Phase out of Halons

Under the Montreal Protocol Halon 1301, Halon 1211 and Halon 2402 is illegal in developed countries with the following exceptions.

Use of Halon 1301 is permitted:

• in aircraft for the protection of crew compartments, engine nacelles, cargo bays and bays, and fuel tank inerting,
• in military land vehicles and naval vessels for the protection of spaces occupied by personnel and engine compartments, for the making inert of occupied spaces where flammable liquid and/or gas release could occur in the military and oil, gas and petrochemical sector, and in existing cargo ships,
• for the making inert of existing manned communication and command centres of the armed forces or others, essential for national security,
• for the making inert of spaces where there may be a risk of dispersion of radioactive matter,
• in the Channel Tunnel and associated installations and rolling stock.

Use of Halon 1211 is permitted:

• in military land vehicles and naval vessels for the protection of spaces occupied by personnel and engine compartments,
• in hand-held fire extinguishers and fixed extinguisher equipment for engines for use on board aircraft, in aircraft for the protection of crew compartments, engine nacelles, cargo bays and dry bays,
• in fire extinguishers essential to personal safety used for initial extinguishing by fire brigades,
• in military and police fire extinguishers for use on persons.

Note: The list will be reviewed annually, with the intention of removing applications from the list as suitable replacements become available. The list of Critical Uses of Halon, taken from Annex VI of the new EC Regulation 2037/2009 on ozone depleting substances. For more information go to Guidance on EC Regulation No 2037/2000

Evaluation of Alternatives to Halon Fixed Systems

For the purpose of this information, a halon alternative is defined as any permitted form of fire protection that can be used to protect a hazardous area previously protected by halon. Possible alternatives to halons include some long established technologies and new agents that have emerged since the environmental problems associated with halons have been recognised.

Halons have been used to protect a wide range of risks and the choice of alternative has to be based on consideration of the hazard to be protected. The following sections suggest a number of alternative technologies and give an indication of their applicability and limitations. Reference to the publications of the United Nations Environment. Programme Halons Technical Options Committee will also provide guidance to the selection of halon alternatives.

Traditional Alternatives to Halons

• Detection and manual intervention
• Water Sprinkler Systems, including those with pre-action and/or quick response features
• Carbon Dioxide – local application and total flood
• Foam – low expansion, high expansion and foam spray systems
• Dry Powder

New Alternatives to Halons

• Inert Gases
• Halocarbon Gases
• Fine Water Spray/Water Mist
• Inert Gas Generators
• Fine Solid Particulates

Traditional Alternatives to Halons

Detection and Manual Intervention

Especially with the introduction of high sensitivity smoke detection and aspirating systems, it is possible to base a fire protection strategy on suitable detection coupled with arrangements for the fire to be tackled manually with fire extinguishers and hose reels or by the Fire Brigade.

It must be emphasized that detection systems themselves do nothing to suppress the fire (although they may isolate and shut down electrical power sources). Adopting a detection and manual intervention approach represents a major change to your fire protection strategy if you have previously been using a fire suppression system. However, many users have adopted this approach.

Water Sprinkler Systems

Water sprinkler systems are a very common type of fixed fire protection system in the UK and are a long established technology with acknowledged reliability. However, they should not be used for certain hazards including live electrical equipment, fires of flammable liquids, areas of hot working such as salt-baths or anything that would react violently with water.

For shielded fires, such as those in computer cabinets or in switchgear housing, water cannot penetrate in the same way as halon gas, and sprinklers should not be used as the primary system in such fire risks, unless systems are designed with nozzles inside the cabinets. However a sprinkler system will provide safe and effective protection to limit structural damage. Although equipment in the room will inevitably suffer some water damage, the fire itself will cause damage regardless of the suppression system chosen.

One of the most important benefits of sprinkler systems is their outstanding reliability. The records of a major US insurer shows that the probability of a sprinkler accidentally discharging due to manufacturing defects is only 1 in 16 million per year in service. Nonetheless, as an even greater assurance against false discharges, sprinkler systems can be designed so that they only activate if the sprinkler head operates and a separate system of smoke detection is activated. This is called a Pre-Action Sprinkler System. On receipt of signals from two or more detectors, the main control panel automatically opens the control valves, allowing water to flow into the sprinkler pipework in readiness for the first sprinkler to operate. If the sprinkler is damaged without a fire being detected, the system will not release any water, so these systems have particular application where it is essential to ensure that there are no unwanted releases of water.

Another type of system is a dry pipe system. These are designed so that exposed pipework and sprinkler heads do not contain water until the sprinkler is activated; this has particular applications in locations where freezing might occur.

Sprinklers can also be used in conjunction with a gas system, with the sprinklers protecting the main room, and the gas system protecting the floor void.

Areas where sprinkler systems have provided an alternative to halons include computer rooms, control rooms, record storage and cultural heritage.

Carbon Dioxide (CO2) Systems

Carbon dioxide flooding systems have been in use for many years. However, carbon dioxide is an asphyxiant at the concentrations necessary to extinguish fire. Because of this, carbon dioxide total flooding systems should not be on automatic control when the spaces they protect are occupied.

Carbon dioxide is a clean agent with good penetration and is most suited to applications where this is a prime requirement. It is safe to use on live electrical equipment. Carbon dioxide can be used on specific items of enclosed equipment as a localised system. It can also be used to protect enclosed sections of a room, such as the floor void.

Carbon dioxide is stored at high pressure and high concentrations, which is required for it to be an effective extinguishing agent. As a result such systems involve bulky and heavy hardware and are not suitable for applications where space and weight are important considerations.

It should be stressed that if carbon dioxide total flooding systems are used they should be locked off when people are in the protected area. Also, carbon dioxide is odourless and, in addition to locking devices, the use of odourisers on a system may assist in detecting if the system has operated or malfunctioned.

Areas where carbon dioxide systems, locked off or in unoccupied areas, could provide a feasible alternative to halons include telecommunications facilities, computer rooms, control rooms, transformer and switchgear rooms, record storage, cultural heritage, flammable liquid hazards and shipboard machinery spaces.

Foam Systems

The use of low and medium expansion foams is most suited to liquid pool fires, where it acts by forming a barrier between the fire and the supply of oxygen and also by cooling. Foams are not generally effective against running or spray fires. Some liquid fuels, such as alcohols, can destroy some foam blankets by chemical reaction and care must be taken to ensure that an appropriate foam compound is chosen. Since foams are aqueous solutions, they should not be used to protect against anything that would react violently with water.

Developments in systems where foam solutions are delivered through traditional water sprinkler hardware have given rise to increased extinguishing efficiency.

High expansion foam systems can be used as flooding agents in enclosed areas where the foam works primarily by smothering the fire and less by cooling. This makes it suitable for warehousing and document stores or libraries. However, care should be taken in occupied spaces where there is a risk of very poor visibility.

Areas where foam systems could provide a feasible alternative to halons include flammable liquid hazards, engine compartments, computer floor voids, cable tunnels and shipboard machinery spaces.

Dry Powder Systems

Dry powder systems are effective against fires of flammable liquids, including spray fires. Powders are capable of providing very rapid extinguishing but provide little cooling effect and are ineffective once the powder has settled, so the specification of any system must address this. Different types of powders are available to address different types of fire and it is essential to ensure that the powder selected is suitable for use on the risk to be protected.

The levels of chemical toxicity of many powders are low but some require special precautions. All types of powder are unpleasant to breathe, obscure visibility, and would not be recommended for use in occupied spaces. Powders settle out after use and present the problem of post-fire clean up. It can also damage sensitive electrical equipment.

Areas where dry powder systems could provide a feasible alternative to halons include flammable liquid hazards, shipboard machinery spaces and vehicle engine spaces.

New Alternatives to Halons

There is a strong demand for clean agents that are electrically non-conductive, leave no residue, are relatively non-toxic and have good penetration. Of the alternatives listed below, the following can meet some or all of those requirements:

• Inert Gases
• Halocarbon Gases
• Inert Gas Generators

Inert Gases

Inert gas agents are electrically non-conductive clean fire suppressants that are used in design concentrations of 35-50% by volume to reduce ambient oxygen concentration to between 14 and 10%. Oxygen concentrations below 14% will not support the combustion of most fuels (and human exposure must be limited).

Several gases and mixtures are available commercially.

When choosing an inert gas agent the following should be considered :

• They are not liquefied gases. They are stored at high pressure in gas cylinders, which has implications for space and weight.
• Inert gases will require a system that is sufficiently robust to withstand the pressures involved; the hardware required for this will be similar to that for CO2 systems.
• The component gases of mixtures are blended so as to have a density similar to that of air. This means that they retain their concentration in the risk area better than halon.
• Discharge times are of the order of one or two minutes. This may limit some applications involving very rapidly developing fires.
• Inert gases are not subject to thermal decomposition and hence form no breakdown products.
• Inert gases are asphyxiant’s and the health and safety aspects must be considered.
• There is no concern regarding ozone depletion or global warming from inert gases.

Areas where inert gas systems could provide a feasible alternative to halons include telecommunications facilities, computer rooms, control rooms, transformer and switchgear rooms, record storage, cultural heritage, flammable liquid hazards and shipboard machinery spaces.

Halocarbon Gas Systems

The halocarbon’s (CFCs) and (HCFCs) were phased-out under the Montreal Protocol and a number of fire extinguishing halocarbon gases with zero ozone depletion potential (ODP) have been developed. The substitute gases used for firefighting purposes tend to be fluorinated gases belonging to a class of chemicals known as hydrofluorocarbons (HFCs) and perfluorocarbons (PFCs).

Fluorinated gases do not damage the ozone layer like (CFCs) and (HCFCs), however they are powerful greenhouse gases, are generally long-lived and are included in the basket of gases under the Kyoto Protocol. The Kyoto Protocol placed legally binding requirements on signatories to reduce their carbon (and equivalent) emissions to below 1990 levels. Reducing fluorinated gas emissions will contribute towards meeting this obligation.

Europe has a policy to strictly control the use of these fluorinated gasses and this makes things very difficult for organisations using these gases. They are revising legislation to take account of this problems and this will make things even more problematic in the future. The latest restriction are PFC’s are now illegal and HFC’s are legal, but subject to leakage check requirements,

• All system cylinders must have pressure gauges or indicators
• Systems over 300kg must have a leakage warning alarm
• Users should carry out and record regular checks for leakage
  • Weekly in accordance with the normal maintenance requirements
• In addition, detailed leak detection checks by a certified person (likely to be the system servicing company)must be carried out as follows,
  • At least every 12 months for systems having more than 3 kg gas
  • At least every 6 months for systems having more than 30 kg gas
  • At least every 3 months for systems having more than 300 kg gas
• Leakage inspection within 1 month after a leak has been repaired

The list is not exhaustive and none of the agents can be considered as a drop-in replacement for halon 1301, in the same system. Redesign and modification, if not replacement, will be required. However, the new halocarbon agents share many of the characteristics of halons:

• They are electrically non-conductive
• They are clean agents in that they vaporise readily and leave no residue
• They are stored as liquefied compressed gases and use hardware similar to that used for halon 1301
• They are space and weight efficient.

When choosing a new halocarbon agent the following should be considered:

• Environmental Aspects; while the HFCs and PFCs do not affect the ozone layer, they are greenhouse gases that fall under the Kyoto Protocol and so any release, though probably rare, would count towards the national emissions inventory of global warming gases. Therefore these gases should only be used where other safe, technically feasible cost effective and more environmentally acceptable alternatives do not exist.
• FE-13, unlike the others listed, has a high vapour pressure and will require a system that is sufficiently robust to withstand it; the hardware required will be similar to that of CO2 systems.
• Halon 1301 produces HBr and HF breakdown products in a fire. The new agents produce HF in greater quantities but no HBr. However, an uncontrolled fire can in itself produce large amounts of toxic and corrosive combustion products in addition to smoke and heat.

Areas where halocarbon gaseous agent systems could provide a feasible alternative to halons include telecommunications facilities, computer rooms, control rooms, transformer and switchgear rooms, record storage, cultural heritage, flammable liquid hazards, shipboard machinery spaces and aero engine compartments.

Fine Water Spray/Water Mist

Fine water spray systems fall into two main categories: single fluid systems, utilise water stored at 40-200 bar pressure and spray nozzles that deliver droplet sizes in the range of 10 to 100 microns  diameter; dual systems use air, nitrogen or another gas to atomise water at the nozzle. In both cases, the resulting heavy mist behaves in some respects like a dense gas but will not diffuse into shielded areas, consequently each water mist system has to be designed individually and a requirement may remain for response team intervention to extinguish small, obstructed fires.

The quantity of water required can be up to 100 times less than that in a sprinkler system. The result of this is that water mists do not conduct electricity in the same way as a solid stream of water, so sprays can be considered for use on live electrical equipment. Fine sprays can also be used on fires of flammable liquids but should not be used on substances that will react violently with water, such as reactive metals.

The major difficulties with water mist systems are those associated with design and engineering. The requirements to generate, distribute and maintain an adequate concentration of correctly sized droplets throughout the space mean that fire protection solutions must be individually tailored. Nevertheless, the technique is gaining approval.

Areas where fine water spray/water mist systems could provide a feasible alternative to halons include transformer and switchgear rooms, record storage, cultural heritage, flammable liquid hazards, shipboard accommodation, storage and machinery spaces and combustion turbine enclosures.

Inert Gas Generators

Inert gas generators utilise a solid material which oxidises rapidly, producing large quantities of CO2 and/or nitrogen. This technology is a recent and continuing development, and its use has so far been limited to specialised applications such as engine nacelles and dry bays on a few new military aircraft where space and weight are major considerations. Significant work would be required to expand application of this technology to occupied areas but there is no concern regarding ozone depletion or global warming from inert gas generators.

Areas where inert gas generators might provide a feasible alternative to halons include aero engine compartments and aircraft dry bays.

Fine Solid Particulate Technology

This relatively new technology is used in conjunction with inert or halocarbon gases and so is included here. Aerosol and inert gases are formed pyrotechnically and may also require a halocarbon carrier gas; the solid aerosol acts directly on the flame, cooling it, the gases serve as a mechanism for delivering the aerosol to the fire. Solid particulates have very high effectiveness to weight ratios. They also have the advantage of reduced wall and surface losses relative to water mist and the particle size is easier to control. However, they may damage sensitive equipment, are not suitable for explosion suppression due to the high temperature at which they are generated and there are severe physiological problems associated with inhalation of particulate material in the size range required. These problems limit the utility of this technology to unmanned areas.

Areas where fine solid particulate systems could provide a feasible alternative to halons include telecommunications cabinets and automotive, boat and aero engine compartments.

Summary of Alternatives and their Applications

The table summarises the alternatives to halon, which might be considered for a range of risks and in a range of applications. It must be emphasised that not all the recommended alternatives will be equally applicable in all such cases. Also, no account has been taken of issues such as the cost of the systems, the cost and complexity of installation, especially in differing circumstances such as new build versus retrofit, or of the level of maturity of and experience with the technology. All hazards are different, and it will continue to be important to obtain the advice of appropriate technical experts before selecting an approach.

Key :

• yes – means the alternative can be considered for the hazard
• no – means the alternative is not suitable for the hazard

Selecting a System

Once you have established which systems are technically capable of protecting against the hazard, the individual requirements for a specific project then need to be evaluated.

You may find the following checklist useful when selecting an alternative :

Fire Fighting Effectiveness

• Speed of fire suppression
• Suitability for the fire hazard
• Post-fire hold time
• Ability to permeate
• Risk of re-ignition

Discharge Damage/Effect on Equipment (Collateral Damage)

• Clean up
• Water damage
• Decomposition products and corrosion
• Condensation
• Thermal shock

Installation Issues

• Floor space/weight
• Pipework
• Ease of maintenance
• Time to re-instate system
• Installed cost
• Refill cost
• Availability of extinguishing agents

Suitability of Room for Gaseous System

• Capability of room to hold gas
• Desirability of room integrity test
• Need to seal leak paths

Hazards for Occupants

• Toxicity
• Noise levels
• Pressurisation
• Visibility
• Inhalation
• Safety with live electrical equipment
• Thermal decomposition products

Environmental Acceptability

• Ozone depletion
• Global warming
• Atmospheric lifetime

Maintenance

There is a statutory requirement for the regular maintenance, inspection and testing of fixed fire protection systems. This should be carried out by a competent person in accordance with the relevant British Standard or the manufacturer/installer specifications. Systems should also be serviced annually by a competent person.

Environmental Issues

When considering an alternative to halon, you should look at its possible environmental impact.

HCFCs

Hydrochlorofluorocarbons (HCFCs) have ozone depletion potentials, and although they are less than those of halons, HCFCs remain controlled substances under the Montreal Protocol. EC Regulation 3093/94 (the previous Regulation on the use of ozone depleting substances in the EU) has already prohibited their use in fire fighting.

Global Warming and the Kyoto Protocol

Hydrofluorocarbons (HFCs) and Perfluorocarbons (PFCs) are important alternatives and replacements for some uses of ozone depleting substances. They are not ozone depleting gases and therefore are not covered by the Montreal Protocol but they are greenhouse gases (along with carbondioxide, methane, nitrous oxide and sulphur hexafluoride). The UK’s legally binding target under the Kyoto Protocol is to reduce emissions of all
these greenhouse gases, together, by 12.5% based on 1990 or 1995 levels in the years 2008-2012.

UK Voluntary Agreement

UK Government and the UK Fire industry are reviewing the Voluntary Agreement on further reducing emissions of HFCs and PFCs in fire fighting applications in line with the UK Climate Change Programme.

Global Warming Potentials and Atmospheric Lifetimes

Leakages

The new EC Regulation requires that all precautionary measures practicable shall be taken to prevent and minimise leakages of halons and other ozone depleting substances from fire protection systems during their manufacture, installation, operation and servicing.

You should take similar steps for systems containing HFCs, PFCs and other greenhouse gases. Clearly, this is desirable anyway: a leak in any fire protection system will affect the extinguishing performance and may even result in failure of the system.

Waste Regulations

Waste halons are already controlled by the waste management controls in the Waste Management Licensing Regulations 1994 and the Environmental Protection Act 1990. The relevant provisions are sections 33(1)(c) and 34 of the 1990 Act, which are designed to ensure that waste travels only along legitimate routes towards proper disposal or recycling without harm to the environment or health.

Section 33 prohibits the disposal and recovery of waste in a manner likely to cause pollution of the environment or human health. The duty of care imposed under section 34 requires all producers and holders of waste (except householders) to take all reasonable steps to keep the waste safe and ensure it is treated lawfully. Anyone concerned with controlled waste must ensure it is managed properly, recovered or disposed of safely; and must only transfer it, with a description of the waste, to someone who is authorised to receive it. Those authorised to receive controlled waste are registered waste carriers or brokers, local authority waste collectors and waste operations with a waste management licence or registered exemption from licensing.

Taken together, these provisions oblige the producer and holders of waste ODS to prevent, as far as reasonable in the circumstances, their release to the atmosphere through their own actions or those of others. You should therefore take great care to avoid any discharge of such controlled wastes and to ensure that all who handle them are authorised for the purposes of the duty of care.

Transboundary shipments of waste halons to other EU Countries are only permitted for recovery. Each movement is subject to the prior informed consent regime set out in the EC Waste Shipments Regulation EC 259/93.

System Testing

Pressure testing techniques are available which enable the gas tightness of a room to be accurately valuated and for leak paths to be identified and sealed, thus increasing the time that the gas will be retained in the room and satisfying the requirements of the BFPSA Code of Practice for Gaseous Fire Fighting Systems. These techniques do not involve the discharge of any gas. Your supplier will be able to give you further information on how to test and maintain systems properly and safely

Health and Safety Issues

Fire precautions systems are covered both by fire precautions legislation and by health and safety at work legislation :

• In some, albeit few, cases there are specific regulations relating to the selection and use of fire extinguishing systems. For example, the Fire Precautions (Sub-surface Railways) Regulations 1987 contain specific requirements for sprinkler systems.
• The risks from using the fire extinguishing system, and from the fire itself, need to be assessed under :
  • The Regulatory Reform (Fire Safety) Order 2005
  • The Management of Health and Safety at Work Regulations 1999 (MHSWR) and ;
  • If the system contains carbon dioxide; the Control of Substances Hazardous to Health Regulations 2002 (COSHH).

Both MHSWR and COSHH :

• Require risks to be assessed and prevented or, where this is not reasonably practicable, adequately controlled and ;
• Supported by Approved Codes of Practice that give additional information on the regulations and guidance and how to comply.

What you should consider :

• Can the risk of fire be prevented eliminated or reduced? If this is possible, it may be acceptable to adopt an alternative fire protection strategy such as sprinklers or detection and manual intervention.
• If a fire protection system is necessary, can a system be used that does not contain a hazardous substance, such as a water sprinkler system?
• If you decide that you require a system containing a hazardous substance or a system that creates a hazardous atmosphere in use, it may be possible to install the system in such a way that exposure of people to the agent is either prevented or minimised. Such controls would include switching the operation of the system to manual control whilst the protected area is occupied or installing a localised
  system such as an in-cabinet system.In some situations, such as those where there is a potentially rapid spread of the fire, an automatic system will be needed to protect an occupied space. In these situations, the system should be specified and designed in such a way that the atmosphere generated on discharge would not cause significant adverse effects on a normal healthy member of the population. The quantity of material used should be at the lowest level consistent with the efficient extinguishment of the envisaged fire. For these limited situations the potential risk from the extinguishing agent will need to be critically evaluated.

Checking your new System and Installer

The need to comply with the regulations related to the Montreal Protocol restricting the use of ozone depleting substances should not be allowed to jeopardise the safety of people and property that is provided by good fire protection practice.

Where standards for new systems are in the course of preparation, you are advised to use companies approved to ISO 9001 or EN29001 (BS5750 Part 1) for Design/Development of Fire Protection Equipment and System  Approval, or are able to show an equivalent level of competence.

To assist you in selecting alternative systems you should ensure that your suppliers,  advisers and installers:

• Can provide evidence of compliance with BSI/ LPCB/ NFPA standards or specifications, where these exist, relevant to the chosen system.
• Are using BS/LPCB/UL/FM/VdS listed or approved equipment wherever possible.
• Are accredited and listed to BSEN ISO 9000 QA system for manufacture.
• Are full members of a relevant Trade Association, (examples from the UK are FIA (BFPSA & FETA) or BAFSA. Similar organisations operate in other EU Member States).
• Comply with the UK Fire Industry Code of Practice (or equivalent).

Independent Approvals

One of the best ways to assess the fire fighting capability of an alternative system is to check what independent approvals it has obtained.

The following are generally considered to be among the leading independent approvals authorities:

Useful information

After a review of Regulation (EC) No 2037/2000 on substances that deplete the ozone layer, which started at the end of 2006, the Commission presented a proposal on 1 August 2008 which recasts and amends the current legislation.

• Environmental Protection Act 1990 – ISBN 0-10-544390-5
• Management of Health & Safety at Work Regulations Approved Code of Practice (1999) – ISBN 0-71-762 488-9
• Halons Technical Options Committee Reports
• Environment Act 1995 HMSO Publications Centre – ISBN 0-10-542595-8
• Control of Substances Hazardous to Health Approved Code of Practice (1999) – ISBN 0-71-761670-3

Categories:Miscellaneous Fire Safety Issues

March 17, 2011[Last updated: February 10, 2022]