The objective of this Statement of Need (SON) was to develop an automatic fire extinguishing system that uses low global warming potential (GWP) materials for fire suppression in occupied spaces. Proposals should have reflected realistic operating conditions to demonstrate fire suppression in crew compartments against petroleum, oil and lubricant (POL) explosions. Proposed alternatives had to meet the following requirements:

• Fire Suppression: Extinguish all flames without reflash
• Temperature range: -60 to 180°F storage and -25 to 125°F operational
• Agent Concentration: Minimum design concentration must be less than the agent’s lowest observable adverse effects level (LOAEL)
• Combustion: Combustion of the agents must not produce dangerous levels of toxic gases including acid and carbonyl gases including hydrogen fluoride, hydrogen bromide, carbonyl fluoride and other gases (e.g., CO2, CO, NOX, HCN). Levels should not exceed 746 ppm-min per Army requirements.
• Skin Burns: 10-sec dose ≤ 1316°C-sec (2400°F-sec) and heat flux ≤ 3.9 cal/cm²
• Overpressure: Blast pressure must be less than 0.28 bar (4 psi) to prevent ear damage
• Oxygen: Levels must be greater than or equal to 16%
• Ozone Depletion Potential (ODP): Zero ODP, 100-year GWP less than 53, and not be restricted by the American Manufacturing and Innovation (AIM) Act of 2020

Proposals that focused on evaluation of HFC-236fa, HFC-125, 2-BTP, CF3I, HB-55, HCFCs, HFO-1233zd(E), HFO-1336mzz-Z, HFO-1336mzz-E, inert gases, and aqueous agents were not considered. Proposals should have also included a plan to conduct an appropriately-scaled Sustainability Analysis. ¹

¹ https://www.denix.osd.mil/esohacq/home/dod-guidance/dod-sustainability-analysis-guidance/OSD-AS%20SA%20Guidance%20v7%20-%20final%20June%202020.pdf

Program Managers, installations, and Warfighters across all services would benefit from alternative, lower GWP fire and explosion suppressants by enabling uninterrupted supply from a domestic (or friendly) source. Additional reductions in GWP will also enable the Department of Defense (DoD) to meet requirements in domestic regulation and international climate change agreements.

On December 27, 2020, the American Innovation and Manufacturing (AIM) Act of 2020 was enacted in the 2021 Consolidated Appropriations Act. The AIM Act directs the Environmental Protection Agency (EPA) to address hydrofluorocarbons (HFCs) by phasing down the production and import of listed HFCs, managing these HFCs and their substitutes, and facilitating the transition to next-generation technologies. HFC production will be phased down to 15% of current levels by 2036. This follows the same phase down schedule being implemented globally under the Montreal Protocol’s Kigali Amendment, which was ratified in the U.S. Senate in September 2022. Per the AIM Act and EPA regulation, DoD receives HFC allowances to meet mission-critical military end uses (MCMEU). DoD, through inter-Service coordination, is working with the EPA to secure and report the DoD MCMEU allowances. However, there is no guarantee that domestic chemical companies will continue to produce HFCs as overall HFC production limits are phased in.

The AIM Act lists specific HFCs that are commonly used in fire suppression for phase-down, including HFC-227ea, HFC-125, HFC-236fa and HFC-23. HFC-227ea (1,1,1,2,3,3,3-heptafluoropropane) is a widely used fire suppressant in military fire suppression systems on ships and expeditionary/amphibious/combat vehicles. There is a single U.S. domestic production facility for HFC-227ea, with additional suppliers in non-allied countries. HFC-227ea has uses in the medical industry that are allowed under the current structure of the AIM Act; however, industry is actively seeking lower GWP alternatives and anticipates phase down of production and import as soon as alternatives are identified. DoD has evaluated multiple alternative agents in fuel-spray live-fire tests designed to simulate fireball development and blast overpressure that follows a ballistic penetration of the vehicle armor and fuel tank. Test criteria were derived to allow vehicle occupants to remain in the compartment for at least five minutes during and following a fire suppression event without being subjected to immediate or delayed incapacitation. There is no approved alternative for the HFC-227ea used in fire suppression for military uses Overall, it has been found that gaseous low GWP alternatives are more reactive, resulting in shorter atmospheric lifetimes and therefore lower GWPs, also generate much higher levels of toxic gases compared to the more stable, higher GWP chemicals.

The cost and time to meet the requirements of this SON were at the discretion of the proposer. Proposers submitting a Standard Proposal had to provide the rationale for this scale. The two options were as follows:

Standard Proposals: These proposals describe a complete research effort. The proposer should incorporate the appropriate time, schedule, and cost requirements to accomplish the scope of work proposed. SERDP projects normally run from two to five years in length and vary considerably in cost consistent with the scope of the effort. It is expected that most proposals will fall into this category.

Limited Scope Proposals: Proposers with innovative approaches to the SON that entail high technical risk or have minimal supporting data may submit a Limited Scope Proposal for funding up to $250,000 and approximately one year in duration. Such proposals may be eligible for follow-on funding if they result in a successful initial project. The objective of these proposals should be to acquire the data necessary to demonstrate proof-of-concept or reduction of risk that will lead to development of a future Standard Proposal. Proposers should submit Limited Scope Proposals in accordance with the SERDP Core Solicitation instructions and deadlines.