Texas Fire Alarm License Practice Test

Which sensor excels at detecting thick, visible smoke particles?

1. Photoelectric

2. Ionization

3. Thermal

4. Ultrasonic

The correct answer is: Photoelectric

The photoelectric sensor is particularly effective at detecting thick, visible smoke particles because it operates based on the scattering of light. When smoke particles enter the chamber of a photoelectric sensor, they scatter the light beam emitted by a light source. This scattering triggers the alarm. Because photoelectric sensors are sensitive to larger smoke particles that are often indicative of smoldering fires, they are especially suitable for environments where such smoke is likely to occur. In contrast, ionization sensors work best with fast-burning fires that produce smaller, less visible particles, while thermal sensors measure changes in temperature and do not directly detect smoke. Ultrasonic sensors, on the other hand, are primarily used for detecting motion or sound rather than smoke, making them unsuitable for fire detection purposes. Thus, the photoelectric sensor is the optimal choice for detecting thick, visible smoke particles effectively.