Study of the stability of alcohol-resistant aqueous film forming foam on class B fuels with different polarity and boiling point

To investigate the impact of liquid fuel characteristics on the stability of Alcohol-Resistant Aqueous Film Forming Foams (AFFF/AR), representative Class B fire fuels with distinct boiling points and polarities - ethyl alcohol, propanol, n-hexane, and heptane - were selected to evaluate AFFF/AR's fire suppression efficacy across temperature variations. The findings reveal that hydrophilic groups in high-polarity fuels substantially compromise AFFF/AR stability by accelerating foam drainage, in contrast to non-polar counterparts. Specifically, a 6cm AFFF/AR layer maintained sealing efficacy for only 1410 s on propanol at 97°C, compared to 2410 s on heptane at 98°C. Furthermore, AFFF/AR demonstrates enhanced stability and fire suppression performance when applied to higher-boiling-point fuels. This is evidenced by comparative tests at 60°C: with a 6cm AFFF/AR application, sealing durations reached 2045 s and 2213 s for ethyl alcohol and propanol respectively, accompanied by average cooling rates of 0.49°C/min and 0.66°C/min, and peak cooling rates of 2.08°C/min and 3.26°C/min. Consequently, AFFF/AR exhibits optimal sealing capacity and cooling effects on non-polar, high-boiling-point fuel fires such as heptane pool fires.