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
