DATA CENTERS AFTER HALON

For many years, Halon 1301 was the holy grail of fire suppressants for highvalue assets that would be damaged by traditional sprinkler systems. But, in 1989, when the Montreal Protocol determined that halon depleted the ozone layer, and the U.S. Environmental Protection Agency subsequently banned its manufacture in 1994, the search was on for halon replacement options.

It's true that properly maintained systems could be grandfathered and remain in use. Some are still in use today, but, like any mechanical system that is 15 years old, current halon systems are getting a bit long in the tooth. Parts are harder to come by, and there are fewer people capable of servicing the older units.

Halon 1301 succeeded so well because it could be used in data centers, IT rooms, museums, libraries, surgical suites, and other locations where use of water-based suppressants could irreparably damage electronics or vital archival collections.

Since halon manufacturing was banned, a hunt has been on for something that works as well. According to the Halon Alternatives Research Corp., more than 20 different kinds of alternatives exist as direct replacements.

Omitting traditional, water-based sprinkler systems for the moment, two basic categories of halon-replacement systems exist, according to Chris JeIenewicz, engineering program manager for the Society of Fire Protection Engineers. Those categories are inert gases and halocarbon compounds. Which one is better? That depends on the needs of a given organization.

Inert Gas 

The principle behind inert gas systems is reasonably simple: Once sensors determine that a fire (or threat of fire) exists, atmospheric gases are released into the space to lower the amount of oxygen. Essentially, the introduction of higher concentrations of other atmospheric gases suffocates the fire.

The key for manufacturers of inert gas systems is to achieve the right balance of gases. It's a tricky matter.

Oxygen levels above 15 percent allow combustion to continue, according to Joe Behnke, manager, technical services for engineered systems in Tyco's fire suppression and building products division. "Below 10 percent oxygen, and the concentration does not support human life," he says.

The balance of other percentages of gases is vitally important, too. That's because carbon dioxide in concentrations above 10 percent is toxic to humans.

Generally, manufacturers of inert gas fire suppression systems combine argon, nitrogen and carbon dioxide - all naturally occurring gases in the Earth's atmosphere - to achieve fire suppression.

Clean Agents

After halon was banned, other "clean agent" systems were developed diat have no known ozone-depleting capacity.

From a chemist's perspective, two main types of clean agent systems have replaced Halon 1301. Both are halocarbons:

1. Fluorinated ketones: The structure of these chemicals contains carbon, fluorine and oxygen.

2. HFCs: Hydrofluorocompounds (HFCs) contain no chlorine or bromine - the two ozone-depleting elements identified by the Montreal Protocol. The chemical structure of these agents contains carbon, hydrogen and fluorine. These were the very first halocarbon agents developed after the Halon 1301 ban.

Each clean agent is stored as a liquid at room temperature but becomes gasified by the delivery nozzles, according to Brad Stilwell, manager of new product development for Fike Corp.

As a gas, they displace air and work "by taking the heat out of the fire," says Joe Ziemba, a marketing manager for 3M's Novec product.

To a layperson, that means that the molecular structure of halocarbons chemically reacts with other molecules whenever a fire is present, chemically destroying the propagation of flames.

Making the Choice

Inert gases will never be banned by findings from climate change agreements or government organizations because the gases they use occur naturally in the atmosphere. They do not harm the environment and are not toxic to human beings. They take slightly longer - up to 60 seconds to suffocate a fire - than halocarbon compounds. Because they are stored in gaseous form, they also require significantly more canisters than the halocarbon compounds.

But inert gas canisters can be located much further away from a protected enclosure than canisters of halocarbon clean agents. Most experts say that inert gases can be run in piping up to 400 feet, whereas clean agents require positioning of canisters inside, immediately outside, or directly above a protected enclosure because of their lower viscosity and lessened ability to flow inside suppression system piping.

Whether using gases or liquefied compounds, both systems are "total flooding" suppressants - meaning that to work effectively, they have to flood the enclosure. This requires what Behnke calls "enclosure integrity."

"Once the system is discharged, there's minimal cleanup," he says. "But they require a 10-minute 'hold time' to ensure that the fire is extinguished."

Protected enclosures that use clean agent systems should conduct door-fan tests to determine enclosure integrity, says Stilwell. These tests can be conducted using National Fire Protection Association (NFPA) Standard 2001, which can also be used for smoke and refuge tests for other areas of a building.

Because of the higher pressures required for inert gases, enclosures that use these systems should be appropriately vented to release pressure while ensuring that oxygen is effectively displaced.

The Alternatives

According to Jelenewicz, water mist technology is also being used as an alternative to halon.

"Water mist systems use a very fine water spray to extinguish a fire and generally require less water than a standard sprinkler system to adequately control a fire," he says.

As a result, water mist systems use smaller diameter piping and do not weigh as much as a standard sprinkler system. Because of these qualities, water mist systems have been used to protect a diverse array of hazards that include passenger ships, machinery spaces, museums and locations with limited water supplies.

Facility executives who might not need to protect a vital data center or who might have a higher threshold for risk are also considering pre-action sprinkler systems as an alternative to halon. These systems use a dual-sensor system designed to prevent water from moving into the piping above a protected area unless a fire is detected - thereby mitigating the potential for damage caused by leaks or false alarms.

Facility Considerations

NFPA Standard 2001 addresses clean agent use, including the design, installation and maintenance requirements for systems that employ replacement agents.

If the existing Halon 1301 hardware is in good condition, says Jelenewicz, facility executives might want to consider a replacement that can be used with the existing hardware.

"For example, most of the halocarbon compounds can be used with existing hardware," he says.

Other sources, including Ziemba, say that any replacement for a halon system will require more cylinders, and therefore requires at least some additional piping.

"I'd recommend replacing the piping if you have the space and availability," he says.

When in doubt, consult with a fire protection engineer. "Fire protection engineers understand the science and the latest technologies that are used to protect people, property and the environment from fire," says Jelenewicz.

Additionally, a fire protection engineer can assist in determining the appropriate fire-extinguishing agent given the specifics of an organization's application. They can also assist in preparing the design, installation and maintenance requirements.

Other Considerations

Aside from finding the appropriate facility space for the suppressant system and ensuring enclosure integrity, two other considerations might sway the facility executives' decisions: cost and environmental considerations.

"You know, a lot of facility directors are looking for the least expensive item," Behnke says. "Unfortunately, there's no such thing as a cheap fire."

Any halon replacement system is more expensive than a traditional sprinkler system; therefore, facility executives typically use halon replacement suppressant systems in high-asset locations, where the use of water could be catastrophic to data, valuable physical items that are literally irreplaceable (the state library of Pennsylvania uses a halocarbon system to protect a collection of writings from Ben Franklin), or revenue stream. Keep in mind that refills on inert gas systems that have discharged are generally less expensive than refills for halocarbon compounds.

Inert gas systems have no potential for ozone depletion. Although they contain carbon dioxide, which contributes to global warming, they are not considered a target for phase out for global warming concerns.

The atmospheric life for.both Novec 1230 and HFCs is comparatively short - about five days for Novec - and neither causes ozone depletion. But clean agents do have global warming potential. Manufacturers of clean agents say that it is unlikely but nevertheless possible their products could be phased out under climate change agreements or legislation, and so they provide substantial warranties for the products. The exact terms of the warranties differ. One manufacturer offers a 20-year warranty on HFCs, guaranteeing that it will replace the system if HFCs are banned. Another manufacturer offers a lifetime warranty on the product, promising to buy it back from the purchaser if the product is ever banned.

As always, after any replacement system has been installed and commissioned, the facility staff should receive proper training on its operation and implement a maintenance and testing plan for the new system. This maintenance plan should include the hardware that is part of the suppression system, as well as addressing the detection and notification systems and the enclosure integrity.

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