Understanding Gaseous Fire-Extinguishing Agents

Gaseous fire-extinguishing agents are often used to effectively extinguish fires in special hazards that cannot be adequately protected by fire-sprinkler systems. These extinguishing agents are also utilized when the application of water may cause excessive collateral damage or an interruption of critical operations.

At one time, carbon dioxide and Halon were the common types of gaseous agents specified to protect special hazards from fire. Because Halon was identified as a stratospheric ozone-depleting substance, its production was banned in 1994 by the Montreal Protocol.

After the production of Halon was discontinued, the fire-protection community worked hard to develop effective extinguishing agents that do not harm the environment. Currently, more than 12 types of agents have been developed as alternatives to Halon. With all of these new gaseous fire-extinguishing agents in the marketplace, some important questions are being asked about protecting special hazards from fire:

1. What steps should be taken if an existing Halon extinguishing system is currently being used in a facility? Currently, there are no government regulations that require the decommissioning of existing Halon fire-suppression systems. And, recycled Halon is available to refill a system, if needed. This supply of recycled Halon will not last forever. As such, building owners should consider replacing Halon with an alternative agent in the near future.
2. Should carbon-dioxide extinguishing systems be considered to protect special hazards? Carbon-dioxide systems are very effective at extinguishing fires in most combustible materials. When used in total flooding applications (hazards that are enclosed), however, these systems produce lethal concentrations of carbon dioxide in the protected space. Consequently, carbon dioxide is not recommended for use as an extinguishing agent in normally occupied spaces.
3. What are the common types of gaseous agents that have been developed as alternatives to Halon? There are two common types of gaseous agents that are considered replacements to Halon: halocarbon compounds and inert gases. National Fire Protection Standard 2001: Standard on Clean Agent Fire Extinguishing Systems outlines the design, installation, and maintenance requirements for systems that employ these replacement agents.
4. Are these new alternative agents safe for building occupants and the environment? Although halocarbon and inert-gas extinguishing agents do pose health and safety risks, both types of agents are considered safe for use in normally occupied spaces when designed properly. Moreover, both types of agents are approved for use by the U.S. Environmental Protection Agency and don't deplete the ozone.
5. When a special hazard is required to be protected from fire, how can fire-protection engineers assist an owner? Fire-protection engineers understand the science and the latest technologies that are used to protect people, property, and the environment from fire. A fire-protection engineer can assist in determining the appropriate gaseous fire-extinguishing agent for the appropriate application and assist in preparing the design, installation, and maintenance requirements.

Chris Jelenewicz ([email protected]), a professional engineer, is the engineering program manager at the Society of Fire Protection Engineers, Bethesda, MD.