluorine-free fire suppression agents that utilize alternative delivery mechanisms or rates, but still meet other critical performance criteria. Of particular interest is examination of fluorine-free fire suppression agent compatibility with both aspirated and non-aspirated delivery methods.
Evaluation of current test methodologies in MIL-PRF-24385F to determine minimum performance requirements needed to mitigate fires in operational environments or development of novel test methodologies for screening firefighting formulations for liquid pool fires.
Evaluation of the impact that elevated ambient air temperatures have on the fire performance of fluorine-free firefighting agents and reference MILSPEC qualified AFFFs in order to address known concerns on the effectiveness of firefighting agents in equatorial environments.
Due to the expense of large scale testing, only fluorine-free fire suppression alternatives that demonstrated promise based on initial small scale testing (28 ft2 and 50 ft2 tests of the current MILSPEC) were of interest for large scale demonstrations. Information on the historical 1260 ft2 pool fire test is available in Section 18.104.22.168 of MIL-F-24385B.
The materials and processes to be demonstrated/validated should have already been developed to at least a Technology Readiness Level (TRL) of 4, and the proposed project should have brought them to TRL 7 or higher. Alternative formulations should have been production level materials rather than laboratory batch level samples. Projects were asked to demonstrate producibility, defined as the ability to be produced in the near term to meet the current DoD airfield or shipboard use requirement.
Field testing in military relevant environments should have been included in the proposed project. Alternative formulations should have been compatible with generally used storage equipment (e.g., polyethylene) and piping (steel, copper-nickel, bronze alloys), while providing comparable corrosion rates to current AFFF. Formulations should have met requirements with fresh and salt water at multiple delivered concentrations. In addition, formulation stability should have been demonstrated. Proposals could have include approaches to demonstrate similar correlation between large and small scale fire tests with fluorine-free fire suppression alternatives, in lieu of large scale tests.
Proposals should have included an assessment of the human health and environmental impacts of proposed ingredients, formulations, and byproducts. This should have expanded on commonly used aquatic toxicity, chemical oxygen demand and biodegradability testing required in the MIL-PRF- 24385F. These proposals should have established a baseline lifecycle framework and identified the lifecycle inventory elements currently known, those to be investigated during the project, and those beyond the scope of the proposed work.
All projects should have involved at least one DoD organization as a funded co-performer that was considered a stakeholder for the intended application. Proposals should have also indicated the involvement of other DoD stakeholders at the consultant level and higher.
Funded projects will appear below as project overviews are posted to the website.
AFFF is a water-based foam used by the military since the 1970s for fire suppression in ships, shore fixed systems, aircraft hangars, and to extinguish liquid fuel fires. AFFF mixtures containing significant quantities of perfluorooctane sulfonate (PFOS) and related perfluoroalkyl sulfonates were in use until 2002, when production stopped; however, the DoD continued to use PFOScontaining AFFF stocks for some time after the halt in production. It is estimated that there are still over 500,000 gallons of PFOS-based AFFF in stock in the DoD inventory. The Air Force and Navy are the primary users for AFFF, with an estimated current stockpile of 423,000 and 97,000 gallons, respectively.
New AFFF formulations with telomer-based, short-chain fluorosurfactants (C6 or shorter) have been shown to have a reduced environmental impact. However, these materials still have the potential to persist in the environment or even to contain trace quantities of PFOS or PFOA. The current specification, MIL-PRF-24385F (SH) w/ interim amendment 3, does not require the presence of a fluorocarbon surfactant, and sets a maximum allowable content for perfluorooctanoic acid (PFOA) and PFOS. Current regulations for the short-chain compounds are less strict, but it is uncertain what the long-term environmental remediation requirements may be for these materials.
Since 2006, use of AFFF containing PFOS and PFOA has generally been replaced by foams that have fluorosurfactants of 6 carbons or fewer. These newer foams are thought to be less toxic and biopersistant and bioaccumulative, though concerns remain.
At this time, AFFFs used by the military may contain fluorinated surfactants (and other compounds) per MIL-PRF-24385F w/ interim amendment 3. Early revisions of MIL-PRF-24385 included a large scale (1260ft2 ) pool fire test which was eventually eliminated after testing demonstrated positive correlation between large and small scale fire test results.
Industry has identified potential fluorine-free alternative foams; however, none of these technologies meet the fire performance or intercompatability required for military applications. MIL-PRF-24385 requires DoD to evaluate AFFF for foamability and sealability using specific test conditions (nozzles and application rate) to meet specific fire extinguishment and burn back times. Many fluorine-free alternatives can be used to extinguish pool fires, but do not meet the strict requirements outlined in MIL-PRF-24385F (SH) w/ interim amendment 3.
This problem is not unique to military operations. Civil aviation continues to use AFFF or fluorosurfactant-free fire suppression foams that do not meet the performance of AFFF. Alternatives that meet or exceed current AFFF performance requirements without fluorosurfactants would dramatically reduce the environmental impact of fire suppression training and operations while maintaining the safety of personnel at crash sites or around liquid poolfires.