This product named Photoelectric detector (hereinafter called detector) refracts infrared light by a couple of particulate matter. Infrared diodes are placed in the special chamber. The chamber can shield external light, but don’t affect the smoke getting into it. when no smoke, the diode canreceive very weak infrared light. when the smoke entering the chamber,diode can receivemoreand more light,whenthe smoke attains the certain density, thedetector cangiveout alarm signal.In order toreduce the interference and lower powerconsumption,the emitting circuit adoptsthe pulse signal.The detectoradopts the special structure design , hasthe dust proof,mothproof and anti outsidelight interference feature etc. The detectoris suitablefor detect the smoke in house, shop,hotel, restaurant, ofce building,school,bank, library, computer house and storehouse etc.