Consulting-Specifying Engineer - May 2008 - (Page 18) Cover Story Schematic pre-action valve assembly • Not to scale Heat detectors or crossed zone smoke detectors Alarm bell Powered solenoid valve—closed To drain Air supervisory pressure switch To sprinkler system transmit the supervisory alarm signal, but keep the piping networks dry. Recently developed very fine fire spray or a water mist system provides another option for fire suppression systems. Requiring less water to suppress a fire than traditional sprinkler systems, the water mist method extinguishes a fire by absorbing its heat and by discharging very fine droplets (100 to 120 micron) of water. Water mist systems require unique hardware such as steel pipes, water container, pump, gas, nozzles, strainers, detection, and a panel. Water mist may provide a similar level of protection as a sprinkler system. Underwriters listed water mist systems for data centers using stainless steel pipes to mitigate micro biologically-influenced corrosion (MIC), which causes the development of pin leak holes in sprinkler piping. Gaseous suppression systems Gas-based fire suppression systems fight fires in three dimensions, in the space (Continued on page 22) To drain Pre-action system releasing panel Control valve with tamper switch To drain Tamper switch to building fire alarm panel Water flow pressure switch —alarm To drain To drain Water supply from the base building fire protection system Outside stem and yolk valve with tamper switch Note: Pre-action valve assembly installed in a cabinet is an optional configuration Figure 3: Electrically operated pre-action system using cross-zoned smoke detection or heat detectors for system release. Source: The Viking Group TM 3 LAYER PIPING SOLUTION PRODUCTS Input #209 at csemag.com/quickResponse 18 Consulting-Specifying Engineer • MAY 2008 http://www.flowguardflex.com http://www.flowguardflex.com http://csemag.com/quickResponse
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