External Exposure Experiment and Condensation Detection Method for Air Sampling Smoke Detectors in Freezer Storage

In this study, a pipe temperature characteristics test and a condensation detection method were conducted for each area of the air sampling smoke detector in the freezer. Among the temperature gradient experiments for each zone, the maximum temperature differences were as follows: Zone 1: –6.8 ℃, Zone 2: –0.7 ℃, Zone 3: –0.3 ℃, and Zone 4: 5.8 ℃, indicating the largest temperature difference between the outdoor contact part and the area exposed to the wind side of the cooler. In areas with large temperature gradients, condensation and freezing occurred in the air-sampling smoke detector pipe. In an experiment to detect condensation in an air suction-type pipe using a pressure sensor, a measurement of 1,058 mV was recorded by the pressure sensor during the operation of an air-sampling smoke detector fan with a standardized airflow. When freezing occurred at the pipe inlet due to condensation, we confirmed that the voltage increased by 1,069 mV in one location, 1,099 mV in three locations, and 1,110 mV in five locations. Accordingly, we believe that by transmitting the voltage signal from the pressure sensor due to the pressure drop caused by condensation, the flow rate and pressure status of the pipe can be monitored, allowing for maintenance based on abnormal signals.