Aqueous film-forming foams (AFFF) used by the military for fire suppression contain per- and polyfluoroalkyl substance (PFAS) that are hazardous to human health and the environment. In response, the 2020 National Defense Authorization Act prohibits use of fluorinated AFFF on military installations by 2024. It also requires that the Department of Defense (DoD) publish a new military specification for PFAS-free foams and that PFAS-free foams be available for military use by the end of 2023.

To date, no commercial PFAS-free foam technologies meet the fire performance or inter-compatibility requirements needed for military use. In part, this is because the DoD evaluates all fire suppressant foams against MIL-PRF-24385F ("Fire Extinguishing Agent, AFFF Liquid Concentrate, for Fresh and Sea water"). MIL-PRF-24385F specifies fire extinguishment and burn back times under certain test conditions, but these parameters were determined from the capabilities of AFFF. No commercial PFAS-free foam alternatives can achieve these fire extinguishment and burn back suppression times. However, failing to meet the current military specification (MILSPEC) is not necessarily an indication of a foam's inability to extinguish fire in operational environments. Alternative test specifications are needed for PFAS-free foam, either by establishing new minimum performance requirements under the current MILSPEC, meeting existing performance criteria through alternative delivery mechanisms (applicator, application rate, etc.), or by developing more relevant screening methodologies altogether.

TDA Research, Inc.'s (TDA) objective is to collect baseline data for the PFAS-free foam under MIL-PRF-24385F to inform what specifications could be adjusted to fully evaluate PFAS-free foams for fire suppression and environmental impact. The project team will evaluate the PFAS-free foam against MIL-PRF-24385F to establish minimum performance requirements under those test parameters and they will explore what, if any, alternative delivery mechanisms could be included in the new MILSPEC so that the PFAS-free foam meets the MIL- PRF-24385F fire extinguishment and burn back times. The project team will investigate the impact of the operational environment (elevated air temperature, fresh versus sea water) on PFAS-free foam performance, and will demonstrate compatibility with military materials. Finally, the project team will perform extended shelf-life studies to demonstrate formulation stability and will conduct extensive health and environmental impact tests.

TDA has developed a novel, environmentally friendly PFAS-free foam containing proprietary components that improve the flow of the foam over burning hydrocarbon fuels and reduce fuel transport through the foam. The foam is low expansion, non-toxic at concentrations of >100 mg/L, low viscosity, and compatible with equipment (nozzles and pumps) used for AFFF delivery.

This project will fill in knowledge gaps about the performance and properties of PFAS-free foam, inform a technical specification for PFAS-free foams that will replace AFFFs in 2024. TDA's proprietary PFAS-free foam formulation is effective, non-toxic, and biodegradable; further characterization of the foam performance will help to establish baseline values for foam performance.