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  2. Optical beam smoke detector - Wikipedia

    en.wikipedia.org/wiki/Optical_beam_smoke_detector

    An optical beam smoke detector is a device that uses a projected beam of light to detect smoke across large areas, [1] typically as an indicator of fire. [2] They are used to detect fires in buildings where standard point smoke detectors would either be uneconomical [3] or restricted for use by the height of the building.

  3. Smoke detector - Wikipedia

    en.wikipedia.org/wiki/Smoke_detector

    Smoke detector mounted on a ceiling. A smoke detector is a device that senses smoke, typically as an indicator of fire.Smoke detectors/alarms are usually housed in plastic enclosures, typically shaped like a disk about 125 millimetres (5 in) in diameter and 25 millimetres (1 in) thick, but shape and size vary.

  4. Aspirating smoke detector - Wikipedia

    en.wikipedia.org/wiki/Aspirating_smoke_detector

    An aspirating smoke detector (ASD) is a system used in active fire protection, consisting of a central detection unit which draws air through a network of pipes to detect smoke. [1] The sampling chamber is based on a nephelometer that detects the presence of smoke particles suspended in air by detecting the light scattered by them in the chamber.

  5. Photoelectric sensor - Wikipedia

    en.wikipedia.org/wiki/Photoelectric_sensor

    Conceptual through-beam system to detect unauthorized access to a secure door. If the beam is interrupted, the detector triggers an alarm. A photoelectric sensor is a device used to determine the distance, absence, or presence of an object by using a light transmitter, often infrared, and a photoelectric receiver. They are largely used in ...

  6. Americium-241 - Wikipedia

    en.wikipedia.org/wiki/Americium-241

    With its half-life of 432.2 years, the americium in a smoke detector decreases and includes about 3% neptunium after 19 years, and about 5% after 32 years. The amount of americium in a typical new smoke detector is 0.29 micrograms (4.5 × 10 −6 grains) (about 1/3000 the weight of a small grain of sand) with an activity of 1 microcurie (37 kBq ...

  7. EN 54 - Wikipedia

    en.wikipedia.org/wiki/EN_54

    For smoke detectors according to EN 54-7 and fire detectors with smoke sensor (parts 12, 20 and 30 of EN 54) the test fires TF2, TF3, TF4 and TF5 are used. The EN 54-20 defines the following test fires with reduced fuel quantity for aspirating smoke detectors with enhanced or very high sensitivity (class A or B): TF2A and TF2B; TF3A and TF3B