Test Conclusions
The following conclusions were derived from the tests:
The CFR for plain water is between 70 and 80 gpm, say 75 gpm. For aspirated foam, the CFR is between 40 and 60 gpm, say 50 gpm. The CFR for a straight stream of plain water, therefore, is about 50 percent greater than for aspirated foam–that is, 50 percent more water is needed to darken the fire with plain water than with aspirated foam.
Visibility was improved with foam.
The fire rekindled more reluctantly after application of foam than after the application of plain water.
The comparison between plain water and aspirated foam is expected to be reproducible and, therefore, is considered to be conclusive.
The distinction between fire knockdown (defined as “no flame visible above the crib top as seen by the camera above the nozzle”) and no knockdown appeared to be quite sharp, Edwards points out. He adds that results were monotonic with flow rate and consistent and that no attempt was made to optimize the pattern, expansion ratio, drain time, and method of application. Optimization, he estimates, is likely to reduce the CFR by a factor of two.
The test results, Edwards continues, suggest that the CFR can be determined to within ± five percent, so that the method can be used to compare concentrate formulations, nozzles, methods of application, and mix ratios for different fuels, probably with three fire tests for each variation.
Tests were restricted to seven in 1995 because of adverse weather factors. If normal weather conditions prevail and additional funding becomes available, the remaining 53 cribs are expected to be burn-tested by the end of 1996. The resulting data should provide a credible and accurate comparison of foam solution, aspirated foam, CAFS, and plain water applied with several patterns and methods of application, according to Edwards.
A detailed report and video will be prepared after test data analysis has been completed. For more information, call or fax Edwards at (604) 547-6470.
