Fire alarms radiation detectors

In Chapter 5.4, optical ultraviolet radiation sensors are described, including UV-enhanced silicon-based pn diodes, detectors made from other wide band gap materials in crystalline or polycrystalline form, the latter being a new, less costly alternative. Other domestic applications are personal UV exposure dosimetry, surveillance of sun beds, flame scanning in gas and oil burners, fire alarm monitors and water sterilization equipment surveillance. 

Am), which sends a stream of radiation to a detector. The smoke alarm goes off when this stream is interrupted by smoke—or steam, which is why smoke detectors in the kitchen can have an annoying habit of going off even when there isn t a fire. But smoke detectors have saved an impressive number of lives, so resist the temptation to disable the annoying smoke detector and provide the kitchen with better ventilation instead. 

Multi-band fire detector monitors monitor several wavelengths of predominate fire radiation frequencies by photocells. They compare these measurements to normal ambient frequencies through micro processing. Where these are found be above certain levels an alarm is indicated. False alarms may even be "recognized"... 

The use of two separate electrical or mechanical zones of detectors, both of which must be actuated before the confirmation of a fire or gas detection. For example, the detectors in one zone could all be placed on the north side of a protected area, and positioned to view the protected area looking south, while the detectors in the second zone would be located on the south side and positioned to view the northern area. Requiring both zones to be actuated reduces the probability of a false alarm activated by a false alarm source such as welding operations, from either the north or the south outside the protected area. However this method is not effective if the zone facing away from the source, sees the radiation. Another method of cross zoning is to have one set of detectors cover the area to be protected and another set located to face away from the protected area to intercept external sources of nuisance UV. If welding or lighting should occur outside the protected area, activation of the alarm for the protected area would be inhibited by second... 

Ultraviolet Detectors—Sound an alarm when the radiation from fire flames are detected. 

Flame detectors are not affected by airflow characteristics. They are suitable for inside or outside use, but they must be shielded from external sources of ultraviolet or infrared radiation such as welding arcs, lightning, or radiating black bodies such as hot engines or manifolds. Ideally, the fire detection system should have more than one fire eye detecting a fire so that false alarms can be weeded out. Flame detectors can be... 

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