Consulting-Specifying Engineer - May 2008 - (Page 22) Cover Story (Continued from page 18) itself and under the equipment cabinets. Designed to protect the equipment and data in process, gas-based systems do not leave a residue or require any clean up of the equipment after it discharges. Clean agent extinguishing systems suppress fire in the incipient stage. Similar to the pre-action system, clean agent extinguishing pipes contain no gas. Gas will discharge upon activation of the cross-zoned detection system and subsequent mechanical and electrical systems shut down, flooding the room in 10 sec (with the exception of inert gases, which are required to discharge in 60 sec). Although it takes under two minutes to suppress the flames, done by absorbing the fire’s heat, gas in the room is specified to maintain concentration for as long as Commissioning fire detection and suppression systems Commissioning a data center’s life safety system can be just as crucial as its initial design. Documenting and validating the system’s viability throughout the project assures both the specifying engineer and the owner that building operations match projected performance criteria. The following is a short list of life safety systems that need to be commissioned and their appropriate testing criteria: 1. Underground fire mains shall be tested in accordance with NFPA-24 by flushing before backfilling, performing a hydrostatic test, inspecting the location of thrust blocks, and completing contractor material and test certificate. 2. Sprinkler system commissioning includes a pneumatic test of the dry and pre-action systems, the valve supervisory devices, and a hydrostatic test of the wet, dry, and preaction systems; a trip test of the dry system and detection devices; a loss of air test and a solenoid release of the pre-action system. 3. The clean agent extinguishing system shall be evaluated in accordance with NFPA 2001 by testing smoke detectors at the ceiling and under the raised floor by activating manual pull stations and abort switches, sampling the power shut to the equipment and by performing a flow (puff) test to make sure that pipes and nozzles are free of obstructions, a pneumatic test of piping and by verifying trouble and alarm status at the building fire alarm panel. 4. The fire alarm system shall be tested in accordance with NFPA 72 by verifying the monitoring of fire suppression trouble and alarm zones, testing alarm initiating devices, activation of duct smoke detectors, air handling shut down, activation of notification appliances verifying the sound levels of audible devices, elevator recall and the tie in of fire alarm panels to the UL-listed central station; verifying the sound levels of audible devices. 5. The VEWSD shall be tested for the travel time of its smoke alarm (maximum of 120 sec), verifying alert, action fire 1 and fire 2 status as well as trouble and alarm status at the building fire alarm panel and verifying flow pressure of sampling holes. Additional references: • International Code Council: www.iccsafe.org • Society of Fire Protection Engineers: www.sfpe.org • Fire Protection Handbook: www.NFPA.org 10 min to obliterate smaller fires in any hard-to-reach places. In order for gaseous systems to be effective, though, the space has to be air-tight, with all door, floor, and ceiling openings sealed. The gases used, including FM-200 (HFC 227), FE-25 (HFC-125), 1230 Novec, and inert gasses including inergen (IG-541) and argon, are odorless, non-toxic, non-corrosive, electronically non-conductive, and environmentally-friendly. (Note: Venting of the space is required when high-pressure inert gasses are used.) Once a gas discharge has taken place, however, its storage tanks need to be refilled. Very often, depending on the location of the data center and its proximity to a vendor, it can take as long as 24 to 48 hours to replace the gas agent needed to suppress another fire. For this reason, some mission critical facilities are now reserving back-up tanks, maintaining twice as much gas storage at all times. Integrated systems Most local jurisdictions require water-based fire extinguishing systems, while gaseous systems often provide the preferred protection for computer room equipment. In order to satisfy each requirement, a typical data center will be outfitted with both. Here’s how it works: if the fire isn’t suppressed by the gas system, the sprinkler system will subsequently activate, but is otherwise maintained as the official back-up extinguisher. Specifying the appropriate fire detection and suppression systems for each data center will increase its survivability. Most fires in mission critical facilities can be prevented if fire detection and suppression systems are properly designed, installed and commissioned in accordance with applicable standards. Salwan is a registered PE in both Illinois and California as well as a technical committee member for NFPA Standards 14, 24, 72, 75, 291 and a member of the Society of Fire Protection Engineers. As a senior associate at ESD, Salwan supervises the design and implementation of fire suppression and life safety systems in a variety of mission critical, residential, healthcare, education, commercial, and industrial projects. 22 Consulting-Specifying Engineer • MAY 2008 http://www.iccsafe.org http://www.sfpe.org http://www.NFPA.org
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