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Halon 1301 has been the preferred means of fire protection in computer and electronic data processing areas since the 1960s. However, its long-term future is in question because of its classification as a chlorofluorocarbon (CFC)'identified as a contributor to depletion of the earth's stratospheric ozone layer, the planet's shield from ultraviolet radiation. Consequently, the Montreal Protocol of 1987 and subsequent Copenhagen amendments banned the production of additional Halon 1301 (except in less developed countries and for some 'exceptional use' exemptions) beginning in 1994.

Thus, the challenge for today's risk managers and fire protection professionals is to identify the best halon protection substitute for each area requiring protection. The recommended method of identifying the best alternative is to employ an 'engineered approach' based on an individual case analysis. This evaluation of alternatives is most effectively performed by involving qualified consultants early in the decision-making process. The key characteristic sought by the risk control professional is for the halon substitute to have sufficient fire suppression ability for the application without harming the environment and human health. This article will identify and evaluate the available alternatives to help companies choose the best protection methods for meeting their future fire protection needs.

Halon 1301 Status

While production of Halon 1301 was banned, effective January 1, 1994, the use and sale of Halon 1301 were not prohibited. Presently, there are no requirements to remove existing systems or limitations placed on new installations. Furthermore, should a halon system leak or discharge agent, there are no penalties, fines, or taxes in place.

The reasons for the widespread use and acceptability of halon are:

  • Halon 1301 is a clean agent not requiring cleanup after discharge.
  • Halon is electrically nonconductive and not detrimental to computer hardware or other sensitive electronic equipment.
  • The agent is not hazardous to people in typical concentrations used (less than 10%).
  • The agent is very effective and fast-acting in controlling fire propagation.

Although Halon 1301 remains an effective means of controlling fires in electrical occupancies, environmental concerns may result in the enactment of regulations in the future. Additionally, corporations may wish to consider fire protection choices from a public relations perspective. Corporations considered 'environmentally correct' may be viewed more favorably by potential customers.

For many current halon users, the Montreal Protocol regulations have not affected them at all. Many facilities with existing halon systems have simply opted to leave them in place, with the exception that if a discharge were to occur, the agent would not be replaced. This strategy is fine for now, but obviously, provisions must be made for the future. As alternative agent research continues, manufacturers are offering users increasingly improved and diverse choices for protection.

It is also apparent that a large portion of the halon market will not return; i.e., many users will either do without halon and/or alternative agents or opt for a different method altogether, such as sprinklers. Many in the industry have acknowledged the obvious: halon was in effect 'oversold' to customers. In other words, even before the ban, there were more appropriate choices for certain protection applications, but they were not fully explored. The halon ban thus unintentionally resulted in more research and choices of protection methods. Additionally, fire protection experts acknowledge that the network servers and personal computers that replaced the large mainframe computers of the 1960s and 70s are less costly to replace.

There is no perfect substitute for halon, although research dollars continue to be poured into the search. Of the current alternatives, compromising factors including cost, weight, size, and environmental and health risks. Several substitute gases are available and approved by the EPA for use in occupied spaces, such as electronic data processing rooms. In addition, other methods have received attention as viable alternative protection approaches. These include:

  • Banked Halon 1301
  • Pre-action sprinklers/below-floor CO2
  • Duplication of critical equipment
  • Fine mist water spray
  • 'Essential-use' exemptions

The advantages and disadvantages of these options are discussed below. It should be noted that Halon 1211, used in portable extinguishers, is also a CFC and is affected by the ban. However, the need for a replacement is not as critical to a corporation from a risk control standpoint. Most users of 1211 extinguishers should simply replace them with another choice such as dry chemical or carbon dioxide. Halon replacement choices are also available, including Dupont's FE36.

Banked Halon 1301

Halon 1301 remains an effective means of suppression and can still be purchased through stored banks of the agent and recycling of systems removed from service. However, effective January 1, 1994, all Halon 1301 held for sale has been subject to an 'excise tax' imposed by the Internal Revenue Service (IRS). This 'floor stock tax' is $58.00 per pound in 1996 and has increased to $62.50 per pound in 1997. Although recycled Halon 1301 will not be taxed, the recycling costs themselves and naturally rising prices associated with a limited supply, could significantly raise the cost of recycled halon as well.

Currently, banks of Halon 1301 are maintained by:

  • National organizations, such as the Halon Recycling Corporation;
  • The United States Military, Department of Defense;
  • Internally within corporations and organizations;
  • Local fire equipment vendors, and;
  • Share agreements between countries.

As noted, the price of banked and recycled Halon is expected to fluctuate with supply and demand. The world total of banked Halon 1301 is estimated at 130 million pounds, approximately fifty-seven million pounds of which is estimated to be in the United States. The largest customer so far has been the U.S. military for mission-critical areas on ships and in military equipment.

Most companies that choose to stay with Halon 1301 do so because halon fits a distinct need that no other alternative will meet. Therefore, the advisability of purchase should be evaluated in the context of the other alternatives presented here and the high probability of increasing restrictions on use and disposal of Halon 1301. As noted earlier, corporations may also wish to consider the impact of negative publicity associated with the use of an agent harmful to the environment.

A good 'rule of thumb' is if a well-designed Halon system is already in place, keep it for now. Institute a contingency plan to stock enough banked halon to replace a discharge. Larger corporations should consider setting priorities by ranking their systems and even eliminating non-critical systems by converting to an alternative, such as sprinklers. These simple strategies should buy a corporation enough time to allow the alternative agent markets to better develop and insurance companies to find a comfort level with other protection.

Replacement Agents

Research by leading chemical and fire protection equipment manufacturers has resulted in the development of several alternative agents to Halon 1301. However, except for the hydrobromofluorocarbons, the alternative agents are less effective than Halon 1301. Additionally, larger volumes of agent are needed, often two to three times as much. In other words, no 'drop-in' replacement has been developed to date. Extensive research continues to develop better halon replacements and alternatives.

All of the agents have been evaluated in accordance with the process used by the U.S. Environmental Protection Agency's Significant New Alternatives Program (SNAP). The most common in-kind halocarbon replacements to date are HFC-227 (FM200), HFC-23 (FE13), and CEA-410. FM200, manufactured by Great Lakes Chemical, was intended to closely model halon, and is an effective, if not 'drop-in,' substitute. Dupont's newer FE13, a high-pressure agent, is another choice tailored for data processing areas. The accepted standard and guideline for halon substitutes and the design and installation of systems is the National Fire Protection Association's Standard 2001, 'Clean Agent Fire Extinguishing Systems,' 1996 edition. This document also contains minimum requirements for the design, installation, testing, inspection, operation, and maintenance of systems containing gaseous agents developed after the Montreal Protocol was signed.

The eight new clean halocarbon agents addressed in NFPA 2001, which are also included on the EPA's SNAP list are:

FC-3-1-10 (CEA-410),


HCFC-124 (FE-241),

HFC-125 (FE-25),

HFC-227ea (FM200),

HFC-23 (FE-13),


and FIC-1311.

The three inert gas agents listed in NFPA 2001 are: IG-01 (argon), IG-541 (Inergen), and IG-55 (nitrogen/argon blend).

Although obviously not in the category of new technology, inert gases have gained in favor since they have no negative impact on the environment. They also produce very little acid gas products during fire suppression, decreasing possible damage to sensitive electronic equipment. Since inert gases rely on diluting oxygen in the atmosphere to suppress a fire, the negative impact on life safety is a concern. Another negative aspect is the need for large volumes of gas and the accompanying heavy high pressure tanks to store them.

Pre-action Sprinkler System

Since the halon ban, pre-action sprinkler systems have become the preferred choice for protection in computer rooms. Most Highly Protected Risk, or 'HPR' insurance carriers are now recommending pre-action systems for new computer installations. Although halon alternative agents are still an option, many are choosing a pre-action system instead, especially if sub-floor protection is not needed. A pre-action system is simply an ordinary sprinkler system designed to avoid unnecessary water damage. The system piping is maintained dry through a valve that holds back water from the sprinkler lines until two (2) cross-zoned detectors electronically signal the valve to trip, presumably in a fire scenario. Depending upon the intensity of the fire, the fusible link-operated heads will open as necessary to control the fire. Design parameters recommended for most systems are:

  • Sprinklers should be 1/2 inch orifice, 165 degree F-rated pendant-type heads.
  • Sprinklers should be hydraulically designed to provide a density of 0.15 gpm/sq. ft. over the most remote 2,000 sq. ft. area.
  • Sprinkler piping should be galvanized Schedule 40, utilizing screw-type fittings.
  • The fire detection system should be one of the following types: hydraulic rate-of-rise, pneumatic rate-of-rise, or electric.

Factory Mutual's Approval Guide lists seven manufacturers of approved systems. Electrically operated pre-action systems are approved on a component basis.

Carbon Dioxide Below Raised Floor

To provide protection and early warning of a fire in grouped electrical cables beneath raised floors, total flooding carbon dioxide is recommended in conjunction with ceiling level pre-action sprinklers. In general, the following parameters should be used:

  • The system should be designed to provide a 50 percent concentration of carbon dioxide beneath the floor for 20 minutes to allow for deep-seated fire conditions.
  • Air handling systems should be interlocked to shut down upon activation of the system.
  • Carbon dioxide agent should be discharged by actuation of two (2) cross-zoned detectors beneath the raised floor.
  • Capacity for an initial discharge with connected reserves should be provided.

The advantage of a pre-action sprinkler/CO2 subfloor system is:

  • The systems are not subject to current or future environmental restrictions.
  • In addition to data processing equipment, many computer rooms contain ordinary combustibles such as printing paper and tape storage. Water is a more effective method than halon in controlling fires in moderately combustible environments.

Fine Mist Water Spray

The halon production phase-out described above precipitated immediate exploration of alternative technologies. One of these, 'Fine-Mist Water Spray' technology, has generated much interest globally as a potential replacement for halon and CO2 systems.

A water mist system is a fire protection system using very fine water sprays, i.e., 'water mist.' The very small water droplets allow the water mist to control or extinguish fires by a combination of flame cooling by droplet vaporization, oxygen concentration reduction by steam production, and cooling at the burning surface similar to conventional sprinklers.

Water mist technology disperses very small (less than 1000 microns) water droplets. These droplets use far less water than a conventional sprinkler system, only about 10 gallons (3.8 liters) per 1,000 cubic feet (twenty-eight cubic meters). The potential for less water damage is particularly beneficial in occupancies such as data processing centers and telephone central offices. Conversely, water mist systems cannot be used for direct application on materials that react with water to produce violent reactions or hazardous byproducts. Some examples are: reactive metals such as titanium, magnesium, and uranium; carbides (calcium carbide); hydrides (lithium aluminum hydride); and metal amides, such as sodium amide.

Research and testing by interested parties, including the Factory Mutual Engineering Association and the Society of Fire Protection Engineers, suggests that water mist technology offers several advantages over conventional water systems, especially in applications where environmentally friendly technology is desirable. Some applications currently being considered in the Factory Mutual research program include: gas turbine enclosures, marine applications, light hazards and local applications, flammable liquid handling, telephone central offices, and computer clean rooms. The advantages include:

  • Water mist system is relatively low in cost compared with gaseous agents.
  • Water is non-toxic, thus harmless to the environment.
  • Water flow rate required by water mist technology is significantly less than that required by a conventional sprinkler system, thus reducing water damage.
  • Water mist systems can be activated by a variety of means.

Several disadvantages of a water mist system include:

  • Difficulty in extinguishing deep-seated Class A fires and shielded/obstructed fires.
  • Dependence upon electrical power to operate the water pumping system, thus making it vulnerable to impairment.
  • Lightness of the mist'gravity tends to dissipate the droplets, diluting their concentration and ability to reach obstructed areas. (On a positive note, fires not extinguished by the mist systems are usually still controlled, with the surrounded space cooled and the structural integrity protected.)

Water mist system design and installation parameters are detailed in the National Fire Protection Association's new standard, NFPA 750, 'Standard for the Installation of Water Mist Fire Protection Systems,' 1996 edition. Detection, actuation, alarm, and control systems, are all in accordance with existing NFPA guidelines. The fine spray water delivery system is similar to a conventional sprinkler system with several key differences, including:

  • Water delivery Water is delivered under high pressure or atomization to deliver significantly smaller droplets than a sprinkler system.
  • Nozzle design Nozzle orifices are smaller to support the atomization at high pressure.
  • Water flow requirements Preliminary information suggests that the smaller the droplet size, the lower the flow requirements and the less water damage experienced.

Water mist hardware manufacturers include such well-known traditional sprinkler companies as Grinnell, Reliable Automatic Sprinkler, and Kidde/Fenwal. Many others are still in the research & development phase. System design is usually based on two approaches: 'twin fluid' and 'high momentum pressurized water.' The twin fluid approach was developed and reviewed by the Factory Mutual Engineering Association along with several companies listed above.

Twin fluid technology uses compressed air or nitrogen, blended with water at the nozzle to make droplets. Relatively low water pressures are needed, around 75 psi; the design is particularly favored for gas turbine and engine room protection. Factory Mutual's approval process is continuing for occupancy-specific water mist system designs. To date, only the Securiplex Corporation of Canada has received approval for a fine water spray system. FM's approval is specifically for the protection of 'gas turbines in enclosures in volumes up to, and including, 2825 cubic feet.'

'High momentum pressurized water' design research is being driven by the need for protection in large military applications. These include marine passenger and military ship lodging areas and airplane passenger compartments. Although research has been done for computer and electrical room applications, the high water pressure required (between 500 and 4200 psi) limits the use of this technology for most corporate needs.

In short, water mist systems are still best considered only for niche-type applications. Until more data is gathered and evaluated, a water mist system should be considered only through close consultation with the property insurance carrier and loss control professionals. Most authorities predict a specific design standard, endorsed by HPR insurance companies and the National Fire Protection Association, is at least a year away.

Fine Particulate Technology

Fine particulate technology uses a chemical reaction to generate fine solid and liquid particulates dispersed in an enclosure to extinguish a fire. The primary method of suppression is gas-phase cooling. These systems are also known as 'combustion-generated aerosols,' or 'pyrotechnically generated aerosols.' This technology is still in its infancy, but continues to be well funded, particularly by military interest groups.


Duplication of critical equipment at a separate location may also be considered. Providing duplication is a common risk management technique for reducing business interruption potential associated with the loss of critical equipment. Unfortunately, in many circumstances, full duplication will not be economically feasible. A risk manager's determination whether to provide duplicate critical equipment capabilities as an alternative to halon is most accurately made following a hazard identification and business impact review. The identification of critical equipment, including data processing systems, and the impact of loss to the corporation is the first step in the contingency planning process. Once these critical areas are identified and the impact of loss to the corporation is quantified (in dollar-value loss expectancy), a decision is made more easily. In fact, many contingency plans include provisions for a 'hot/warm' site to set up electronic data processing operations in an emergency. 'Hot/warm' sites are essentially 'duplication' of critical equipment and may be an adequate back-up plan for loss of a critical area even without additional fixed protection. Usually, however, if the loss impact justifies a back-up emergency site, fixed protection should be considered.

Essential-use Exemptions

Several organizations under the auspices of the United Nations Environment Program are responsible for the review and approval of essential-use exemptions. Although there is yet no clear indication of what is considered an 'essential-use' exemption, clearly the submittal and review process is lengthy and strict with the eventual outcome uncertain. The following criteria must be met in order for an exemption to be granted.

  • The necessity of the exemption for health, safety, or criticality of function must be justified.
  • There must be no other technically or economically feasible alternative available.
  • Halon must not be available from existing stock or banks.
  • All economically feasible steps must have been taken to reduce essential use.

As a result of these stringent requirements, the essential-use exemption alternative is not recommended. However, if a particular situation appears to meet the above criteria, the option is available. If pursuit of this option is desired, the process would begin with a submitted request to a national government and an eventual review by the Halon Technical Options Committee, Technology and Economic Assessment Panel, the Open-Ended Working Group, and finally, the parties to the Montreal Protocol. All of these organizations are sponsored by the United Nations Environment program.


Since the production ban on Halon 1301 in developed countries in 1994, the urgency for halon substitutes and alternative protection methodologies has increased dramatically. While none of the protection options available today are the perfect replacement for Halon 1301, new alternatives continue to be explored. Several agencies, including the U.S. Department of Defense, continue to develop plans and options for fire suppression on ships, combat vehicles, and aircraft. Private industry will benefit from these research projects. These future solutions will present new and improved alternative agents and technologies. In addition, we will likely see better methods of analyzing hazards under different fire scenarios, earlier means of fire detection, and faster response of suppression.

Meanwhile, risk managers and fire protection professionals must evaluate the available alternatives and decide the best protection solutions on an individual case-by-case basis. Many agree the qualities of halon were not fully appreciated until the ban. Risk managers and former halon users should thus be prepared to compromise on cost and effectiveness when selecting an alternative to halon.


NFPA 2001, 'Standard on Clean Agent Fire Extinguishing Systems' (1993), Standard on Clean Agent Fire Extinguishing Systems and F93-PCR, National Fire Protection Association, Quincy, Massachusetts.

J.A. Senecal, 'Halon Replacement Chemicals: Perspective on the Alternatives,' Fire Technology, National Fire Protection Association, Vol. 28, No. 4, 1992, pp. 332-344.

DiNenno, P.J., 'An Overview of Halon Replacements and Alternatives,' Proceedings of Advances in Detection and Suppression Technology, SFPE Engineering Seminars, San Francisco, CA, 1994, pp.21-31.

NFPA 2001, Standards on Clean Agent Fire Extinguishing Systems, National Fire Protection Association, Quincy, MA, 1994 edition, pp. 238-277, and 1996 edition.

NFPA 12A, Standard on Halon 1301 Fire Extinguishing Systems, National Fire Protection Association, Quincy, Mass., 1992 edition.

'Global Environmental Characteristics of Second-Generation Halon Replacements,' Proceedings of Halon Alternatives Technical Working Conference, Albuquerque, NM, 1993, pp.31-36.

Joseph Z. So, Andrew K. Kim, and Jack R. Mawhinney, 'Review of Total Flooding Gaseous Agents as Halon 1301 Substitutes,' Journal of Fire Protection Engineering, 8(2), 1996, pp. 45-64.

Factory Mutual Approval Guide, 1996 edition.


Yvonne M. Keafer, P.E., ARM, is an assistant VP in the Pittsburgh office of Sedgwick of PA, Inc. She is a voting member of the National Fire Protection Association Committee on Disaster Planning, NFPA 99.