This product named photoelectric smoke and heat combination detector (hereinafter called detector) detects the smoke and heat. The principle of detecting smoke is granule in the smoke can reflect infrared light. Infrared diodes are placed in the special chamber.
The chamber can shield external light but doesn’t affect the smoke in it. While there is no smoke, the diode can receive very weak infrared light. When the smoke enters the chamber, the diode can receive more and more light, and the detector can give out an alarm signal when the smoke attains a certain density. To reduce the interference and lower power consumption, the emitting circuit adopts the pulse signal.
The principle of detecting heat is the impedance of the thermistor can change following the temperature. The thermistor reads the temperature from the air it takes in and transmits a signal to the control IC. If the temperature reaches or exceeds the trip point, the detector is triggered. The product in accordance with the networking approach is divided into 2-wire and 4-wire detectors.