| Popis: |
The capacity of existing overhead foam dispensing sprinklers to extinguish fires shielded by aircraft and/or vehicles was measured under the crowded conditions encountered on hangar decks and in ships holds. Simplified shadowing geometries were used in a series of 10 foot diameter. JP5 fires extinguished with AFFF at application rates ranging from .16 to .22 GPM/sq ft. Findings from these model fires were confirmed in a series of 40 foot by 40 foot fires under full sized trucks and aircraft wings. Until the flames are knocked down, a substantial fraction of the agent is lost in the fire plume; however, the extinguishment time is controlled primarily by the rate of foam migration under the aircraft and vehicles. The existing sprinklers extinguished the burning JP5 and would provide protection for the ship but aircraft in the flames will suffer serious damage before the fire can be extinguished from overhead. The migrating foam does not cover or extinguish shielded combustibles that extend above the liquid fuel; consequently, the many tires on the stowed vehicles continued to burn and, unless extinguished by hand lines or other means, soon reignited the JP5. In order to prevent damage to aircraft and vehicle, additional applicators are required to apply agent directly to the seat of the fire. |
