This product detects the smoke by a couple of infrared diodes. The principle of detecting is granule in the smoke can reflect infrared light. Infrared diodes are placed in the special chamber. The chamber can shield external light￡? but don&acute;t affect the smoke into it. While have no smoke￡? the diode can receive very weak infrared light. When the smoke entering the chamber￡? diode can receive more and more light￡? when the smoke attains the certain density￡? the detector can give out alarm signal. In order to reduce the interference and lower power consumption￡? the emitting circuit adopts the pulse signal. The detector adopts the special structure design and ASIC￡? has the dustproof￡? mothproof and anti outside light interference feature and etc. The detector is suitable for detecting the smoke in house￡? shop￡? hotel￡? restaurant￡? office building￡? school￡? bank￡? library￡? computer house￡? storehouse and etc.                                    Features            The detector works once connectd to DC power directlyOperation Indicator flashing signifies detector working normally and alarmingIndicator on signifies detector alarmingBuilt-in a couple of output contact￡? which keep close when normally and disconnect after alarmAuto-reset when no smoke existing nearby. Intalling with mounting baseInfrared photoelectronic sensorAuto resetIntelligent logic controlNetwork output / LED indicating alarmAnti-light￡? mothproof￡? dustproofStrong adaptability for circumstanceSMT design￡? high stabilityStain steelers shield￡? ANTI-RFI (20V/m - 1GHz)                                                            Specifications            Operating Voltage    DC 12V    <br>Static Current    2mA    <br>Alarm Current    10mA    <br>Alarm Indication    Red LED on    <br>Operating Temperature    -10?? ~ +50??    <br>Operating Humidity    95%RH    <br>ANTI - RFI    10MHz - 1GHz 20V/m    <br>Detecting Area    80 square meter (with the installation height of 6m - 12m)￡? and 60 square meter (with the installation height less than 6m)    <br>Alarm Output    Relay output N.C.￡? DC 28V￡? 100mA    <br>Dimension    104mm dia. x 51mm deep    <br>Sensitivity    I LEVEL    <br>Color    White    <br>Weight    218g    <br>                                                            Package Includes            1 x First Alert 20 Square Meters Home Security Smoke Detector Alarm