Associate Safety Professional Practice Exam

Why are fixed temperature heat detectors not suitable for rapidly developing fires?

1. They are too sensitive

2. They have a time lag in reacting to temperature

3. They can only detect smoke

4. They require substantial airflow

The correct answer is: They have a time lag in reacting to temperature

Fixed temperature heat detectors are designed to activate when the temperature reaches a certain predetermined threshold. They detect heat based on the principle that a fire will eventually cause a significant increase in temperature. However, in cases of rapidly developing fires, the environment may produce extreme temperature increases in a very short time period. These detectors have a time lag in reacting to temperature changes because they wait for the temperature to reach a set point before activating. If a fire develops quickly, the conditions may escalate beyond the detector’s threshold before it has a chance to respond. This lag in detection can delay alarm activation, allowing the fire to spread before effective measures can be taken. Thus, while fixed temperature heat detectors can be effective in many fire situations, their design inherently makes them less suitable for rapidly developing fires where quick detection is crucial.