Which type of smoke detector is triggered by the presence of visible smoke particles?

Photoelectric smoke detectors are specifically designed to respond to the presence of visible smoke particles. These detectors utilize a light source and a photodetector; when smoke enters the detector, it scatters the light beam, triggering the alarm. This type of smoke detector is particularly effective in detecting smoldering fires, which produce a large amount of smoke before flames become visible.

In contrast, ionization smoke detectors operate based on the ionization of air within a sensing chamber and are more sensitive to fast-flaming fires, which usually produce little smoke in the early stages. Heat detectors do not sense smoke at all; instead, they respond to changes in temperature, making them suitable for areas where smoke alarms might produce false alarms. Combination smoke detectors utilize both ionization and photoelectric technologies to provide enhanced safety by sensing both types of fires more effectively.