1. ALTERNATIVES TO HALON FIRE EXTINGUISHANTS Dr David Liddy

2. ALTERNATIVES TO HALON FIRE EXTINGUISHANTS Introduction Halons, their properties, advantages and disadvantages Types of alternative, their properties, advantages and disadvantages Commercialised alternatives Implemented and potential alternatives, for both critical and non-critical installations Gaps in the market - research and development of additional options Selecting and implementing alternatives – issues, practicalities, affordability Sources of further advice and guidance

3. ALTERNATIVES TO HALON FIRE EXTINGUISHANTS Halon properties, advantages and disadvantages The key properties of the halons include: chemical reactivity (in a flame, a cylinder, the environment, a person) and their physical properties (boiling point/volatility); these properties define the halons’ suitability for particular applications – effectiveness, toxicity, stability, practicality and environmental impact Each halon has different properties, but each reacts chemically and catalytically with the flame, making it a very effective extinguishant by weight and volume The catalytic effect is mainly due to the bromine (Br) atoms in the halon molecule – Br reacts to remove a flame’s active species and is continually regenerated in the process; chlorine (Cl) is not so effective; fluorine (F) reacts with the flame species but is consumed in the process; a fluorocarbon without Br is a much less effective extinguishant; iodine (I) also reacts catalytically and so makes for an effective halon extinguishant, but tends to make the halon more toxic Halogen atoms on their own are reactive and toxic; combining them with carbon and F in a halon molecule increases stability and reduces toxicity, so is better for fire extinguishing; it also ensures released halons migrate to the stratosphere where the Br and Cl catalytically react with ozone; it’s an unavoidable trade-off

4. ALTERNATIVES TO HALON FIRE EXTINGUISHANTS Halon properties (continued) Each halon is a gas or volatile liquid that penetrates spaces and the fire and leaves no residue or contamination – a clean agent The higher the halon’s boiling point is, the less easily it floods a space, especially at low ambient temperatures, and the better it is as a streaming agent where a jet of halon can be aimed at the source of a fire some distance away. Volatility determines the suitability for particular applications, and the means of storage. Pressurisation of the cylinders (usually with nitrogen) is necessary to ensure a speedy discharge of the halons. The halons are Non-conductive, so can be used on electrical equipment Clean, with no residues to clean up Not perfect – they do not absorb heat so the re-ignition of a fire is always a possibility when the halon concentration reduces over time or when a protected enclosure is opened

5. ALTERNATIVES TO HALON FIRE EXTINGUISHANTS Types of alternatives, their properties, advantages and disadvantages There is no single ideal alternative to the halons, so a wide range has been developed for the market ‘Traditional’ extinguishants water; carbon dioxide; chemical (dry) powders; foam Developments of traditional extinguishants water mist/fine water spray; very fine chemical powders Inert gases nitrogen; argon; blends of the two Halocarbons (gases and volatile liquids) Hydrofluorocarbons (HFCs); other fluorocarbons Newer technologies Inert gas generators; pyrotechnically generated aerosols

6. ALTERNATIVES TO HALON FIRE EXTINGUISHANTS Traditional extinguishants – water Well understood, economic, widely used in portable extinguishers and fixed (flooding) systems (sprinklers) Extinguishes fires mainly by heat absorption Effective on class A (cellulose-based solids, e.g. wood, paper, textiles) fires but ineffective/dangerous against class B (flammable liquid) fires and on electrical equipment. Not strictly a clean agent; although there will be minimal residue, the large quantities of water often used may damage protected assets Minimal harmful effects on persons unless contaminated Minimal adverse environmental impact

7. ALTERNATIVES TO HALON FIRE EXTINGUISHANTS Traditional extinguishants – carbon dioxide (CO 2 ) Well understood, economic, widely used in portable extinguishers and fixed (flooding) systems Extinguishes fires by a combination of heat absorption and oxygen level reduction Effective on class A (cellulose-based) and class B (flammable liquid) fires and on electrical equipment. Clean agent, but thermal shock (freezing) may damage some more fragile protected assets CO 2 is lethal at the design concentration necessary for a total flooding system protecting an enclosed space; safeguards must be engineered into any such system to ensure personnel are not exposed; there is a small risk of frost damage to skin from incorrect operation of portable extinguishers Minimal adverse environmental impact

8. ALTERNATIVES TO HALON FIRE EXTINGUISHANTS Traditional extinguishants – dry (chemical) powders Well understood, economic, widely used in portable extinguishers; generally not suitable for fixed (flooding) systems because of poor distribution of the powder around an enclosure and rapid settling Available in a variety of forms (different salts), including monoammonium phosphate, sodium and potassium bicarbonates and potassium chloride, each with different properties, performance and suitability for different fire risks; (wet chemical extinguishers are also available; the salts may also be added to water extinguishers to reduce risk of freezing) Extinguish fires mainly by a catalytic chemical interaction with flame species and some variants are the most effective extinguishants by weight and volume May be effective on class A (cellulose-based) and class B (flammable liquid) fires and on electrical equipment, depending on the type Not a clean agent; deposited powders may damage some protected assets (corrosion, clogging) and must be cleaned up Dry powders may cause skin and respiratory irritation, but use by trained personnel in portable extinguishers is not likely to be a significant hazard Minimal (localised) adverse environmental impact

9. ALTERNATIVES TO HALON FIRE EXTINGUISHANTS Traditional extinguishants – foams Well understood, economic, widely used in portable extinguishers and some fixed (flooding) systems in specialised applications (e.g. ships, petrochemicals facilities) Available in a variety of forms and compositions to address different fire risks, most commonly aqueous film-forming foams (AFFF) and high expansion foams; both extinguish fire mainly by oxygen level reduction through blanketing of the fuel surface or exclusion of oxygen from the flames; Effective on class A (cellulose-based) and class B (flammable liquid) fires. AFFFs are not suitable for use on electrical equipment. Not clean agents; foam residues may damage some protected assets Personnel exposure to foams is unlikely to present a significant hazard, but such exposures should be minimised where possible (see below). Certain fluorinated surfactants in some AFFFs are toxic and may accumulate in biological systems and cause significant adverse environmental impact; although less harmful compositions are being introduced, any continual seepage and contamination of groundwater should be avoided; fire training facilities, in particular, must implement safeguards to prevent such contamination.

10. ALTERNATIVES TO HALON FIRE EXTINGUISHANTS Developments in traditional extinguishants – water mist/fine water spray Now well understood, economic, fixed systems increasingly used in commercial shipping (cruise ships) and military vessels; technology being developed for use in portable extinguishers; additives may improve low temperature performance Extinguishes fires mainly by heat absorption, more rapidly and effectively than conventional sprinklers because of the fine water droplets and using much small quantities of water Effective on class A (cellulose-based) and class B (flammable liquid) fires and, possibly, on electrical equipment; may not be 100% effective in cluttered spaces but should control any fire enabling final extinguishment by trained personnel; systems require very careful design to ensure adequate distribution of water droplets of the correct size to address the fire risks present Not strictly a clean agent, but the small amount of water used minimises potential damage Non-harmful, so safe to activate a discharge when personnel are present; the water mist may also protect personnel from the heat and smoke from a fire; safety implications of any additive would need to be considered No adverse environmental impact

11. ALTERNATIVES TO HALON FIRE EXTINGUISHANTS Developments in traditional extinguishants – very fine chemical powders Increasingly understood, economic, with potential use in portable extinguishers and fixed systems to protect small unoccupied spaces Extinguish fires mainly by a catalytic chemical interaction with flame species and variants are very effective extinguishants by weight and volume; compaction of powders may reduce effectiveness unless addressed in manufacture of the powder and maintenance of the extinguishers Most fine powders are effective on class A (cellulose-based) and class B (flammable liquid) fires and on electrical equipment, depending on the chemical composition Not clean agents; deposited powders may damage some protected assets (corrosion, clogging) and must be cleaned up Dry powders may cause skin and respiratory irritation, but use in portable extinguishers or small fixed systems protecting unoccupied spaces is not likely to be a significant hazard Minimal (localised) adverse environmental impact

12. ALTERNATIVES TO HALON FIRE EXTINGUISHANTS Inert Gases – nitrogen, argon, or blends of these Well understood; widely used in fixed systems protecting normally occupied spaces in buildings; large high pressure distribution systems and storage cylinders are needed to contain the quantities of gas needed; the high cost of the storage and distribution systems is balanced somewhat by the low cost of extinguishant; not suitable for enclosures where space is limited, e.g. mobile applications; not suitable for portable extinguishers Extinguish fires mainly by reducing oxygen to levels which do not support combustion (<14% by volume) Effective on class A (cellulose-based) and class B (flammable liquid) fires and on electrical equipment. Clean agents, causing no harm to protected assets Non-harmful in themselves; low oxygen levels may be harmful to vulnerable personnel if they are exposed for extended periods No adverse environmental impact

13. ALTERNATIVES TO HALON FIRE EXTINGUISHANTS Halocarbon gases and volatile liquids – containing carbon, fluorine and hydrogen only Several different types are available on the market, each with different properties and potential applications; most are hydrofluorocarbons (HFCs); one is a fluorinated ketone; at least one other is in development but with no information yet made public Available HFCs include HFC-227ea (e.g. trade name of FM-200), HFC-23 (FE-13), HFC-125 (FE-25), HFC236fa (FE-36) The fluorinated ketone is CF 3 CF 2 (O)CF(CF 3 ) 2 or FK-5-1-2, known by the trade name Novec 1230 HFCs are well understood and commonly employed in fixed systems protecting normally-occupied spaces in buildings and some mobile equipment such as military vehicles and ships; halon-like storage and distribution systems (except for HFC-23) balance relatively high cost of the chemicals; HFC-125 has low BPt so is suited to low temperature applications; HFC-236fa has a higher BPt and is better suited for portable extinguishers FK-5-1-2 is newer to the market but increasingly implemented in fixed systems to protect occupied and unoccupied spaces; remains under development for portable applications but its higher Bpt would seem to make it potentially suitable for these applications; performance at low ambient temperatures would need to be verified

14. ALTERNATIVES TO HALON FIRE EXTINGUISHANTS Halocarbon gases and volatile liquids (continued) Extinguish fires mainly by chemical interaction with flame; it is not catalytic mechanism, so 2-3 times weight and volume of halon may be needed for comparable extinguishing performance Effective on class A (cellulose-based) and class B (flammable liquid) fires and on electrical equipment; careful design of extinguishing systems is needed to optimise the performance of the halocarbons Clean agents, causing no harm to protected assets; however, breakdown products may cause minor corrosion of materials in certain circumstances (see below) Most HFCs are not harmful at extinguishing concentrations; for some, the margin between safe and extinguishing levels is narrow; however, harmful levels of breakdown products (acidic gases) may result from discharge of a halocarbon onto a large fire, so personnel should leave a protected space before discharge and not re-enter until the safety of the enclosure atmosphere is verified Different HFCs have different, but significant, global warming potentials (especially FE-23, which has one of the highest known GWPs); release to atmosphere will contribute to climate change; use and management are regulated by EU Regulation to minimise those emissions but use in fire protection is permitted; FK-5-1-12 has a very short atmospheric life and low GWP, so a minimal adverse environmental impact

15. ALTERNATIVES TO HALON FIRE EXTINGUISHANTS Newer technologies – inert gas generators (IGGs), pyrotechnically- generated aerosols (PGAs) Potentially economic and effective solutions for niche applications – canisters fixed inside small unoccupied spaces rapidly release inert gases (IGGs) or very fine particulate salts (PGAs); no distribution pipework is needed IGGs extinguish fire mainly by oxygen depletion through rapid generation of nitrogen, carbon dioxide and water vapour; PGAs extinguish fire by chemical catalytic interaction with flame species; both work by ignition of source chemicals, which releases heat that is retained in the canister; both types are potentially very effective extinguishants by weight and volume Effective on class A (cellulose-based) and class B(flammable liquid) fires and on electrical equipment. PGAs are not strictly clean agents; fine coatings of deposited powders may damage some protected assets (corrosion, clogging) and should be cleaned up Not intended for protection of spaces occupied by personnel due to potential hazards from heat and force of discharged particles and gases, which may cause skin and respiratory irritation Minimal (localised) adverse environmental impact

16. ALTERNATIVES TO HALON FIRE EXTINGUISHANTS Implemented and potential alternatives for both critical and non-critical applications Note: other alternatives may be suitable, and these examples may not be suitable in all cases for the application concerned; each installation must be considered on a case-by-case basis Military vehicles Engines – HFC 227ea, HFC-125, dry (chemical) powders, IGGs, inert gases (1 example only) crew compartments, portables – CO2, dry chemical, HFC-236fa; Crew compartments, explosion suppression systems – no retrofits so far, but potentially water mist/HFC-227ea combined, HFC-227ea Military vessels Machinery spaces – foams, CO2, water mist, HFC 227ea, water/HFC-227ea combined Engine and other compartments – CO2, HFCs Hangar spaces, portables – foams, dry powders, HFC-236fa

17. ALTERNATIVES TO HALON FIRE EXTINGUISHANTS Implemented and potential alternatives (continued) Aircraft Engine nacelles – HFC-125 and CF 3 I meet regulators’ minimum performance standards (MPS); HFC-125, IGGs implemented in several military new designs; no alternatives yet implemented in civil aircraft; FK-5-1-12 being evaluated against approved MPS Cabin portables, military – CO 2, dry chemical, HFC-236fa implemented in some aircraft Cabin portables, civilian – HFC-227ea and HFC -236fa meet approved MPS but have not yet implemented in any aircraft (weight penalty cited) Cargo compartments – IGG, on-board IGG (military, some new designs only); no alternatives yet meet an approved MPS for civil aircraft; industry working group (ICCAIA) recently established to drive progress Lavatory waste bins – HFC-236fa, HFC-227ea meet approved MPS and implemented in most new aircraft and some existing aircraft, both military and civil Military dry bays – IGGs, PGAs, on-board IGG; new designs only Military fuel tank inerting – on-board IGG, fire suppression foam (new designs only)

18. ALTERNATIVES TO HALON FIRE EXTINGUISHANTS Implemented and potential alternatives (continued) Other aviation applications Airfield Crash Rescue Vehicles – foams, dry (chemical) powders Airfield portable (trolley) extinguishers – foams, (chemical) powders, HFC-236fa Oil, gas and petrochemical facilities Fixed systems – foams, water mist, CO 2, inert gases, HFC-227ea, HFC-23 Portable extinguishers – foams, CO 2, dry (chemical) powders Cargo ships Machinery and other spaces – foams, CO 2, water mist, HFC 227ea Command and communications facilities, computer rooms, heritage buildings, museums Fixed systems – inert gases, CO 2, HFC-227ea, FK-5-1-12 Portables – water, foams, CO 2, dry (chemical) powders, HFC-236fa, FK-5-1-12 Other Fire brigades, portables – foams, dry (chemical) powders, CO 2 Protection of personnel, portables – foams, dry (chemical) powders, HFC-236fa, FK-5-1-12 Boats and vehicles, portables – water, foams, CO 2, dry (chemical) powders, FK-5-1-12

19. ALTERNATIVES TO HALON FIRE EXTINGUISHANTS Gaps in the market - research and development of additional options All commercialised alternatives have significant disadvantages, so none is suitable for all the applications for which halons were adopted Considerable effort has been expended to develop and market the current range of options; the focus of effort remains on developing and refining the application of these to remaining problem areas, including merging the technologies (e.g. water mist with halocarbons, water with additives, fine powders with halocarbons or gels) Some research and development continues by governments and industry into additional options, but pace is slow because of the small remaining niche markets (mainly military and aviation applications) A notable example is bromo-trifluoropropene (BTP), a brominated halocarbon that performs like halon but has very low ODP because of short atmospheric life; many of its properties are comparable to halon 1211; not yet commercially available but undergoing toxicity testing and well-progressed in development Another halocarbon of possible interest, though not especially new: CF 3 I is the only halon-like alternative currently on the market; uptake has been minimal because of concerns about potential toxicity; otherwise, it is a very effective extinguishant, comparable to halons by weight and volume, with minimal adverse environmental impact; available in research quantities

20. ALTERNATIVES TO HALON FIRE EXTINGUISHANTS Selecting and implementing alternatives – issues, practicalities, affordability Selection of an alternative should be considered by competent fire protection engineers and include an evaluation of the full range of risks and solutions Halon systems may have been ‘over-engineered’ or installed where not really necessary, so alternative options should not be dismissed without a full re- assessment of the fire risks involved and alternative means to reduce those risks (e.g. passive fire protection) With the possible exception of aircraft engine and cargo compartments one or more of the available alternatives will be technically and economically feasible for new designs of facility and equipment, where adjustments can be made to optimise the alternative extinguishants’ performance Retrofit of existing equipment and facilities will be more problematic and expensive, with opportunities for any necessary modifications more limited, probably to periods of major maintenance or upgrade New developments may lead to more economical alternatives in the longer term (5 years plus) but should not delay consideration of current alternatives when retrofit opportunities arise

21. ALTERNATIVES TO HALON FIRE EXTINGUISHANTS Selecting and implementing alternatives (continued) Implementation of any alternative will require more careful design of the total fire protection system to optimise its performance and safety Factors to consider which will quickly help narrow down the options include: Type and causes of potential fires, including fuel loading Space and weight restrictions (agent distribution and storage) Enclosure integrity (strength, openings, ventilation) Enclosure volume and ‘clutter’ (net volume) Ambient operating temperatures and pressures, including extremes Detection options (rapid but assured) Availability of trained firefighters Presence of personnel and whether they must remain in the protected space (military vehicles and ships, aircraft) Environmental implications Installation and through-life costs

22. ALTERNATIVES TO HALON FIRE EXTINGUISHANTS Sources of further advice and guidance UNEP Halons Technical Options Committee (HTOC) – assessment reports every 4 years; technical notes on a range of subjects, including halon alternatives, updated as required. Available from: http://ozone.unep.org/teap/Reports/HTOC/ DEFNET – EU Member State MODs’ Defence Environmental Network, informal network of environmental experts that meets in a plenary each year and is a forum for working together to resolve environmental problems. To join: http://www.eudefnet.com/ and follow the ‘Contact’ link, or email: secretariat@eudefnet.com http://www.eudefnet.com/ secretariat@eudefnet.com The ODS policy and procedures published by UK MOD (other examples will exist) provides more information on available alternatives and factors to consider in implementing them: https://www.gov.uk/government/publications/jsp-418-mod- corporate-environmental-protection-manualhttps://www.gov.uk/government/publications/jsp-418-mod- corporate-environmental-protection-manual Background note for Member States on the (draft) new Annex VI to Regulation (EC) No 1005/12009, prepared by the European Commission (2009)