Explain about Ionization Smoke Detector?

The ionization smoke detector is widely used. Its capability to detect smoke originating from fire is best utilized for clean-burning fires that produce small particles during combustion.

The ionization smoke detector consists of an alpha particle producing a radioactive source, a smoke chamber, and charged detector plates.

  • The alpha source causes the air within the smoke chamber to become ionized and conductive
  • As smoke particles enter the smoke chamber, the smoke particles attach themselves to the ionized air molecules and the air in the chamber becomes less conductive
  • When the air conductivity within the chamber drops below a predetermined level, the alarm is triggered
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In addition to vignesh’s post, the same is detailed by the below diagram

Now a days, in many EU countries the ionization type detectors are banned as they contain the radioactive source (problem of disposal). Also, they offer lots of nuisance alarm due to their design limitations.

Optical type smoke detectors are now the replacement for the old ionization type detectors