Energy-efficient monitoring system for fire extinguishers

Abstract: Fire extinguishers are a requirement for fire safety in every type of building today. The effectiveness of a fire extinguisher is however dependent on it not leaking and keeping the pressure. To assure that this is not the case, maintenance is recommended at regular intervals, by the owners themselves at monthly intervals, and once per year by professionals. This however leaves the fire extinguishers unmonitored for long periods of time, up to a year at worst, which could prove to be a fatal problem. The goal of the work presented in this report is to successfully automate the regular maintenance of fire extinguishers such that only regular service is needed. Different methods of monitoring the pressure of fire extinguishers were explored, such as mounting a small camera module and using computer vision to detect changes in the pressure gauge. The use of strain gauges to continuously weigh the fire extinguisher to detect any changes was also examined. To monitor tampering the use of an inertial measurement unit as well as other types of sensors like a reed switch were explored. The final solution, using a small camera module combined with a low-power MCU (Micro Controller Unit) and a reed switch, was able to detect small changes in pressure accurately. It was also efficient enough to be operational for at least ten years off of a single standard AAA battery.