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General Information
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October 23, 2009
• Vol.31 Issue 26
Page(s) 26 in print issue
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Prevention, Detection & Suppression
The Key Components Of Data Center Fire Protection Systems
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| Key Points
• Part of a comprehensive fire protection plan is prevention, which includes testing existing fire detection and suppression systems and procedures.
• Fire detection sensors are vital to picking up early signs of trouble, potentially saving thousands of dollars in damage and downtime.
• Fire suppression systems are generally water-based, clean agent-based, or a combination of the two. | | The U.S. National Archives and Records Administration says that as many as 93% of companies that experience the loss of their data centers for 10 days or more due to a disaster file for bankruptcy within one year of the disaster. Fires—even minor ones—fall into the disaster category.
Michael Young, CTO of Redfin (www.redfin.com), has experienced outages due to data center fires not once, but twice. Loaded with transformers, power supplies, motors for HVAC systems, and telecommunications equipment, it's easy to see how quickly a malfunction or overload could lead to a fire within the data center. Fortunately, Young’s downtime only spanned several hours the first time and several minutes the next, thanks to a robust disaster recovery and redundancy plan instituted after the first fire.
 Regardless if your data center is serving a small to medium-sized business or a multinational enterprise, a fire protection system is imperative to business continuity.
Similar to data center security, fire protection is best with a multifaceted approach that includes prevention, detection, and suppression, each employing a variety of methods and technologies.
 Prevention
Regardless of what type of fire detection and suppression system data centers choose to install, the most critical step of all is to have a concrete, written plan in place. According to the National Fire Protection Association (www.nfpa.org), fire protection systems need to be regularly and thoroughly tested.
This includes testing the physical aspects of the entire system such as sensors, batteries, and discharge mechanisms and ensuring an adequately charged system. Similarly, fire prevention tests should include fire drills covering disaster recovery plans, personnel notification, and evacuation of the facilities.
“We would have never been back online in such a short period of time if we hadn’t planned accordingly after experiencing the first fire,” says Young.
Detection
Veteran data center administrator and consultant David O. Jackson points to a variety of factors that make fire detection within data centers challenging. “Data centers have unique airflows and spaces, such as raised floors, hot and cold aisles, and enclosed racks.”
In order to achieve adequate protection, Jackson relies on sensors for smoke, heat, and flame within key areas of his data centers. “Today’s environmental monitoring systems, especially the IP-based systems, can provide early warnings, especially at the rack level,” he says. “When a power supply overheats, it doesn’t matter where I or my staff is, we can be immediately notified and prevent further damage.”
Fire can start just about anywhere throughout the data center, so Jackson covers his bases with two different types of smoke detectors.
EWSDs (early warning smoke detectors) and VEWSDs (very early warning smoke detectors) are sensitive enough to detect the first molecules of smoke and even smoldering materials. There are two types of EWSDs—ionization and photoelectric. Both are commonly placed in airflow areas such as supply and return ducts. Advanced systems integrated into an HVAC system can deter smoke from moving throughout the physical environment through a series of automated dampers and fans within the duct system.
While the EWSD works in a passive mode, the VEWSD works in an active mode by constantly sampling air for particles of both visible and invisible smoke. Highly sensitive detectors analyze air samples aspirated from key areas. This type of early detection system is often found in data centers handling mission-critical operations.
Flame detection systems are reserved for areas where fires can flash within seconds, such as compressors, transformers, and high-voltage equipment. “Anything that can throw sparks has a flame detection sensor in the vicinity,” says Jackson.
Suppression
Once detection is confirmed, the next step is to extinguish the fire using either water, clean (gas-based) agents, or a combination.
“Wet servers are not something I want to have in my data center, but for protecting the overall physical facilities, it’s the least expensive option,” says Jackson, who uses a combination of extinguishing agents when designing new and retrofitting older facilities.
In addition to being more cost-effective, water-based fire suppression systems have been utilized much longer than gas-based agents, meaning facilities, fire, and inspection personnel are much more familiar with their maintenance and operation.
There are two main types of wet suppression systems: wet pipe and dry pipe. Water is present at all times in a wet pipe system, whereas a dry pipe system is activated automatically by a detection system or manually.
Clean agents are gas-based systems that flood the area and extinguish fires through the elimination of oxygen. Many clean agents are able to permeate racks and equipment and leave no trace once deployed. Compared to a water-based suppression system, they are significantly more expensive.
Lance Harry, commercial director of Marioff’s North American division (www.marioff.com), lists a number of clean agent brands, such as Argonite, FM-200, and Novec 1230, commonly found in data centers. Many of these have been developed to replace Halon, one of the first gas-based agents widely deployed for fire suppression in clean environments starting in the 1970s. In 1987, the use of Halon was banned due to its ozone-depleting properties.
Although existing Halon systems are grandfathered in, Harry warns that in the event of a discharge, the system might not be able to be recharged with Halon. Some Halon-based systems are capable of switching over to other agents, such as FM-200, but it’s worth the time to understand the implications of maintaining a Halon-based suppression system. “I’d highly suggest anyone still using a Halon-based system start making plans to replace the agent or even the entire system with something more fiscally predictable and environmentally acceptable,” advises Harry. 
by Sandra Kay Miller
Heading
• Early warning smoke detectors: Passive smoke detectors that utilize ionization and photoelectric sensors. Often placed in high-airflow areas such as ducts, ceilings, and raised floors.
• Very early warning smoke detectors: Actively sample air particles for smoke through regular sampling of air via aspiration. Can detect nonvisible smoke.
• Wet pipe: A water-based fire suppression system that constantly maintains liquid in the piping.
• Dry pipe: A water-based fire suppression system that does not fill the delivery pipes until a detection system or manual lever engages the system.
• Clean agent: The medium used in a gas-based fire suppression system that leaves no trace or damage to equipment. |
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