What is a light-sensitive fire detector?
When a substance burns, it produces visible or invisible light radiation as it produces smoke and emits heat. A photosensitive fire detector, also known as a flame detector, is a fire detector designed to respond to the light characteristics of the fire, i.e., the intensity of the flame and the flicker frequency of the flame.
According to the flame's optical characteristics, there are two kinds of flame detectors currently used: one is an ultraviolet detector that is sensitive to light radiation with shorter wavelength, and the other is an infrared detector with longer wavelength. The principle of an ultraviolet sensitive detector is that there are two high-purity tungsten wires or molybdenum wire electrodes in the glass bulb of an ultraviolet photosensitive tube.
When the electrode is irradiated by ultraviolet radiation, electrons are emitted immediately and accelerated in an electric field between the two electrodes. These electrons after acceleration (kinetic energy carriers) hydrogen and helium gas molecules and the glass envelope is from collision occurred, a chain reaction caused "discharge", the UV tube by disconnectinto conduction output alarm signal. Infrared detector works: infrared detectors use flame infrared radiation and flash effects to detect fire. Because of the long wavelength infrared spectrum, the smoke particles on the absorption and attenuation of ultraviolet light than shorter wavelengths of visible light and weak, so a lot of smoke in the fire, even from a distance can make the flame infrared photosensitive element response, has the characteristics of short response time.
