The S600-ExIR3 three wavelength point type infrared flame detector consists of three infrared sensors and an optical filter. The main sensor has the highest sensitivity to the CO2 emission spectrum (4.4 μ m) produced by the combustion of hydrocarbons, while the other two infrared sensors detect background light interference from ambient light and thermal radiation. The detector has multiple signal processing algorithms, combined with logical comprehensive judgment of flame flicker frequency, to minimize false alarms and achieve the best fire detection performance. The special fire signal processing method and multi-sensor detection technology greatly improve the sensitivity and response time of the detector. The detector is suitable for liquid and gas fires, open flames accompanied by smoke, and places where explosions occur.