Smart evaluation of building fire scenario and hazard by attenuation of alarm sound field

The audible fire alarm system of the building makes a sharp sound to alert all occupants when fires occur. According to the fire code, the fire alarm should be loud enough to be heard in any corner of the building. Thus, this work explores a smart technology of using alarm attenuation to reveal the fire scene information. Different alarms with frequencies from 500 to 2000 Hz are tested. The propanol pool fires of different sizes and shapes are selected as the detecting targets. Results show that the sound pressure attenuation by the fire plume is positively correlated with the fire scene heat release rate. The sound-pressure attenuation is also greater if the flame thickness is larger along the sound path. Hence, a sound-field fire monitoring model is proposed and verified by experiments using larger wood-crib fire and liquid-pool fire. This work provides a practical sound-based fire monitoring model and helps establish a scientific framework for the smart technology of using the existing audible alarm system to continuously monitor the building fire development.