Effect of Insect Repellent Bomb on Unwanted Fire

Abstract

A fire detection and alarm system triggered by any element other than fire, such as smoke or a foreign object, is referred to as an unwanted fire alarm. According to the data from the National Fire Agency, as of 2021, the ratio of the number of unwanted-fire dispatches to the total number of 119 dispatches is 17.2%, and the ratio of the number of malfunctions to the number of dispatches triggered by fire detection and alarm systems has remained above 99% for 10 years, resulting in a loss of firefighting resources. In this study, we conducted unwanted fire alarm experiments using insect repellent bombs and implemented the detector and smoke experiments into a three-dimensional numerical analysis to verify the usefulness of the analysis. The smoke concentration at detector points P1 to P3 reached 15%/m in both experiments and numerical simulations, confirming the similarity. For points P4 to P6, the analysis showed that the time at which the smoke concentration started to increase and the time at which it reached its peak were similar in both experiments and numerical simulations. For P7 to P8, the smoke concentration did not reach 15%/m in both experiments and numerical simulations, indicating that the results were similar. The findings of this study suggest that numerical analysis can be used to implement the flow characteristics of domestic smoke generated by an insect repellent bomb, and this study can be used as basic research for analyzing the flow of smoke in a detector or studying the characteristics of a detector through numerical analysis in the future.