Mechanical Engineering Department
BS in Mechanical Engineering
Chris Pascual, Fred Mowrer
Compressed air foam fire suppression systems (CAFS) were tested to measure the potential safety risks involved with its use compared to water. CAFS are mainly used in wildland firefighting, but could be more effective than water at extinguishing fires in interior settings. The purpose of these tests was to conclude if CAFS are safe for use in structural firefighting when compared to water. The tests conducted included measuring the nozzle reaction force, force required to kink a hose, force of friction on different walking surfaces, and the time required for foam and water to separate within a pressurized segment of hose. Nozzle reaction force was measured at flow rates between 80 and 200 GPM for compressed air foam and water. At each flow rate, CAFS had a greater transient and steady reaction force than those measured for water. The force required to kink hoses filled with CAFS was significantly higher than hoses filled with water while flowing and static. On five different interior floor surfaces, the force of friction required to pull a 200 pound weighted fire boot decreased when wet with water and when covered with CAFS. The tendency for the foam structure to break down and separate within a hose was tested using a 32 foot clear PVC pipe apparatus. After being filled with compressed air foam and timing the separation of solution from water, results concluded that separation of foam occurs over a long period of time that does not pose a threat in a real life situation. The average time for homogeneous flow to re-establish after the allowed separation was 3.6 seconds.