Testing CAFS in Live Burns

Testing CAFS in Live Burns

SPEKE AIRPORT, ENGLAND

A series of practical comparative tests were performed at Speke Airport in Liverpool, England, on January 19 and 21, 1994. Its objective was to ascertain if compressed-air foam system (CAFS) foam application had an advantage over conventional foam application in extinguishing pressurized aviation fuel fires. An onsite training aircraft rescue-firefighting fuselage mock-up was utilized to simulate three separate pressurized fuel fire scenarios using a 50/50 mix of JP-4 jet fuel and #2 fuel oil. Multiple fire attacks, using a 2’/Hnch CAFS handline flowing between 80 and 180 gpm of one-percent AFFF foam solution, were made to quantify the minimum application rate required (and the most aggressive nozzle-handling technique) to extinguish each of the three fire scenarios.

The CAFS gpm application rate threshold for extinguishment was reached for each scenario. Then the same gpm foam solution flow (minus the compressed air) was aggressively applied to the next fire through an adjustable gallonage/constant flow nozzle. In each of the three fuel fire scenarios, the foam solution flow applied by conventional nozzle did not extinguish the fire, regardless of how long it was applied. While strictly preliminary, these tests demonstrated that, under those conditions, when foam solution flow is discharged as CAFS foam, it has more firekilling power than when applied with a conventional nozzle.

The Speke Airport ARFF simulator's pressurized fuel screen. The screen flows 34 gpm of atomized fuel in a counterclockwise impinging nozzle pattern. The CAFS attack is flowing 180 gpm of foam solution (one-percent AFFF) and 90 scfm of compressed air (1 gpm:0.5 scfm ratio), with a 1 5/8-inch ball valve nozzle. Extinguishment time was 30 seconds. Fire attack on this same fire with 180-gpm foam solution (one-percent AFFF) through a variable-gallonage/constant flow nozzle did not extinguish the fire.Simulated wing engine fire flows 25 gpm of atomized fuel from internal and external spray nozzles. A CAFS application rate of 135 gpm foam solution (onepercent AFFF) and 70 scfm of compressed air extinguished this fire in 40 seconds. Fire attack with the same 135 gpm of foam solution through a variable gallonage/constant flow nozzle did not extinguish the fire.

LIMERICK, PENNSYLVANIA

Live tire training in Limerick, Pennsylvania, included CAFS used in direct fire attack. This bum building, a 25by 30-foot wood frame building with a heavy fuel load, was given a 14-minute prebum. It then was attacked with a 2’/2-inch handline with a two-inch smooth-bore tip, flowing 120 gpm/120 scfm with Class A foam concentrate at 0.3 percent. The fire^ was knocked down by firefighters in 25 seconds.

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