An ionization detector detects fire in what stage?

An ionization detector detects fire in what stage?

• A. Incipient
• B. Fully developed
• C. Smoldering
• D. Flaming

Answer: (A)

Ionization detectors sense the onset of flame by detecting the charge ions produced by combustion. When a flame first begins, the hot gases generate ions that increase the current in the detector’s chamber, causing a fast trigger. This makes ionization detectors especially responsive to flaming, fast-burning fires that occur in the early, incipient stage—the moment flames are just starting to form before heavy smoke accumulates. In contrast, smoldering fires (which produce more smoke than flame) are better caught by detectors that are more sensitive to smoke, like photoelectric types, and fully developed fires still trigger ionization detectors but after the initial flame has already established.

Ionization detectors sense the onset of flame by detecting the charge ions produced by combustion. When a flame first begins, the hot gases generate ions that increase the current in the detector’s chamber, causing a fast trigger. This makes ionization detectors especially responsive to flaming, fast-burning fires that occur in the early, incipient stage—the moment flames are just starting to form before heavy smoke accumulates. In contrast, smoldering fires (which produce more smoke than flame) are better caught by detectors that are more sensitive to smoke, like photoelectric types, and fully developed fires still trigger ionization detectors but after the initial flame has already established.