Consulting-Specifying Engineer - May 2008 - (Page 16) Cover Story SUPPRESSION BY SAM SALWAN, PE, Senior Associate, Environmental Systems Design Inc., Chicago Data center fire Flames and smoke can irreversibly damage a facility and its data processing systems. Designing critical facilities for survivability is key. Minimize the risk of fire damage by maximizing detection and suppression with the right systems. T he average 14,000-sq.-ft data center pushes a 2,400 kW load and 700 tons of heat daily. Generated by small blade servers and overcrowded racks, loads of this size burden the data center’s electrical circuits—which may not be properly grounded—causing equipment to overheat in areas without proper cooling. A simple equation applies: Large loads + combustible scenarios = the greatest threat to the data center’s 24/7/365 existence: a computer room fire. Flames and their smoke cause irreversible damage to a facility and its data processing equipment, often forcing the facility to close its doors. According to the U.S. National Archives and Records Administration, College Park, Md., as many as 93% of companies that lose their data centers for 10 days or more due to a disaster file for bankruptcy within one year. Designing today’s critical facilities for their survivability is key. Minimizing the risk of fire by maximizing detection and suppression with the right systems will mitigate the threat that large loads and combustible scenarios pose to any data center’s uptime. Fire detection systems The unique airflow patterns within a data center create a challenge for smoke and fire detection systems. Unlike a typical commercial building, the data center is outfitted with hot and cold aisles and underfloor and overhead spaces, each separated to contain airflow within the space. For this reason, conventional detection methods don’t meet the data center’s needs. Instead, additional fire detection strategies need to be considered concurrently to achieve reliable protection. The architectural and mechanical layout of each data center will determine whether the facility needs an Early Warning Smoke Detector (EWSD) or a Very Early Warning Smoke Detector (VEWSD). The EWSD system provides detection typically at the first sign of smoke, while a VEWSD will expose an incipient fire smoldering for hours or days before a flame ignites. Automatic spot-type detectors are the most common form of EWSDs, available in ionization and photoelectric types. Using ceiling sensors, these passive detectors rely heavily on high airflow for their optimal performance. Duct detectors are 16 Consulting-Specifying Engineer • MAY 2008
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