Clarifying Clean Agents

CONSULTING-SPECIFYING ENGINEER: What is the status of Halon phase-out in the United States? RIVERS: All production of halon in the United States ceased in the early 1990s after the U.S. signed on to the [1987] Montreal Protocol. The transition to alternative means of clean-agent fire-protection has reportedly gone quite well, with the introduction of inert gas fire-protection systems and hydr...

By Jim Crockett, Editor-in-Chief and Barbara Horwitz, Contributing Editor January 1, 2003

CONSULTING-SPECIFYING ENGINEER: What is the status of Halon phase-out in the United States?

RIVERS: All production of halon in the United States ceased in the early 1990s after the U.S. signed on to the [1987] Montreal Protocol. The transition to alternative means of clean-agent fire-protection has reportedly gone quite well, with the introduction of inert gas fire-protection systems and hydrofluorocarbons (HFCs) as interim solutions.

ENGLER: All new installations are using the new technologies and some end users are proactively converting existing Halon systems. But unlike the European Union, the U.S. does not have a “use” phase-out for Halon, so there is a need to increase end-user awareness of the environmental impact from Halon and the improved performance of the alternative systems. We also believe the EU’s mandated phase-out by the end of 2003 will facilitate a broader upgrade to today’s state-of-the-art fire-suppression technology.

RIVERS: I think the U.S. could take the same action as the EU, now that there is evidence of a responsible transition program. Companies are currently positioned to replace and destroy the Halon. We’ve certainly gone this route with the fluoroketone technology we’ve developed for both flooding and streaming, that we think provides a sustainable technology at a time when Europe is focused on establishing rules for managing emissions of HFCs and PFCs (perfluorocarbons)—both identified as global warming gases by the Kyoto Protocol.

VARLEY: Our experience has been to the contrary: Halon phase-out is rarely undertaken as a programmed replacement of obsolescent systems. Rather, when there is a loss of agent through discharge or leakage, determinations are made on an individual basis whether to recharge the system using secondary market Halon [where it is recovered from existing or older equipment, recycled and then sold], installing an alternative clean-agent system, installing sprinkler protection or eliminating protection altogether. The problem, in my eyes, is there are no objectives or expectations to stop the use of existing Halon systems or to collect Halon for safe disposal. Thus, over a considerable time, it’s possible all existing Halon gas will ultimately be discharged to the atmosphere.

CSE: For the record, what are the major alternatives?

VARLEY: Two Halon alternatives lead in market popularity. These are FM-200, a synthetic compound, and Intergen, a specific mixture of naturally occurring inert gases.

HANAUSKA: The market has definitely chosen HFC-227ea and the inert gas systems. These systems provide much of the clean agent system market, but other agents are strong in particular niches or geographic areas. However, development continues and new agents/product lines are being introduced.

ENGLER: Inert gas options, such as blends of argon, nitrogen and carbon dioxide, are also being used to replace Halon 1301, but they typically have higher initial installation costs.

For portable applications, FE-36—an HFC replacement—and Halotron I—a less costly HCFC replacement—are both used broadly to replace Halon 1211.

RIVERS: It’s true that hydrofluorocarbons, HFC-227ea and Inergen, became the products of choice for total flooding applications in the ’90s, but as for Mr. Hanauska’s point of continuing product development, no single alternative has been able to meet the same overall performance as Halon for both total flooding and streaming. To that point, in streaming applications, a hydrochlorofluorocarbon (HCFC) blend is now being used by three U.S. OEMs for hand-held portable extinguishers, while one uses HFC-236fa in portable extinguishers. The principal listing organizations—Underwriters Laboratories and NFPA—approve and recognize the new total flooding systems. UL also has tested the HCFC blend and HFC-236fa, validating their compliance with Federal Aviation Administration requirements. However, all HCFCs and HFCs have one common problem: They have an environmental profile that makes them non-sustainable. The industry has come to terms with the increased cost for these alternatives, but now, OEMs, end users and specifiers are becoming concerned they can no longer make the long-term commitment to the use of these non-sustainable solutions considering their overall impact on the environment.

CSE: This is an interesting argument. It’s obviously confusing trying to distinguish pros and cons. What advice would you offer a specifier?

VARLEY: The FM 200 system more closely resembles the Halon system, designed with a somewhat greater concentration, and accordingly, having agent tank piping and nozzle size somewhat larger. The Intergen system has a high concentration design with substantially larger tank storage and distribution system. FM 200 requires dedicated mechanical exhaust for its removal, while Intergen may safely be allowed to dissipate throughout an occupied building. Considering the ventilation requirement for FM 200, the initial costs of the two systems are comparable. The cost for recharging Intergen systems is less, and may be replaced by the supplier without cost.

RIVERS: To be sure, distinguishing among the various alternatives is confusing. The best way is to first consider safety for people, equipment and the hazard being protected, as well as safety for the environment. Second, consider whether the end user can commit to an alternative with confidence that there will be no repercussions down the road. Third, factor whether a halocarbon alternative is complimentary to inert gas alternatives—that is, when one agent isn’t practical, the other is. Last, but not least, factor the budget.

HANAUSKA: While it may be initially confusing, it is relatively easy to find good sources of information: NFPA’s “Standard For Clean Agent Fire Extinguishing Systems” (NFPA 2001) has important information about the agents, systems and their application; the EPA’s “Significant New Alternatives Policy” includes information about environmental acceptability; and finally, all the major clean-agent manufacturers and systems suppliers have a tremendous amount of information, including fire and discharge test data. The system agent and hardware should also be UL listed or FM approved. This, alone, will narrow the search considerably.

CSE: On the subject of confusion, what are the most common mistakes consulting engineers make when specifying clean-agent fire-suppression systems?

VARLEY: Under- or oversizing the system supply. Another critical aspect that is often overlooked is the evaluation of relative room tightness. In other words, is it sufficient to contain the agent, yet allow a sufficient release of the displaced air? For suppression systems in general, the mistake with the most severe consequence is the improper identification of the hazard category.

RIVERS: From our experience, we’ve found many designers use the minimum design criteria as determined by the listing or approval instead of what is actually specified for a particular fuel or hazard. Other mistakes include:

  • Using the wrong flooding factors.

  • Improper spacing of sprinklers, nozzles and detection devices.

  • Inappropriate detection methods for the particular hazard.

  • Incorrect sprinkler hydraulic calculations on wrong flow durations.

  • Incorrect foam quantities specified for the hazard.

  • Using incorrect construction classifications affecting the suppression system design.

  • Corrections not being made in clean agent quantity by not considering temperature, altitude, room volume.

  • Lack of safety devices and lock-offs for clean agents above the NO-AEL/LOAEL (no-observed-adverse-effect-level/lowest-observed-adverse-effect-level).

ENGLER: Coming from a bit of a different angle, I find the two most common mistakes are basing decisions solely on cost of the system installation and on meeting only minimum code requirements. In truth, the fire-suppression system will often represent well below 1% of the cost of the total facility. Yet that same system will be responsible for protecting business continuity—often valued at orders of magnitude higher than the cost of the facility. The fire codes only consider structural protection and do not focus on protecting a business’ assets, such as equipment, data and infrastructure.

HANAUSKA: I agree that these systems are often over and above the protection required by building or fire codes, so it’s extremely important to conduct a hazard evaluation of the application to ensure that the system being specified will truly meet the client’s fire-protection goals. This may at times necessitate going beyond the minimum requirements in NFPA 2001.

CSE: We briefly touched on this earlier, but what other new technologies are being developed or may come to light in the near future?

VARLEY: Development is proceeding on the part of some manufacturers on improved clean agents and clean-agent systems. Water-spray technology is progressing toward applications for larger and less specifically limited situations.

HANAUSKA: It appears that the choice of agents and systems is increasing with the introduction of some new products. The end user may be able to better match their needs with a fire-suppression system. One new product is 3M’s Novec 1230 fire protection fluid which has a very short atmospheric lifetime, and another is Kidde-Fenwal’s ADS FM-200 system which supports greater flexibility in the pipe networks.

RIVERS: Thanks. We feel Novec 1230 is superior to any existing Halon replacement because it meets the standards for gaseous fire extinguishing agents, it has a superior safety margin, it has a far superior environmental profile and it can be installed within budget.

ENGLER: There continues to be research on new Halon alternatives that more closely match the properties of Halon 1301, including efforts to find a “drop-in” alternative. In fact, HFC-227ea and our FE-25 products are being evaluated as retrofit candidates for Halon 1301 systems. The bottom line is that an end user should not wait for the “perfect” alternative. The focus should be on improving fire-protection capabilities to protect business continuity.


Reed Varley, P.E., Principal, Varley-Campbell & Assocs., Miami

Chris Hanauska, P.E., Senior Engineer, Hughes Assocs., Baltimore

Brian Engler, Global Business Manager Fire Extinguishants, DuPont Fluoroproducts, Wilmington, Del.

Paul Rivers, Product and Applications Development Specialist, 3M, St. Paul, Minn.

A Quick Look at Non-Clean-Agent Options

Clean agents are certainly one way to reduce property damage in the event of a fire, but other non-water protection options exist:

Carbon dioxide. This readily available alternative has the attributes of a clean agents, but has specific requirements set forth in NFPA 12. “It is useful for large volume or large surface hazard areas where effective personnel evacuation can be assured,” notes Reed Varley, P.E., principal of Varley-Campbell & Assocs., Miami.

High expansion foam. These systems contain a small percentage of water, but leave a residue.

Dry chemical. Useful for flammable liquids, these systems also leave an extensive powder residue, including one particular type that also leaves a sticky and difficult-to-remove residue.

Water mist. Currently limited to small and well-confined situations, according to Varley, these systems are not yet generally applicable to conditions where Halon alternative systems are typically used.

High-sensitivity smoke detection. “This type of detection system can alarm when a fire is very small, allowing manual intervention. It does require that trained and capable staff be present 24 hours a day to provide suppression,” says Chris Hanauska, a senior engineer with Hughes Assocs., Baltimore. He adds that pre-action sprinklers are another option that should prevent water damage from an accidental cause, but he notes they will not prevent water damage in the event of a fire. “This potentially makes the situation worse because the delayed application of water may allow for greater fire growth,” says the engineer.

Brian Engler, global business manager, fire extinguishants, Dupont Fluoroproducts, Wilmington, Del., however, notes that the problem with detection-only systems is that the end user is essentially gambling that they either will not have a fire event or that their employees will be able to react and extinguish the fire with portable extinguishers or some other means prior to incurring significant damage. “Use of detection-only systems has increased over the past few years. But DuPont believes it is because of a lost understanding among end users of the value of a clean-agent system,” says Engler. “With no direct experience of fire events, many choose the riskier option of no protection. But end users need to be aware that over $60 billion a year is spent on property damage and business interruption costs caused by fire events.”