The phase-out of ozone depleting chemicals (ODC) such as Halon 1211 has threatened the ability of the military, and civilian aircraft companies, to provide a powerful, clean means of suppressing fires. Additionally, the U.S.Environmental Protection Agency (EPA) has indicated that the replacement fire- fighting agents originally developed as substitutes for Halon 1211 all have greenhouse warming potential or ozone depletion potential (ODP).
This project focused on advanced fire suppression agents which sought to identify, evaluate, and validate environmentally and occupationally safe streaming agents for drop-in replacement of Halon 1211 in wheeled 150 lb flight-line fire extinguishers and in portable aircraft and facility extinguishers.
Several new tropodegradable halocarbon compounds for replacing Halon 1211 have been identified by developing and employing a Quantitative Structural Property Relationship (QSPR) computer model to predict the compounds that have the powerful fire suppression benefits of Halon 1211 without its high ODP. Candidate replacements have been synthesized and screened for a variety of attributes including effectiveness, compatibility, stability, toxicity, and environmental behavior to ensure suitablity as a streaming agent.
The QSPR model was successful in identifying blends of octafluoro-2-butene and 1-bromopropane as efficient replacements with low ODP, low tropospheric lifetime, and good toxicity properties. Streaming tests of the blends show similar performance to Halon 1211. The QSPR model also was successful in identifying a family of compounds known as brominated unsaturated ethers that are predicted to have excellent fire suppression ability, very low ODP, moderate-to-low toxicity, and several other physical characteristics such as high boiling point and high molecular weight that make them particularly promising.
The technical approach for synthesis and screening of the brominated unsaturated ethers was demonstrated in two phases, Phase 1 Synthesis and Phase 2 Testing. In Phase 1 synthesis, routes for each of the compounds were determined and the results were used to select the brominated unsaturated ethers which could be feasibly produced in terms of cost and quantity. In Phase 2 testing, those compounds that were readily able to be synthesized were subjected to a variety of effectiveness, compatibility, stability, toxicity, and environmental tests to ensure that they are suitable as Halon 1211 replacements.
The phase out of ozone depleting chemicals has threatened the ability of the military to provide a powerful, clean means of suppressing fires previously afforded by Halon 1211. The replacements originally developed as substitutes for Halon 1211 have all been caveated for greenhouse warming potential or ozone depletion by the EPA. The Advanced Streaming Agent will be developed fromchemical families which have none of these negative global environmental impacts. This is a technology that has dual use potential and will serve the needs of multiple sectors of the civilian fire fighting community as well as the three military services and the U.S. Coast Guard.