Halon has one of the higher ozone depletion potentials of any compound, and thus its production and use are being curtailed and eventually eliminated. The Montreal Protocol (1987 and subsequent) and the Clean Air Act Amendments (1990) identify Halon 1301 as a Class I ODS and established a ban on its domestic production effective 31 December 1993. Currently, halon use is restricted to recycled halon, which is estimated to be available until the end of Fiscal Year 2003.

In order for a substitute to be approved, it must pass certain requirements that are specific for each branch of the service. The requirements for the Army are: 1) US. Environmental Protection Agency's (EPA’s) Significant New Alternatives Policy (SNAP) approval, and 2) toxicology clearance from the Army Surgeon General. Both of these requirements must be approved for both the specific application as well as the specific alternative agent.

For the Air Force, the specific application and alternative agent must comply with AFI-32-7086 "Hazardous Materials Management", and must not impose a greater environmental or safety risk than Halon 1211. If the application is questionable, it must undergo an environmental safety and occupational health evaluation.

The Navy’s requirements are: 1) SNAP approval and 2) An ozone-depleting potential (ODP) for the alternative of 0.05 or less (OPNAVINST 5090.1B, "Environmental and Natural Resources Program Manual" 1 November 1994).

In addition to these requirements, the applicable program office (for a weapon system) or fire chief (for an installation) will have regulations and directives that must be satisfied before substitutions are made. Ultimately, it is up to the program office or fire chief to make the substitution, not the user.

Several substitutes have been approved by the SNAP program that may be considered as potential candidates for specific use conditions as cited in 40 CFR 82 Appendix A to Subpart G, Substitutes Subject to Use Restrictions and Unacceptable Substitutes. It should be noted that the following substitutions are merely comments on usage and not conditions. For example, the Army has considered the use of HFC-125 in the crew compartments of its ground combat vehicles. Also, the Army has installed IG-541 in normally occupied areas. The following substitutes are listed:

Total Flooding Agents Acceptable Substitutes

• Water Mist Systems using Potable or Natural Sea Water
• [Foam] A (formerly identified as Water Mist Surfactant Blend A) This agent is not a clean agent, but is a low-density, short duration foam.
• Carbon Dioxide (Must meet NFPA 12 and OSHA 1910.162(b)5 requirements
• Water Sprinklers

Total Flooding Agents Substitutes Acceptable Subject To Use Conditions

Normally Occupied Areas

• C4F10 (PFC-410 or CEA-410)
• C3F8 (PFC-218 or CEA-308)
• HCFC Blend A (NAF S-III)
• HFC-23 (FE 13)
• HFC-227ea (FM 200)
• IG-01 (Argon)
• IG-55 (Aragonite)
• HFC-125
• HFC-134a

Normally Unoccupied Areas

• Powdered Aerosol C
• CF3I
• HCFC-22
• HCFC-124
• HFC-125
• HFC-134a
• Gelled Halocarbon/Dry Chem. Suspension (PGA)
• Inert Gas/Powdered Aerosol Blend (FS 0140)
• IG-541 (Inergen)

Unacceptable Substitutes

• HFC-32

Although there are a number of approved alternatives to Halon 1301, it is critical that any alternative’s applicability be verified, given the long list of qualifications and use conditions to which each alternative is subject. This wide variation in use conditions is mainly a result of physical property differences. Some of these compounds are not as effective in extinguishing a fire, and so a higher concentration of the gas is required. High gas concentrations also increase the sensitivity of personnel to cardiotoxicity and reduce available oxygen content. As a result, many of the use conditions require personnel evacuation in 30 seconds or less, a critical and sometimes impossible requirement to meet. Each alternative for any application should be carefully reviewed for applicability to the Use Conditions. The following presents some advantages and disadvantages of several alternatives:

• FM-200 (HFC-227) can be used in occupied and unoccupied areas and has the lowest global warming potential and zero ozone depleting potential. FM 200 is the most commercially available agent. The cylinders must be located in, or adjacent to a protected area and the design concentration in occupied areas must be limited to 7% to 9%. This alternative cannot be piped over long distances, and its low boiling point means the agent must be stored in a controlled environment.
• FE-13 (HFC-23) has no EPA restrictions, NOAEL of 30%, typical design concentration of 16-20%, zero ozone depleting potential and is gaining commercial availability. It requires use of high pressure storage cylinders and piping.
• INERGEN (IG-541) can be used in unoccupied areas, although there is no prohibition against its use in occupied areas. It has little or no environmental drawbacks because it uses normal atmospheric gases (N₂, Ar and CO2). Although it lowers oxygen levels under 16%, tests have indicated that healthy individuals can function unimpaired at oxygen levels of 12%, and CO₂ is added to the mixture to facilitate hyperventilation. The system requires high pressure cylinders and large volumes stored as a gas, not a liquid.
• SPRINKLERS are usually mandatory even with an alternate clean agent (i.e., gaseous extinguishing systems). Sprinklers are not recommended below raised floors. Sprinklers are both the cheapest and simplest alternative. They have already been implemented in computer facilities and should be considered for housed electronics systems which have the ability to deactivate power before sprinklers are engaged.
• CO2 is a good inexpensive agent for use below computer room raised floors. For use in unoccupied areas only.

Since none of the SNAP-approved alternatives for Halon 1301 are direct "drop-in" replacements for Halon 1301 systems, especially those for normally occupied areas, an engineer who is experienced in fire protection system design should be consulted. Larger military bases may have one of these engineers on the public works/civil engineering staff. Some bases, especially smaller bases, may have to enlist the services of another military engineering organization/engineering contractor. For Navy commands, the local Naval Facilities Engineering Field Division, Engineering Field Activity, or Navy Public Works Center can provide these services.

Several steps must be taken in order to provide a suitable substitute for Halon 1301:

1. The first step is to identify a need for fire suppression.
   
   
2. The next step is to identify fire suppression requirements. The first requirement is to determine what types of fires are most prominent in the area (A, B, and/or C). The second is to identify where and how often these fires occur. The third requirement is to determine what kind of response is needed (manual or automatic). Once these requirements have been met, then a suitable substitute may be identified.
   
   
3. The third step is to find the cheapest and easiest solution. This will vary from application to application. However, approximately 90% of the applications should be capable of converting to water sprinklers, which are 25-33%of the cost of alternative gaseous agents.

When conducting a risk assessment, a fire protection engineer will consult MIL-HDBK-1008C Military Handbook On Fire Protection For Facilities Engineering, Design, and Construction, appropriate National Fire Protection Association (NFPA) standards, and additional service specific guidance. It is important to note that MIL-HDBK-1008C has no requirements for the use of Halon 1301 in fire protection system design for facilities.

Army personnel may consult DA-Pamphlet 385-16 System Safety Management Guidance, AR 385-16 System Safety Engineering and Management and the AAPPSO Strategic Guidance and Planning for Eliminating ODCs from U.S. Army Applications. The Army has successfully Beta tested the Halon Alternatives Selection Tool (HAST). HAST is a software tool that allows the user to input data about an existing halon installation and it will provide recommended alternative system options with estimated costs.

Navy personnel may consult the Naval Facilities Engineering Command Shore Facilities Ozone Depleting Substances Conversion Guide.

Air Force personnel may consult HQAFCESA Engineering Technical Letter (ETL) 95-1: Halon 1301 Management Planning Guidance, ETL 93-5: Fire Protection Engineering Criteria - Electronic Equipment Installations, and ETL 94-6: Fire Protection Engineering Criteria - Removal of Halogenated Agent Fire Suppression Systems.

In the majority of facility applications where Halon 1301 is in use, automatic water sprinklers are the preferred alternative for fire protection. In numerous facilities, the spaces presently protected by total flooding Halon systems are also protected by automatic sprinklers. In many of these areas, removal of the Halon without replacement or removal and replacement with additional portable fire extinguishers is adequate since the area is already protected by automatic sprinklers in accordance with MIL-HDBK-1008C. If automatic sprinklers are not already installed, then installation of automatic sprinklers will be the most likely preferred alternative protection option. Some commercial facilities have also installed additional smoke/fire detectors to provide early warning to building occupants, thus allowing a quick local first response to a small fire with portable extinguishers.

There are cases where automatic sprinklers are not the preferred alternative or cannot be used, however these cases are the exception and not the rule. Some of these cases are:

• Computer room under floor spaces which require fire protection because the data cable is not plenum rated and/or the power cable is not in conduit. Automatic sprinklers are not appropriate for under floor spaces because conventional nozzles cannot be placed for full coverage in these cramped spaces. In under floor spaces, a carbon dioxide system or other gaseous alternative agent (halocarbon or inert gas) should be used. It is important to note that an under floor space is not considered an occupied area, even if the space above the floor is normally occupied.
• In areas where an adequate water supply is not available. This situation often arises when the area is a remote building or the entire facility is in a remote area such as the Pacific Islands or the Arctic. In these situations carbon dioxide may be used for unoccupied areas or an alternative gaseous agent may be used for normally occupied areas.
• In areas which are determined by the local military commander to contain equipment of such high value or strategic importance to the military mission that damage or interruption of operations is considered to be unacceptable. Examples of these areas might include certain command and control centers, areas housing supercomputers used for data processing of important information for combat systems targeting and/or navigation, or facilities housing high value flight/combat simulators. In these areas, the use of a gaseous Halon alternative agent (halocarbon or inert gas) may be appropriate.

Halon 1301 for use in mission critical applications is supplied by DLA from the Defense ODS Reserve. Procurement of Halon 1301 for any other uses requires a certification by an authorized technical representative (ATR) and approval by a senior acquisition official (SAO) at the flag/general officer or civilian SES level in accordance with the specific Service guidance implementing this law, Section 326 of the FY-93 Defense Authorization Act which is also identified as Public Law 102-484. Furthermore, excess Halon 1301 removed from non-mission-critical applications should be returned to the Defense ODS Reserve in accordance with Service procedures. Further information on return procedures can be obtained from Defense Supply Center, Richmond at (804) 279-4525/5203.

There are no direct drop in substitutes for Halon 1311. Thus, the economic feasibility for using a Halon 1311 substitute is highly dependent on the application. Total flooding systems normally consist of a fixed supply of the Agent connected to piping with nozzles to direct the agent into the hazard area. There are many factors that can affect the cost of using Halon 1311 alternatives. These include:

• The volume of the space to be protected,
• The type of equipment protected, and
• The ability to use existing delivery, actuation and alarm systems.

The following is an example of a retrofit with a Halon 1301 replacement. The Memphis Detachment of Carderock Division, Naval Surface Warfare Center (CDNSWC) had an accidental Halon 1301 fire-suppression discharge in the Data Acquisition Analysis System (DAAS) computer room. The room size is 20 ft x 22 ft x 10 ft high (approx. 4400 ft³.). It was decided that instead of refilling the Halon 1301 system, a conversion to a zero-ODP alternative agent would be pursued. The facility selected an Inergen fire suppression system as the long term most cost effective method to restore fire protection. Inergen is a mixture of Nitrogen (52%), Argon (40%), and Carbon Dioxide (8%). The components are mixed by local compressed gas cylinder companies and supplied at a cost of approximately $0.25/ ft³.

Replacement with Inergen required new pressurized gas cylinders, slight piping modifications and a replacement of the fire suppression nozzles. The single 123 lb. Halon cylinder was replaced with four 350 cubic ft cylinders. To prevent future accidental releases, it was decided to replace the Heat/Smoke detectors with ones which will not be affected by moisture. A contract for the system changeout and detector modifications was awarded for $5,525.70.

In the event of future releases, refilling the Inergen cylinders should cost $350.00 (350 ft³ cylinder x 4 = 1400 ft³ x $0.25/ ft³) excluding labor and any other miscellaneous materials verses $3,936.00 to refill with Halon 1301 (123 lbs x $32.00/lbs.) or less than 10% of the cost to refill with Halon 1301.

The following are some general cost analyses for various fire protection scenarios.

• All examples assume that there is enough storage space for the large volume cylinders required for implementation of Inergen (3-5 times the space required for FE-13 or FM-200).
• Examples are for a complete installation. If components such as detectors, alarms, and other minor components from an existing halon system can be reused, then costs may decrease by $2K-$5K or more.
• These costs reflect initial cost only. When making decisions on selection of agents, accidental discharges and other life cycle costs should be considered. For example, if a system is estimated to discharge once over the 20 year life of the system, then a more expensive Inergen system (initial cost) will actually be cheaper over the life cycle than lower initial cost FM-200 or FE-13 system.
• Assumes that a water sprinkler system could not be used. In many cases water sprinklers are the most appropriate alternatives. Water sprinkler systems typically cost less than gaseous alternative agent systems (Both life cycle and initial costs). A typical cost for a water sprinkler system in a 5000 ft3 space might range from $2K (wet pipe with standard detection) to $10K (preaction with early detection).

The following presents some estimated costs for installing Halon 1301 alternative fire suppression systems:

Example 1: Computer/Telecommunications area (3,000 ft3)
Inergen: $11,900
FM-200: $10,700
FE-13 $10,500 (Not recommended due to high GWP of HFC-23)

Example 2: Computer/Telecommunications area (5,000 ft3)
Inergen: $16,000
FM-200: $14,300
FE-13: $13,600 (Not recommended due to high GWP of HFC-23)

Example 3: Computer/Telecommunications area (8,000 ft3)
Inergen: $22,000
FM-200: $19,600
FE-13: (Not recommended due to high GWP of HFC-23)

Example 4: Flammable Liquid Handling Area (5,000 ft3) - Cylinders located in unprotected arctic temperatures (-40 degrees F)
Inergen: $18,600
FM-200: Not feasible
FE-13: $15,700

Example 5: Diesel Engine Equipment Area (10,000 ft3)
Inergen: $24,000
FM-200: $21,400
FE-13: $19,800

Facilities Halon 1301 total flooding fire suppression systems usually have no real expected service lives. Their components are simplistic and durable enough to last virtually forever.