# Multi-Sensor Photoelectric Fire Alarm Device Implementation for Early Fire Detection in Campsites
## 4 Experiments and Results  
This section describes an experimental study that assesses the efficacy of the proposed multi-sensor photoelectric fire detector in a simulated camping environment, as shown in Figure 17. The experimental setup involved a shower booth tent as a stand-in for a typical camping site. In this controlled environment, a fire was initiated to test the detector response. Both a standard photoelectric fire detector [Stand-alone Photoelectric Type 2 Fire Detector by Hyundai Fire Protection Industry] and the proposed multi-sensor photoelectric fire detector were installed at the apex of the shower tent, adhering to common fire detector placement practices. Safety precautions were strictly followed, including the use of flame retardants, readily available fire extinguishers, and the presence of trained safety personnel throughout the experiment.  
The experimental results, as illustrated in Figure 18, indicated a temperature increase from an initial temperature of 40 \({}^{\circ}\)C to a peak at 45 \({}^{\circ}\)C. Concurrently, the humidity level depicted in Figure 19 began at 40% and increased to 50% due to the evaporation at the ignition point shown in Figure 20 before gradually decreasing to 29%. The commercially available photoelectric fire detector took approximately 3 min and 28 s to detect the fire after it was ignited, and the average analog value of brightness recorded by the light sensor at that time was approximately 890.  
Figure 17: Experimental Environment.  
Figure 18: Temperature variation data from DHT11.  
Figure 20 displays two graphs: red and blue. The red graph in Figure 20 illustrates the real-time adjustments of the fire alarm threshold based on the temperature and humidity data in Figures 18 and 19, as computed using the algorithm shown in Figure 16. The blue graph in Figure 20 shows the actual light levels detected by the light sensor. A fire is identified when the threshold value depicted in the red graph drops below the light sensor's reading (represented in the blue graph), and it is then registered as a new alarm.  
The results revealed that conventional photoelectric fire detectors operate with a threshold of an analog value of approximately 890. However, in the proposed smoke detector, the threshold was adjusted to between 900 and 920 under normal, non-fire conditions. When fire conditions were detected, the threshold rapidly decreased to facilitate quicker fire detection. This indicates that maintaining a stable threshold value when the temperature and humidity remain relatively constant does not significantly increase the likelihood of false alarms. The detailed experimental results are provided in the table in Appendix A, which displays the temperature, humidity, brightness, and threshold values recorded by the fire alarm system between 17:55:40 and 17:56:28. The table also compares the fire detection time of our multi-sensor photoelectric fire detector with that of a commercially available model. Furthermore, the proposed fire alarm system, which considers humidity, was able to detect a fire approximately 40 s (20%) faster than a conventional alarm system, requiring approximately 2 min and 48 s from the onset of the fire. The reduced response time is a significant improvement, particularly in terms of enhancing evacuation times during a fire.  
Table 4 presents a comparative analysis between the proposed and existing detection systems based on various criteria, such as cost, error rate, accuracy, and the need for pre-learning for operation. The proposed multi-sensor fire alarm exhibited improvements in these comparison metrics compared with the other fire alarm types. For instance, a  
Figure 19: Humidity variation data from DHT11.  
Figure 20: Alarm time difference between the commercially available photoelectric fire detector and the proposed multi-sensor photoelectric fire detector.  
MOSFET-based fire alarm [18] exhibited a high error rate because of its sensitivity to temperature changes.