NCIDQ IDFX Practice Exam

Which type of detector is least effective with smoldering fires?

1. Photoelectric detector

2. Ionization detector

3. Flame detector

4. Rise-of-temperature detector

The correct answer is: Flame detector

A flame detector is primarily designed to identify the actual presence of flames, detecting the light or heat emitted by a flickering flame. However, smoldering fires typically produce less visible light and can often generate significant smoke before open flames develop. This characteristic makes flame detectors less effective in these situations, as they rely on the detection of radiant energy from flames, which may not be present until the fire transitions from a smoldering state to an actual flame. In contrast, photoelectric detectors are more responsive to the smoke produced by smoldering fires, which tend to emit larger particulate matter. Ionization detectors can also detect smoke but are generally more effective with fast-burning fires. Rise-of-temperature detectors respond to a rapid increase in temperature, which may not occur during the initial stages of a smoldering fire. Thus, while flame detectors have their advantages in specific fire scenarios, they lack the necessary sensitivity to detect smoldering fires effectively.