Which detector uses ionization of air between two electrodes using a small amount of radioactive material to sense smoke?

Which detector uses ionization of air between two electrodes using a small amount of radioactive material to sense smoke?

• A. Ionization Smoke Detector
• B. Photoelectric Smoke Detector
• C. Beam Detector
• D. Radiant Energy Detector

Answer: (A)

Ionization-based smoke detectors rely on ionizing the air between two closely spaced electrodes with a tiny sealed radioactive source. This ionization creates a steady electrical current. When smoke enters the chamber, the smoke particles attach to the ions, reducing the current and triggering the alarm. This method responds quickly to flaming fires, which produce many small particles that easily interfere with the ion flow. The radioactive material is typically a sealed amount of americium-241, chosen because it stays contained and safe under normal use, with regulatory controls for handling and disposal. Other detector types detect smoke through different means: photoelectric detectors use light and detect smoke by scattered light, beam detectors project a beam across a space and trigger when the beam is interrupted, and radiant energy detectors focus on heat or radiant energy rather than ionization.

Ionization-based smoke detectors rely on ionizing the air between two closely spaced electrodes with a tiny sealed radioactive source. This ionization creates a steady electrical current. When smoke enters the chamber, the smoke particles attach to the ions, reducing the current and triggering the alarm. This method responds quickly to flaming fires, which produce many small particles that easily interfere with the ion flow. The radioactive material is typically a sealed amount of americium-241, chosen because it stays contained and safe under normal use, with regulatory controls for handling and disposal. Other detector types detect smoke through different means: photoelectric detectors use light and detect smoke by scattered light, beam detectors project a beam across a space and trigger when the beam is interrupted, and radiant energy detectors focus on heat or radiant energy rather than ionization.