Studies on the Delay of Smoke Detector Alarm in Underground Engineering

Abstract

Based on numerical simulation, the delay of smoke detector alarm was studied in this paper. The a ir velocity fields and smoke concentrations were introduced in to help to analyze the impact of detector location and air supply velocity on the detector alarm performance. The results revealed that the position of smoke detector had a great influence on the alarm time. Inappropriate installation position delayed the alarm; m eanwhile, the delay was aggravated with larger air inlet velocity. It is of great significance to study the pattern of fire and smoke spread to determine the feasibility of a fire test system. I ntroduction In the underground engineering, the smoke detector is usually installed in the middle position of the roof. And the detector performs well under no wind conditions ( 1 ) . However, when the ventilation and air conditioning system is running, the airflow organization would be different in the room. The smoke would spread with the airflow in the early stage of fire. The smoke detectors can not sent the alarm information timely, w hich would increase the risk of fire (2)(3) . The ventilation and air conditioning system was different according to the location and direction of the wind pi pe. The mounting position of smoke detector should relate to the different air supply mode. This paper s tudied the smoke spread characteristic of two typical underground engineering air supply modes based on t he numerical simulation. The conclusion can guide the mounting position of smoke fire detector.