Introduction to the working principle and application of smoke detectors

Smoke detector, this is a device for detecting fire, etc. The editor of this article will explain the working principle and application of smoke detector.

How Smoke Detectors Work

Ionic smoke

Ionic smoke detectors are point-type detectors. They contain a small amount of radioactive material in the ionization chamber, which can make the air in the ionization chamber become a conductor, allow a certain current to pass in the air between the two electrodes, and the rays make the local air ionize. State, the ion current is formed by the action of voltage, which gives the ionization chamber an effective conductivity. When the smoke particles enter the ionization area, they reduce the electrical conductivity of the air due to the bonding with the ions, forming a weakening of the ion movement. When the conductivity is below a predetermined value, the detector issues an alarm.

Photoelectric smoke

Photoelectric smoke detectors are also point-type detectors, which are developed using the basic property that smoke generated during a fire can change the propagation characteristics of light. According to the absorption and scattering of light by smoke particles. Photoelectric smoke detectors are divided into two types: light-shielding and astigmatism. The working principle of the commonly used photoinductor smoke is detected by the light emitting tube and the receiving tube on the smoke detector. After the light emitting tube emits light, it is received by the receiving tube without hindrance and is transmitted back to the microcontroller. In the process, when the light emitted by the light-emitting tube is blocked by the smoke, the light signal received by the receiving tube is transmitted back to the single-chip microcomputer, and the single-chip microcomputer recognizes that the returned signal is inconsistent with the barrier-free received light signal and reports the fire alarm signal when it is consistent with the pre-stored fire alarm signal. A fault signal is reported when the pre-stored fault signals are consistent.

Infrared beam smoke detection

The infrared beam smoke detector is a linear detector, which is a fire detector that responds to the smoke parameters around a linear narrow strip in the alert range. The main difference between the two types of point-type smoke detectors is that the linear smoke detector divides the beam transmitter and the photoelectric receiver into two independent parts. When using, it is divided into two opposite places, and the middle is connected by a beam. stand up. Infrared beam smoke detectors are divided into two types: through-beam and reflective.

Gas detector

The combustible gas detector uses a high-quality gas sensor, a microprocessor combined with a precision temperature sensor can intelligently compensate for the drift of gas-sensitive components, a wide range of environmental adaptability, stable work, no commissioning, and ceiling-mounted installation, simple installation, convenient wiring, and extensive For home, hotel, apartment and other places with flammable gas for security monitoring. Can detect natural gas, liquefied petroleum gas, artificial gas. The detector operating voltage is DC powered. A pair of relay passive contact signals can be output after the alarm, which is used to control ventilation equipment or provide normally open or normally closed alarm contacts for other equipment. When the flammable gas concentration in the environment reaches the set threshold, it can send out sound and light alarm signals, and can output relay passive contact signals. When the surrounding environment flammable gas concentration drops below the response threshold, the detector in the alarm state will automatically return to the normal working state.

Application of smoke detectors

Because very early smoke detection systems can effectively detect fires in the early stages of fires, they are widely installed in many important places.

Places where service or production cannot be easily interrupted: communication room / computer room / financial data center / clean room / radio or television station / automatic production equipment / bank / electric power facility.

Places where early smoke is difficult to detect: warehouses / refrigerators / gymnasiums / airports / theaters.

Places to avoid business interruption: Communication network center / server room / command and dispatch center / precision medical equipment / MIS room.

Places where maintenance work is difficult: prisons and prisons / cable ducts / return air ducts / nuclear power plants or biochemical protection areas / operating rooms.

Places requiring beautiful or treasured items whose value cannot be estimated: museums / archives / historical buildings / technical facilities / gallery / cathedral.

Specific public places: theatre / church / traffic terminal / nursing home or nursing home / hospital.

The above is an introduction to the working principle and application of smoke detectors. After you understand it, you must have a general understanding of the smoke detectors. I hope that you can choose different detectors according to different requirements when purchasing. .