Protection of Data Processing Equipment With Fine Water Sprays. Annual Report. September 1993-September 1994.
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.
Sponsor:
Federal Emergency Management Agency, Emmitsburg, MD
Available from:
National Technical Information Service
Order number: PB95-174975
Keywords:
water sprays; fire extinguishing agents; fire research;
fire suppression; spray nozzles
Abstract:
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.
