The FL10 flame detector is capable of detecting a flame produced by a fire within its field of vision in a few seconds. The operating principle is based on the detection of infrared (IR) radiation emitted by a flame. Optical filters have been applied to let infrared radiation through and block other light radiation. The instrument is therefore immune to sunlight, artificial light, ultraviolet rays, X-rays and gamma rays. The circuitry and advanced electronic components used make the detector highly efficient while effectively safeguarding against false alarms. The instrument housing is constructed in self-extinguishing polycarbonate, with particularly robust attributes, and offers practical installation.