Alarm Thresholds For Smoke Detector Modeling

Abstract

Models have been used to estimate smoke detector alarm times by calculating smoke optical densities resulting from fires and correlating the smoke value to an alarm threshold of the detector. This work evaluated the use of smoke optical densities outside a detector as criteria for predicting smoke detector responses. Results are presented for optical density alarm thresholds corresponding to when 20, 50 and 80 percent of the detectors had alarmed in full-scale tests. The data showed that there was a large amount of variability in the measured smoke optical density values outside a detector at the time of alarm. Major variables evaluated included detector type, fire type and nominal detector sensitivity. This evaluation also examined experimental smoke optical density data at the time of detector alarms and compared these smoke values to alarm thresholds recommended in the literature.