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Which one of the following is not detected by fire detectors ?

June 1, 2025 by rawan239

Which one of the following is not detected by fire detectors ?

Radiation

Heat

Light

Smoke

This question was previously asked in

UPSC CISF-AC-EXE – 2022

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Fire detectors are designed to detect signs of fire: Smoke, Heat, or specific types of Radiation (like UV or Infrared) emitted by flames. Standard fire detectors do not typically detect other forms of radiation, such as X-rays or nuclear radiation, which are not characteristics of a typical fire. While flame detectors detect UV/IR radiation from the fire itself, the term ‘Radiation’ alone is broad and can encompass types not related to fire. Given the other options (Heat, Light, Smoke) are directly detected by common types of fire detectors (heat detectors, smoke detectors, flame detectors), ‘Radiation’, interpreted broadly (e.g., X-rays), is the phenomenon not typically detected by fire detectors.

– Fire detection methods include sensing smoke, heat, and flame.
– Flame detectors specifically detect UV and IR radiation from flames.
– Standard fire detectors do not detect other forms of radiation like X-rays or nuclear radiation.

Common types of fire detectors are smoke detectors (ionization and photoelectric), heat detectors (fixed temperature and rate-of-rise), and flame detectors (UV, IR, or UV/IR). While ‘Light’ could refer to visible light (less common for primary detection than UV/IR), and ‘Radiation’ specifically refers to the UV/IR detected by flame detectors, the option ‘Radiation’ alone is broad enough to include types not related to fire, making it the least likely phenomenon detected by *fire* detectors in a general sense. Assuming ‘Radiation’ is not limited to UV/IR from flame, it is the correct answer.

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