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Protection of Data Processing Equipment With Fine Water Sprays. Annual Report. September 1993-September 1994.

pdf icon Protection of Data Processing Equipment With Fine Water Sprays. Annual Report. September 1993-September 1994. (2127 K)
Grosshandler, W. L.; Lowe, D. L.; Notarianni, K. A.; Rinkinen, W. J.

NISTIR 5514; 58 p. October 1994.


Federal Emergency Management Agency, Emmitsburg, MD

Available from:

National Technical Information Service
Order number: PB95-174975


water sprays; fire extinguishing agents; fire research; fire suppression; spray nozzles


The major objective of the work presented here has been to determine how a fine water spray compares to a gaseous agent in extinguishing fires in data processing equipment, an environment typically protected by halon 1301. A scaled-down, generic electronics package was designed and a chamber built to contain the water spray to emulate the physical system of interest. The mock electronics cabinet is 0.5 m wide, 0.2 m deep and 0.4 m high. The fuel is a 3 mm thick plate of poly(methyl methacrylate), placed vertically in an aluminum frame centered among a number of aluminum "circuit boards." The limitations imposed by the different transport phenomena associated with droplet versus gas dispersion have been investigated. The influence on extinguishing efficiency of the nozzle geometry, the location relative to the fire, the water application rate, and the amount of shielding surrounding the fire within the simulated cabinet are all parameters which have been examined. A gaseous agent, CF3H, is used for comparison. A phase-Doppler particle analyzer measured the droplet size distribution and velocity. The water pressure has a significant effect on the size of the region in which a fire can be effectively suppressed. The reasons for this are the greater flux of water and the increased momentum of the spray resulting from higher water pressures. With the full enclosure in place around the fuel source, extinguishment is possible only at the highest pressure (5.5 MPa), with the objection the spray centerline, and with at least 40% of the top area of the cabinet directly open to the spray. By contrast, similar fires in all geometric configurations can be successfully extinguished with CF3H as long as the concentrations in the chamber are close to those recommended in NFPA 2001.