What is Dual IR/IR Flame Detection?
In order to eliminate false alarms, dual wavelength technology combining two narrow spectral ranges in the near IR spectral band had been selected. Since hydrocarbon flames emit energy of a continuous nature in the near IR (0.9micron – 3.0micron) and a unique peak at the 4.3micron – 4.5micron (caused by a hot CO2 fire product), these features are the “heart” of most dual IR detectors. Common dual IR flame detectors employ two narrow bands 0.9micron and 4.3micron for fire signal analysis or a combination of short wavelength 0.8-1.1micron and long wavelength 14-25 micron IR channels. Some of the dual IR detectors include, in addition to one near IR channel for fire detection, a channel for the background detection in the 4.7-16micron IR band. However, an additional approach to dual IR detection technology has emerged in the last years, where the fire main spectral characteristic feature at 4.3 – 4.5 micron is analyzed thoroughly. The basis to this analysis is the “differential spectral”
