What technology do photoelectric smoke alarms use to detect smoke?

Photoelectric smoke alarms utilize a light beam and photocell to detect smoke. In these alarms, a light source emits a beam of light, which is typically positioned away from the photocell sensor. Under normal conditions, the light travels unobstructed through the sensing chamber. However, when smoke particles enter the chamber, they scatter the light beam, causing some of the light to redirect toward the photocell. This activated sensor triggers the alarm, indicating the presence of smoke.

This technology is particularly effective at detecting smoldering fires, which produce a significant amount of smoke before reaching open flames. In contrast, ionization alarms rely on a very different detection method involving the ionization process, while heat sensing technology reacts to temperature increases, and acoustic feedback relates to audio signals rather than smoke detection. The effectiveness and operational mechanism of photoelectric smoke alarms make them a vital component of fire safety systems.