Classification of smoke detectors

06/01/2023

This smoke detector has 1 ionizing chamber and 1 source of ionizing radiation. This ionizing radiation source contains a small amount of americium-241 (about 1/5000 of a gram). This is the origin of alpa particles (helium nuclei). The ionization chamber is designed with 2 plates 1 cm apart.

Nội dung bài viết

Ion smoke detector
Optical smoke detector
Which type is better to use?

Ion smoke detector

- This smoke detector has an ionization chamber and an ionizing radiation source. This ionizing radiation source contains a small amount of americium – 241 (about 1/5000 of 1 gram). This is the origin of alpa particles (helium nuclei). The ionization chamber is designed with 2 plates 1 cm apart. The battery is placed on one of two voltage plates, one is the positive electrode, the other is the negative electrode. Here alpha particles will be continuously released by americium and knock electrons out of atoms in the air and ionize oxygen and nitrogen atoms in the chamber. These positively charged oxygen and nitrogen atoms will be attracted to the battery plate, and the electrons attracted to these positive plates will create a continuous electric current.

- When smoke enters the ionization chamber, smoke particles attach to ions and neutralize them. That's why it doesn't appear on disk. At the same time, the decrease in plates will trigger the smoke detector to operate.

Optical smoke detector

- In photoelectric devices, smoke can block a beam of light. Therefore, if there is a decrease in light reaching a photocell, an alarm will be generated. These photoelectric devices are very popular, however, when the light is scattered away by smoke particles, a photoelectric cell will trigger an automatic smoke detector.

đầu báo khói

This problem was discovered in a T-shaped room with a light-emitting diode (LED) that can shoot a beam of light on the horizontal bar of the T. At this time, a power cell will be placed below leg of the vertical bar T and generates an electric current when it is exposed to light. In the absence of smoke, the light beam will pass through the top of T and follow an uninterrupted straight line, nor will it attract photoelectric cells placed at the right angle below the beam. Once there is smoke, the light is scattered by the smoke particles and one of them is directed along the longitudinal part of T to attack the corona cells. Once enough afternoon light has entered the cell, the smoke detector will be activated.

Which type is better to use?

- Both types of smoke detectors above give us effective results. Both types above have been tested and certified as UL smoke detectors before being put on the market. With ion smoke detectors, we will see that they respond faster than small detectors. Optical smoke detectors respond faster when encountering smoldering fires.

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