Ionization Detectors
Ionization Detectors works by forming an electrical path inside the
smoke detector with a very small amount of radioactive material. When
smoke enters the detector, the
smoke molecules attach themselves to the ions and change the electrical
current. This change in the
current triggers the alarm.
Photoelectric Detector
Photoelectric Detectors work by containing a light source (like a small light
bulb) and a photocell that is activated by light. Usually, the light never reaches the photocell. However, when
smoke fills the
smoke detector, the
smoke reflects the light towards the photocell. The photocell than triggers the alarm.
Which is Better?
Both of these types of
smoke detectors are designed to detect
smoke in the air. The ionization detector responds slightly quicker to flaming fires (like draperies), with smaller particles of combustion, while the photo-electric detector responds quicker to smoldering fires (like a cigarette.) However, both types of
smoke detectors have to pass the same test to be certified as a UL
smoke detector, and both will warn you in almost all cases of fires.