Abstract

The objective of this test series was to identify changes in extinguishing performance of combinations of Fluorine-Free Foam (F3) concentrates and/or Aqueous Film-Forming Foam (AFFF) concentrates when mixed together. Four types of tests were chosen to examine the effects of mixing in different use cases: Mixed Immediate Use, Mixed Short-Term Stability, Mixed Medium-Term Stability, and Dual Application.

The performance of mixtures between foam concentrates did not always have predictable results. The performance of mixtures between AFFF and F3s tended to be close to the performance of AFFF alone or between the performance of the individual foams. F3 mixtures were more varied, with most showing performance better than the individual foams, one showing performance between the performance of the component foams, and one showing a severe reduction in performance. Given the amount of variation in foams both in performance and chemical makeup in the F3 market, it is important to not mix concentrates without more testing to ensure compatibility.

The Dual Application tests showed much more predictable performance than the mixed-concentrate tests. Extinguishment and burnback times were close to or between the baseline values of the component foams in all tests. Based on this result, use of two different foams (e.g., dispensed from two different Aircraft Rescue and Fire Fighting [ARFF] response vehicles) in the response to a fire may not have any significant impact on firefighting performance.