What types of optical flame detectors are available?
There are various types of optical flame detector that utilise the various spectral bands that are emitted by the fire: • UV – single sensor type. • IR – single sensor type. • UV/IR – dual sensor type. • IR2 – dual IR sensor type. • IR3 – Triple IR sensor type. • CCTV – Image processing type. • Multi IR – multi IR sensor type The unique flame radiation spectral pattern allows several spectral ranges to be employed simultaneously in the various detection devices. Optical Flame Detectors usually employ several optical sensors, working in specific spectral ranges (usually narrow bands) that record simultaneously the incoming radiation at the selected wavelengths. The signals recorded by each sensor are analyzed according to a pre-determined technique that includes one or more of the following: • Flickering frequency analysis. • Threshold energy signal comparison. • Mathematical ratios and correlations between various signals. • Comparator techniques (and-gate techniques). • Correlation to
