Which detector is activated by small invisible products of combustion?

Which detector is activated by small invisible products of combustion?

• A. Acoustic
• B. Ionization
• C. Magnetic
• D. Photoelectric

Answer: (B)

Ionization detectors are built to respond to the tiny, invisible smoke particles produced by flames. Inside, a small amount of radioactive material ionizes the air between two plates, creating a steady current. When smoke enters, the particles attach to those ions, reducing the current and triggering the alarm. This makes them especially quick to detect flaming fires, where smoke is fine and not yet visible. Photoelectric detectors, by contrast, rely on light scattering and respond best to larger smoke particles from smoldering fires, so they’re slower to react to the small particles from rapid combustion. Magnetic or acoustic detectors aren’t used for detecting these tiny combustion particles, so they aren’t the best match for this scenario.

Ionization detectors are built to respond to the tiny, invisible smoke particles produced by flames. Inside, a small amount of radioactive material ionizes the air between two plates, creating a steady current. When smoke enters, the particles attach to those ions, reducing the current and triggering the alarm. This makes them especially quick to detect flaming fires, where smoke is fine and not yet visible. Photoelectric detectors, by contrast, rely on light scattering and respond best to larger smoke particles from smoldering fires, so they’re slower to react to the small particles from rapid combustion. Magnetic or acoustic detectors aren’t used for detecting these tiny combustion particles, so they aren’t the best match for this scenario.