Infrared detector of flame for conventional systems of intrinsic safety. Certificate ATEX the ex-IInd 1 GD and Cenelec EEx ia IIC T4. For use in interior. His functioning, it is based on the analysis of the wave length. His high resistance to the solar beams, for a functioning without false alarms, makes it ideal for fires of clean fuels as alcohol or methane. His use in facilities must complement with optical or thermal detectors. It recognizes from 4,4 to 4,6 the infrared radiation in a range µm, length of wave issued by a fire with flame.