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An americium container from a smoke detector. An ionization smoke detector uses a radioisotope, typically americium-241, to ionize air; a difference due to smoke is detected and an alarm is generated. Ionization detectors are more sensitive to the flaming stage of fires than optical detectors, while optical detectors are more sensitive to fires ...
The ionization chamber has found wide and beneficial use in smoke detectors. In an ionisation type smoke detector, ambient air is allowed to freely enter the ionization chamber. The chamber contains a small amount of americium-241, which is an emitter of alpha particles which produce a constant ion current. If smoke enters the detector, it ...
In 1965 Pearsall began the long process to develop and market a home smoke detector powered by a battery which could be easily installed and replaced. [ 7 ] [ 8 ] These first units were dubbed "SmokeGard 700"; [ 9 ] Pearsall was awarded a design patent for this in 1973, [ 10 ] and began mass-producing them in 1975. [ 8 ]
Ionization chamber type smoke detectors detect particles of combustion that are invisible to the naked eye. This explains why they may frequently false alarm from the fumes emitted from the red-hot heating elements of a toaster, before the presence of visible smoke, yet they may fail to activate in the early, low-heat smoldering stage of a fire.
Ionization-type smoke detectors are gaseous ionization detectors in widespread use. A small source of radioactive americium is placed so that it maintains a current between two plates that effectively form an ionisation chamber. If smoke gets between the plates where ionization is taking place, the ionized gas can be neutralized leading to a ...
Flame ionization detectors cannot detect inorganic substances and some highly oxygenated or functionalized species like infrared and laser technology can. In some systems, CO and CO 2 can be detected in the FID using a methanizer , which is a bed of Ni catalyst that reduces CO and CO 2 to methane, which can be in turn detected by the FID.