What type smoke alarm is better
There are two types of smoke alarm according to different types of sensors. They are ion smoke alarm and photoelectric smoke alarm.
The ion smoke detector has an ionization chamber. The intensity of americium 241(Am241)used in the ionization chamber is about 0.8 u Curie, which is in equilibrium under normal conditions. However, if smoke enters into the ionization chamber, the equilibrium relationship will be destroyed, and an alarm will be given out when the smoke concentration reaches a defined value.
There is an optical chamber in the photoelectric smoke detector and an infrared counter tube is installed. When there is no smoke, the infrared receiving tube can not receive the infrared light from the infrared transmitting tube. However, if there is smoke entering into the optical chamber, the smoke is refracted and reflected, the receiving tube will receive the red light. The intelligent alarm circuit judges whether the smoke density is exceeded. If the smoke density value is exceeded, it will give out alarm.
What is the difference of these two types smoke alarm? The ion smoke detector is more sensitive to small smoke particles. In open fire (such as burning newspaper) and fast burning fire, there are more small particles in the air, and the ion smoke alarm will make alarm first than the photoelectric alarm. Photoelectric smoke detector is sensitive to larger smoke particles. When smoldering (such as cigarette igniting sofa), there are more larger smoke particles in the air. At this time, photoelectric smoke detector will make alarm first than ion smoke alarm.
The ion detector has radiation, which will cause bad effects on human health, while the photoelectric detector will not have any impact on health, so photoelectric smoke alarm is always used for home security.