Which detector type is commonly used in smoke detectors to sense smoke via light?

• A. Photoelectric cell devices
• B. Inconel loop
• C. Optical detectors
• D. Systron Donner

Answer: (A)

Smoke detectors that sense smoke with light rely on a photoelectric sensor. In this setup, a light beam is directed into a chamber and a photodetector sits so it normally receives little light. When smoke enters the chamber, the particles scatter the light, and some of it is redirected toward the detector, triggering the alarm. This method is particularly effective for smoldering fires that produce lots of fine particles. The specific detector type used for this light-based sensing is photoelectric cell devices, which are a form of optical detectors. Other options don’t describe this light-based approach: an inconel loop relates to a heating element used in other flame sensing contexts, and while optical detectors is a broad term, the commonly used light-based smoke detector is the photoelectric cell device. Systron Donner is a brand name, not the detector type itself.