There are a wide range of well-established fire suppression technologies, including water sprinklers, inert gases, carbon dioxide, water mist, dry chemical agents, halons, and HFCs. More recently new agents have been introduced including a fluoroketone, a bromofluoro-olefin, iodotrifluoromethane and potentially a hydrofluoro-olefin – an HFO candidate.
Fluorocarbon based extinguishants are described as ‘clean agents’ that do not leave any oily residues, particulates, or water damage and rapidly extinguish fires with an excellent weight to effectiveness ratio. Many/most are safe to use around people (occupied spaces) and offer unique advantages in speed, performance and safety. Many critical high value applications require some or all of these properties to preserve life, property and the environment while maintaining continuity of operations. Clean agents protect data centres and telecommunication networks, power plants and substation distribution grids, airports, metro lines, museums and medical facilities. Commercial airplanes, military vehicles and ships use clean agents to lives. From MRIs looking inside the human body to telescopes looking to the farthest reaches of the universe, Fluorocarbon clean agents protect a broad range of applications and technologies critical to the world we live in.
HFC-227ea is widely used in installed fire suppression/prevention systems to protect essential facilities such as air traffic control centres, data centres and telecommunication networks around the world. HFC-227ea can be used for occupied spaces (HFC-227ea is also used as a propellant for pharmaceutical Metered Dose Inhalers for asthma and COPD). The HFC-227ea clean agent remains in the system cylinder until required to extinguish a fire. F-Gas Regulation 517/2014 requires regular leak checks to assure the material does not leak to the environment and is available to extinguish when required. If a system is decommissioned the HFC-227ea can be easily removed, recycled and reused for recharging a system or in new
HFC-125 and HFC-236fa are also used as clean agent fire extinguishants due to their fire suppression performance. HFC-125 has been used successfully as an alternative to halon for engine fire protection on US military aircraft developed since the early 1990s. HFC-236fa is primarily used in portable fire extinguishers and large flight line wheeled unit extinguishers.
The F-Gas Regulation banned the use of HFC-23 from 2016, due to its very high global warming potential and the availability of alternative fire suppression systems.
HFO-1336mzz(Z) is being proposed as suitable for some applications. Due to its boiling point, mixtures with an inert gas such as nitrogen or carbon dioxide would be required. It has an ultra-low GWP and is not subject to the F-Gas Regulation phase-down for HFCs.
Halons are very effective as they contain bromine which is active at supressing flame propagation. They were widely used in the 1970s and 80s however, because they contain bromine and have long atmospheric lifetimes, they have high ozone depletion potentials and production of new halon ceased in the early 1990’s under the Montreal Protocol. Halon 1301 continues to be used on all commercial aircraft, supported through recycling of installed fire systems.
The EU banned all non-critical uses of halons in 2003. Critical uses are listed in the current Annex VI to Regulation (EC) No. 1005/2009. All current on-board uses of halons in aviation are included on the critical use list under the EC regulation. Annex VI was revised in 2010 as per Commission Regulation (EU) No 744/2010 of 18 August 2010 which contains “cut-off dates” for the use of halons in new designs of equipment or facilities and “end dates” when all halon systems or extinguishers in a particular application must be decommissioned (i.e. ‘retrofit’)
Some clean agent applications, particularly onboard aircraft, are very challenging and active agents similar to halons are most appropriate. Agents containing bromine, chlorine and iodine typically have lower space and weight requirements which makes them particularly suitable for use on aircraft. Fire extinguishants containing bromine, chlorine or iodine can be much more effective than HFCs, but typically have higher toxicity (lower exposure limits compared to HFCs) and lower stability. A bromofluoro-olefin, HBFO-1233xfB, (CF3CBr=CH2 or 2-bromo-3,3,3-trifluoropropene, shortened as 2-BTP) has been approved for use on aircraft as a streaming agent for use in handheld extinguishers to replace halon 1211. It has favourable environmental characteristics with a GWP of 0.26 and has a very short atmospheric lifetime (7 days).