A Concise Analysis of the Technical Principles of Gas Detectors
1. Electrochemical sensors:
-Electrochemical sensors generate a current proportional to the gas concentration by exposing the target gas to a specific electrode. They are mainly used for detecting toxic gases and oxygen.
2. Infrared (IR) sensor:
-Infrared sensors utilize the absorption characteristics of target gases towards specific wavelengths of infrared light. The sensor emits infrared light and then measures the intensity of the light passing through the gas. The reduced light intensity reflects the concentration of gas.
3. Metal oxide semiconductor sensors (MOS):
-MOS sensors use a sensitive metal oxide semiconductor layer to detect gases. When this layer is exposed to certain gases, its electrical resistance changes, revealing the presence and concentration of the gas.
4. Catalytic combustion sensor:
-These sensors have a combustible gas sensitive element that burns on when gas is present. The temperature rise or resistance change caused by this combustion is used to determine the concentration of the gas.
5. Photoionization detection (PID):
-PID sensors use ultraviolet light to ionize gas samples. Then, it measures the current of ions released from the gas, which is proportional to the concentration of the gas.
6. Sound velocity detector:
-These sensors utilize the characteristic that different gases cause sound to propagate at different speeds. Measuring the speed of sound propagation can be used to determine the presence and concentration of specific gases.
7. Chromatographic analysis:
-In more complex devices, gas samples can be analyzed by gas chromatography, which can separate and measure multiple gas components.
Conclusion:
The choice of gas detector usually depends on the application, required sensitivity, required response time, and the specific gas type that may occur. Understanding different technical principles can help choose the most suitable gas detector for a specific application. The constantly evolving technology also means that future gas detectors may become more accurate, reliable, and multifunctional.
