The Model FL4000 is an advanced multi-spectral infrared (MSIR) flame detector designed to provide superior false alarm immunity with the widest field of view. The FL4000 employs a multi-spectral optical IR sensing array with a sophisticated Neural Network Technology (NNT) system to reliably discriminate between actual flames and the vast majority of false alarm sources (such as arc welding). The FL4000 is designed to detect typical fires such as alcohol, n-heptane, gasoline, jet fuels and hydrocarbons. In addition, the FL4000 can see through dense smoke produced by diesel, rubber, plastics and lube oil fires.