## 6 Summary and Conclusions  
In this experimental study, a fire-extinguishing performance evaluation of a compressed air foam system was conducted with different mixing ratios of the air-to-aqueous foam solution with the AFFF of 3% and while discharging the foam at a speed of 200 L/min. A summary of the findings and a conclusion are given below.  
1. The expansion ratio and the 25% drainage time by the CAFS showed excellent performance compared to the GAMS. From these characteristics of the foam by the fire-extinguishing system, it can be found that the fire-extinguishing performance by the CAFS is better than the GAMS on oil fires. Moreover, an economic effect can be expected because there is an advantage to maximizing efficiency by minimizing water usage.
2. The compressed air foam system with the air-to-aqueous foam solution of 1:4 showed a net fire suppression time of 34 s in the results measured by the thermocouple and a net fire suppression time of 21 s in the measured results obtained from the heat flux.
3. The compressed air foam system with the air-to-aqueous foam solution of 1:7 showed a net fire suppression time of 30 s in the results measured by the thermocouple and a net fire suppression time of 18 s in the measured results obtained from the heat flux.
4. The compressed air foam system with the air-to-aqueous foam solution of 1:10 showed a net fire suppression time of 45 s in the results measured by the thermocouple and the net fire suppression time of 25 s in the measured results obtained from the heat flux.
5. In conclusion, it was found that the fire-extinguishing performance of the compressed air foam system with the air-to-aqueous foam solution of 1:7 and with aqueous film-forming foam of 3% at an identical flow rate of the discharging foam at a speed of 200 L/min is most effective.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Contents**} & \multicolumn{2}{c}{**Results for the Aging Test**} & \multicolumn{1}{c}{**Specification [10]**} \\ \cline{2-5}  & **Before** & **After** & \\ \hline \multirow{5}{*}{
\begin{tabular}{c} General \\ material \\ properties \\ \end{tabular} } & Specific gravity & 1.04 & 1.04 & \(\leqslant\)1.03 \(\pm\) 0.02 at 20 \({}^{\circ}\)C \\ \cline{2-5}  & Kinematic viscosity & 7 & 7 & at 50 \({}^{\circ}\)C \\  & (cSt) & 23 & 21 & \(\leqslant\)200 & at 20 \({}^{\circ}\)C \\  & 83 & 76 & & at \(-\)10 \({}^{\circ}\)C \\ \cline{2-5}  & \multirow{2}{*}{Freezing point (\({}^{\circ}\)C)} & \multirow{2}{*}{\(-\)12.5} & \multirow{2}{*}{\(-\)12.5} & Below 2.5 \({}^{\circ}\)C than the lower bound of the service temperature of \(-\)10 \({}^{\circ}\)C \\ \cline{2-5}  & & & & \multicolumn{1}{c}{} \\ \cline{2-5}  & Hydrogen ion & \multirow{2}{*}{7.8} & \multirow{2}{*}{7.8} & More than 6.0 or less than 8.5 \\  & concentration (pH) & & & & \\ \hline \hline \end{tabular}
\end{table}
Table 4: Comparison of the general material properties for the synthetic surfactant foam of 3%.  
It was confirmed that the net fire suppression time by the compressed air foam system with the air-to-aqueous foam solution of 1:4 with the synthetic surfactant foam of 3% and at a flow rate of the discharging foam at a speed of 200 L/min as obtained from both the thermocouple and the heat flux is shorter than that with the AFFF of 3%.  
This work was supported by the Incheon National University Research Grant in 2011.  
In this paper, the overall experimental plan in order to investigate the fire-extinguishing performance of the CAFS was prepared together by [PERSON] and [PERSON] as a co-first author. The manuscript was written by [PERSON].  
The authors declare no conflict of interest.