gas detectorThe key components are:Gas sensor。 Gas sensors can be divided into three categories in principle. Gas sensors with physicochemical properties, such as semiconductors, catalytic incineration, solid thermal conductivity, photoionization, etc. Gas sensors with physical properties are used, such as thermal conductivity, optical coherence, infrared absorption, etc. Utilize the electrochemical characteristics of gas sensors, such as current type, potential type, etc.
gas detectorDetection principle:
1. For the detection of the lower explosion limit of common combustibles, catalytic incineration detectors are commonly used. The principle is that the center of the sensor is a Wheatstone bridge, and one of the bridge arms has a catalyst. When in contact with flammable gas, flammable gas burns on the catalyst's bridge, and the resistance of the bridge changes, while the resistance of the other bridges remains unchanged. The output of all circuits then changes, the change is related to the concentration and composition of the flammable gas, and the combustion gas is checked after calibration.
2. For the detection of common toxic gases, especially inorganic toxic gases, special sensors are generally used for detection and quantitative detection. Most of these sensors are point chemical sensors. Electrochemical sensors are usually three-electrode situations. In this way, the gas can provide the appropriate bias value on the working electrode. The sensor completes the selective response, that is, the qualitative response, through the catalytic action of the reference electrode and the working electrode. The current generated in the circuit is proportional to the gas concentration to complete the quantitative response. Oxygen sensors are generally double-electrode sensors, and the detection principle is similar to that of three-electrode sensors, but the output of three-electrode sensors is more stable and has a longer life.
3. For the detection of volatile toxic gas, choose to test in the morning. However, due to the limited types of detection tubes and low accuracy, the application of detection tubes is affected. At present, the more popular method is to choose the photoionization detection method. The principle is that after the target gas is irradiated by ultraviolet lamp, the sensor collects and forms an electric current and separates it from the target gas. For example, a sensor collects an electric current and forms an electric current, which is inversely proportional to the concentration of the target gas. Then, the quantitative detection of organic volatile gases was completed, and the ion level was determined, so that the method had high resolution and fast echo time.