Application of high sensitivity ultraviolet sensor in flame detection system

     Fire is the burning of an object by giving off light and heat in air or oxygen. Fire plays an important role in the historical stage of human development, it not only brings light and warmth to people, but also brings a lot of suffering and sadness to people. Fire is one of the major disasters threatening public safety and social development, and fire prevention is an important task. In fire prevention, flame detection is a very important part.

     According to the characteristics of fire, flame can be divided into two types: premixed type and diffused type. According to the light characteristics of the flame, there are three kinds of flame detectors currently in use: one is the ultraviolet detector; The other is an infrared detector; The third is a hybrid ultraviolet/infrared detector.

     The fuel and oxide of the premixed flame are fully mixed before the combustion reaction, and the combustion rate is constant, which can only be achieved in a laboratory environment. The oxides of the fuel and diffusion flame are separated from each other before the combustion reaction. Due to the inadequate combustion reaction, the flame is generally yellow and accompanied by smoke. Most of the fires that need to be monitored in actual production and life are mainly diffusion flames.

     Different substances emit different red light and ultraviolet spectra. The flame radiation curve in the flame spectrogram has three bulges, one of which is below 0.28um in the ultraviolet segment and the other two are close to 4.3um and 4.6um in the infrared segment. In all three bands, the surface solar radiation curve is at its lowest point. In general, CO2 and CO released by the hydrocarbon combustion flame can be detected in the center of the filter in the flame detection band with wavelengths of about 4.3 m and 4.4 m.

     Ultraviolet flame detectors detect fires by detecting ultraviolet light produced by burning substances. In addition to ultraviolet flame detectors, there are also infrared flame detectors on the market, also called linear beam smoke detectors. The UV flame detector is suitable for places prone to fire, and can be used in places with strong flame radiation or no smoldering stage in the event of fire. Uv sensors for flame detection require high temperature resistance and high sensitivity of the sensor itself.