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HALON REPLACEMENT PROGRAMS AT THE NAVAL RESEARCH LABORATORY

 WASHINGTON, Feb. 17 /PRNewswire/ -- The Navy's current use of halogenated fire-fighting agents consists primarily of Halon 1301 systems. Approximately 2,000 Halon 1301 total flooding systems are installed on 300 Navy vessels. Halon 1301 is an extremely efficient suppressant for quickly extinguishing hydrocarbon fuel fires, while causing minimal damage to naval systems. The Navy also uses Halon 1211 for flightline fire protection. However, environmental concerns about stratospheric ozone layer depletion have mandated finding replacements for Halons. Most importantly, worldwide production of Halons will halt by January 1994, as dictated by the international Montreal Protocol Treaty and its modifications.
 Preliminary calculations at NRL in the mid-'70s showed that Halons, with component bromine, would likely be more potent on a molecular basis than chlorofluorocarbons (CFCs) in causing ozone depletion. Accordingly, a project was initiated at NRL to find replacement agents.
 The Navy Technology Center for Safety and Survivability (NTCSS) at NRL has long had expertise in flammability limit phenomena, spontaneous fir ignition and flame suppression. In 1988, with growing ozone depletion concerns, NTCSS's research on Halon fire suppression and replacement agents for Halon was intensified.
 Halon 1301 Discharge-Test Replacement
 New and retrofit shipboard installations required full acceptance discharge tests of Halon 1301; however, discharge tests accounted for more than 60 percent of the Navy's total release of Halon 1301.
 NRL has demonstrated that sulfur hexafluoride (SF6), a non-toxic, environmentally friendly gas, could be used as a stimulant for Halon 1301 for discharge testing.
 As a result of the successful tests on the USS Chancellorsville (CG-61), the Naval Sea Systems Command has directed that all future discharge tests be conducted with SF6, instead of Halon 1301. Since then, SF6 discharge tests have been conducted on 13 other ships. To date, by the use of SF6, the Navy has prevented the release of 36 tons of Halon 1301 into the atmosphere, thereby making a substantial contribution to an improved environment.
 Water-Mist Fire Suppression
 Water is an inherently effective fire-fighting agent. However, only recently have the dilution and cooling effectiveness of water mists been included in the search for a replacement for Halons in vital shipboard spaces. Experimental work has been performed in the past at NRL to demonstrate the use of water mist in vented compartments and pressurized chambers. The current NRL research program is involved with intermediate and full-scale experiments at NRL and on NRL's fire research ship, the ex-USS Shadwell. These experiments are designed to take a look at recent advances in water- mist technology, with emphasis on hardware and system design. With proper understanding and design of a water-mist system, an advanced, highly effective and environmentally safe fire-suppression system would be developed for the fleet.
 Nitrogen Replacement for Halons in Closed Spaces
 Nitrogen is an ideal choice as a replacement extinguishment agent for Halon gases since nitrogen is non-polluting, presents no health hazard and will not impair the function of ship systems. The goal of the NRL nitrogen fire-suppression program is to provide the science base required to develop solid-state sources for the production of nitrogen for total-flooding fire-fighting systems. A condensed-phase source, which consists of sodium azide and a metal oxide, is a likely research approach. This approach would produce the needed nitrogen suppression, while creating acceptable by-products, similar to those found in air bags in cars, but generating nitrogen at lower temperatures.
 Halon 1211 Replacement for Training
 The Navy uses Halon 1211 for flightline fire protection. A non- ozone depleting simulant is needed for training for crash and rescue personnel on various types of fires, such as engine, nacelle, crash, and cascading fuel fires, etc.
 NRL is currently developing portable fire extinguishers using non-ozone-depleting simulants with the same discharge characteristics as Halon 1211 for training purposes.
 Combustion Suppression Mechanisms
 To develop acceptable replacements for Halons, it is necessary to understand the mechanisms by which they suppress fires.
 A substantial research effort is underway at NRL on the measurement of the effectiveness of suppressants, the development of the chemical and physical mechanisms by which they suppress fires, and the development of theory and models on the relationship of chemical structures to suppressive behavior.
 -0- 2/17/93
 /CONTACT: Dick Baturin, public affairs branch, Naval Research Laboratory, 202-767-2541 or, fax, 202-767-6991/


CO: Naval Research Laboratory ST: District of Columbia IN: ARO CHM SU:

TW -- DC001 -- 7465 02/17/93 15:43 EST
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