Coal Age

MAR 2014

Coal Age Magazine - For nearly 100 years, Coal Age has been the magazine that readers can trust for guidance and insight on this important industry.

Issue link: https://coal.epubxp.com/i/277753

Contents of this Issue

Navigation

Page 48 of 59

nitrogen into the protected space. The emitter atomizes the water using low-pressure nitrogen, forming a dense homogeneous suspen- sion of mist that quickly fills the hazard space in a swirling pattern, enabling it to enter vented-type enclosures such as the cabinets typi- cal of an MCC room. The system does not require room integrity to be effective; fires can be extinguished in open, naturally ventilated areas. The Vortex system produces water droplets smaller than 10 microns in size, which is up to 100 times smaller than water particles delivered through traditional water mist systems. The small droplet size combined with the minimal amount of water released per emit- ter — 0.13 to 1.06 gallons per minute depending on emitter size — prevents significant wetting in the space, thereby avoiding damage to electrical equipment. Following discharge, residual moisture is barely detectable. In the Vortex system, the nitrogen and water mist function as complementary extinguishing agents. Nitrogen is the primary extin- guishing agent for smaller fires, reducing the oxygen level in the space to a breathable level where combustion cannot be sustained. In larger fires, the water mist is more effective, cooling the fire by absorbing the heat and reducing the available oxygen. The water droplet surface area is 90 times greater than that of standard sprin- kler systems, providing maximum heat absorption efficiency. By employing only non-toxic agents and maintaining oxygen at levels within safe breathing tolerances, the Vortex system does not pose any life safety hazards; evacuation and discharge delays are not required prior to system activation. In terms of water supply, potable water can be connected to the system via utility piping, or distilled/deionized water can be used via portable tank. The prep plant installed a 20-gallon tank of distilled water to minimize potential conductivity. Nitrogen is supplied in cylinders or tanks; the plant opted for the former. Based on volumet- ric calculations of the enclosures, 44 total cylinders were brought in: nine for each cable room, 13 for each MCC room. The number of emitters required is also based on hazard space volume. Each cable room required six emitters, each MCC room required eight. The con- trols, nitrogen cylinders, water tank and control panels were all installed in one of the MCC rooms. The prep plant's system is configured with individual detectors in each room, with zone control panels to isolate activation to the room affected by a fire. Each room is one zone, for a total of four zones. During the six-week installation period, plant operations were not affected. The system was commissioned in September 2013. Although MSHA doesn't require fire suppression systems for MCC rooms, insurance companies are increasingly recognizing the hazards and pushing plants to install them. In the past, such applications have presented obstacles, but hybrid systems offer promise in their ability to overcome the challenges associated with traditional fire suppression systems. In short, hybrid fire suppression technology provides a safe and effective solution for prep plant MCC rooms. Bob Ballard is senior project engineer, technical leader, with Victaulic, and Chris Yoder is fire suppression products manager with Pillar Innovations LLC. For more information about the Vortex sys- tem, visit www.victaulicvortex.com. o p e r a t i n g i d e a s c o n t i n u e d March 2014 www.coalage.com 47 Close-up of a single emitter during discharge. Animation depicting the swirling pattern of the nitrogen/water mist. CA_pg46-47_CA_pg46-47 3/12/14 2:58 PM Page 47

Articles in this issue

Links on this page

Archives of this issue

view archives of Coal Age - MAR 2014