Fighting fire with oxygen deprivation

As data centers become hotter and more dense with servers, a greater chance for fire exists. But there's equipment on the market that applies a well-known method of halting fire: starving it of oxygen.

Only a few vendors are offering oxygen-deprivation systems, but interest in the technology is growing. It involves pumping air that has such a low oxygen content that a fire can't start in the data center.

Air is composed of about 21 percent oxygen, 78 percent nitrogen and 1 percent of other gases. Fire needs the oxygen to burn, and lower percentages of oxygen makes it more difficult or impossible for fire to start.

Wood stops burning when the oxygen content falls to 17 percent and plastic cables between 16 to 17 percent, said Frank Eickhorn, product manager for fire detection at Wagner Alarm and Security Systems GmbH in Hanover, Germany.

Wagner makes electric compressors that use a special membrane to remove some of the oxygen from the outside air, a system the company calls OxyReduct. The excess oxygen is exhausted, and the remaining nitrogen-rich air is pumped inside the data center.

At 15 percent oxygen, it's safe for humans to enter. The lower oxygen content of the air is similar to being at an altitude of about 6,000 feet, Eickhorn said. He demonstrated with a lighter inside a sealed atrium Wagner has on display at Cebit. It won't light.

Fire poses a danger beyond the immediate equipment that burns. Burning plastic components combine with moisture in the air to create an acidic vapor that can damage other equipment away from the flames, said Dieter Lietz, manager for technical training and support. Smoke damage is just as costly for insurance companies as fire, Lietz said.

N2telligence GmbH, a startup company based in Hamburg, Germany, has taken the oxygen-deprivation concept a step further by using a fuel cell. The fuel cell provides two functions: it can supply low-oxygen air to the data center and power during a sudden outage, said Lars Frahm, one of N2telligence's co-founders.

N2telligence showed a fuel cell at Cebit that uses two, 50-liter tanks of hydrogen for fuel. It's made by Plug Power Inc., a U.S. company in Latham, New York. The air that's discharged from the fuel cell reaction has less oxygen, and a condenser removes a bit of water vapor before the air is pumped inside the data center, Frahm said.

"It (the air) is even worth more than the electricity that comes out of it," Frahm said.

But that electricity can also be in case of a power failure. N2telligence's fuel cell is equipped with a battery to immediately supply power to the data center while the fuel cell reaction starts, usually within a few seconds, Frahm said. Overall, fuel cell technology is best for small data centers, Frahm said.

Both N2telligence and Wagner were reluctant to quote a cost for their systems, as it depends on the air-tightness of a data center and its size, among other factors, they said. Wagner has sold about 200 systems over the last couple years as demand has grown, said Peter Clauss, Wagner sales director.

N2telligence was formed in July 2006 and just put up its Web site last week, Frahm said. The three-person company is self-funded, although a partnership is expected soon with Kidde, the fire safety division of United Technologies Corp., he said.

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Copyright © 2007 IDG Communications, Inc.