Halon
alternatives
NFPA 2001: Standard on Clean Agent Fire Extinguishing Systems
Critical facilities require fire protection systems which can detect and suppress fires quickly without harming equipment, the facility, or the environment. Gielle Clean Agent systems offer the best way to meet this challenge by discharging an environmentally friendly agent in less than 10 seconds, leaving no harmful residue to clean up.
Gielle Fire Systems offers various types of clean agent systems for a variety of applications:
Clean agent fire suppression systems
NFPA 2001, "Standard on Clean Agent Fire Extinguishing Systems" defines a
"Clean Agent" as an "electrically non-conducting, volatile, or gaseous fire extinguishant that does not leave a residue upon
evaporation."
Gielle is the acknowledged industry expert on buying, selling and recycling Halon and other Clean
Agents.
In response to the ban on Halon 1301 manufacture, the fire suppression industry has responded with the development of alternative clean agents that pose less of a threat to the ozone
layer. Two classes of agents have emerged as suitable replacements: halocarbon-based agents and inert gas
agents. The halocarbon-based agents are carbon-based compounds and extinguish fire primarily via the absorption of
heat. Inert gas agents are based on the inert gases (i.e., nitrogen, argon, carbon
dioxide) and extinguish fire via oxygen depletion.
Clean Agent Fire Extinguishing:
NFPA 2001: Standard on Clean Agent Fire Extinguishing Systems
NFPA® 2001, "Standard on Clean Agent Fire Extinguishing Systems" defines a "Clean Agent" as an "electrically non-conducting, volatile, or gaseous fire extinguishant that does not leave a residue upon evaporation."
Production of Halon 1301, the gold standard Clean Agent, ceased in 1994 in line with the Montreal Protocol. Today, recycled Halon 1301 is still the most effective and inexpensive clean firefighting agent available, and it is low in toxicity. Halon alternatives like HFC-227ea are also widely used. Gielle is the acknowledged industry expert on buying, selling and recycling Halon and other Clean Agents.
In response to the ban on Halon 1301 manufacture, the fire suppression industry has responded with the development of alternative clean agents that pose less of a threat to the ozone layer. Two classes of agents have emerged as suitable replacements: halocarbon-based agents and inert gas agents. The halocarbon-based agents are carbon-based compounds and extinguish fire primarily via the absorption of heat. Inert gas agents are based on the inert gases (i.e., nitrogen, argon, carbon dioxide) and extinguish fire via oxygen depletion.
With the advent of the new clean agents, businesses worldwide will continue to have the ability to protect critical equipment and irreplaceable items, despite the ban and inevitable disappearance of Halon 1301 from the marketplace. With the mandated decommissioning of Halon 1301 in the EC and the increasing pressure from governments worldwide to reduce dependency on ozone depleting substances, it is expected that the future will see an increased utilization of Halon alternative clean agents.
Although the Halon 1301 alternatives are only approximately 70% as effective as Halon 1301 at extinguishing fires, the alternatives have similar characteristics. Like Halon 1301, the new agents are clean (i.e., they leave no residues following extinguishment). As a result, no cleanup is required after discharge of the agents. Because the agents form no corrosive or abrasive residues they are suitable for use on delicate, expensive assets that might otherwise be destroyed by non-clean agents such as foam or water (e.g. books, paintings, cultural heritage items). The clean agents are non-corrosive and non-conductive, and hence can be employed for the protection of sensitive electrical and electronic equipment. Most of the new agents are nontoxic at their typical design levels, and hence are acceptable for use in occupied areas. The clean agents are gases, and can thoroughly flood a protected area, affording rapid extinguishment of even obscured or hard to reach fires. The clean agent systems are applicable to Class A, B and C fires. When coupled with an early detection system, clean agent systems provide rapid extinguishment, reducing equipment damage and ensuring the safety of personnel within the fire area.
Appearance-wise, clean agent systems are similar in many aspects to Halon 1301 systems, although, in general, none of the clean agents can serve as a complete drop-in replacement for Halon 1301: all require modification to the piping systems and or nozzles and system cylinders. Halocarbon agents are stored as compressed liquefied gases, and systems are typically super pressurized to 25 or 40 bar with nitrogen, with the exception of FE-13, which does not require super pressurization. Inert gas agents are supplied in high-pressure gas cylinders, typically pressurized to 200 or 300 bars. For both halocarbon and inert gas systems, additional system components include the usual collection of selector valves, piping, and
nozzles.
Phase out of Halons
Introduction
Under the Montreal Protocol Halon 1301, Halon 1211 and Halon 2402 is in developed countries illegal with the following exceptions.
Use of Halon 1301 will 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 centre's 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 will be 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.
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.
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 CO 2 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 phase-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 thing 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 CO 2 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.
International halon bank
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