There are many brands of flame detectors. At present, the flame detector based on the principle of radiant energy is the most widely used and more effective method of flame detection. The principle of measuring the intensity of radiation is to use the probe to receive the radiation emitted by the flame and judge the existence or absence of the flame according to its strength. Because of the different detection bands, it can be divided into ultraviolet, visible, infrared and full radiation flame detection.
The flame detection signal comes from ultraviolet detectors and smoke detectors. The flame detector has three separate detection tubes for detecting ultraviolet radiation at 180 - 260 Angstrom. When the radiation of the flame reaches the cathode of one of the probes, the electron beam radiates. The electron beam acts on the ionized gas filled with the detection tube, thus emitting more electrons and producing avalanche conditions. More electrons are released, producing a transient electron flow between the cathode and the anode. The rate of instantaneous electron flow (pulse) proportional to the intensity of ultraviolet radiation occurs repeatedly. The frequency of the pulse is changed into voltage in the detector and transmitted to the controller.