Infrared gas detector working principle

Infrared gas detector, the full name is infrared optical gas detector, mainly detects gas concentration through the core equipment Infrared gas sensor. It works according to the principle of Lambert-Beer’s law and is based on different gas molecules. Near-infrared spectroscopy selects absorption characteristics and uses the relationship between gas concentration and absorption attenuation intensity (Lambert-Beer law) to identify gas concentration components.

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Infrared gas detector working principle

Infrared gas detector working principle: The gas to be measured is continuously passed through a container of a certain length and volume. The molecules composed of different atoms will have unique vibration and rotation frequencies. When the sensing wavelength of the infrared gas detector is consistent with the gas to be measured, When the absorption spectral lines match, infrared energy absorption will occur, causing changes in infrared light intensity. The light intensity attenuation of infrared light after passing through the gas being measured satisfies the Lambert-Beer law. The greater the gas concentration, the greater the intensity of the infrared light. , the attenuation of light is also greater. At this time, the gas concentration can be measured only by measuring the change in infrared attenuation intensity.

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Advantages and Disadvantages

The advantages of infrared gas detectors include long service life (5 years of life), high sensitivity, good stability, non-toxic, less interference from ambient temperature and humidity, and independence from oxygen. Infrared gas detectors can accurately distinguish trace levels of PPB-level gases or PPM-level gases, and the accuracy is as high as within 1%. At present, infrared gas detectors are widely used in scientific research experimental gas analysis, hazardous chemical gas leak detection, factory boundary safety inspections, air pollution detection and other scenarios.


Disadvantages of infrared gas detectors: This technology is a bit expensive in principle. Compared with conventional electrochemistry, semiconductor and catalytic combustion gas detectors are much more expensive in principle. Therefore, friends with a low budget can only consider other conventional detection principles in addition to PID and infrared.

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What gases are suitable for infrared gas detectors?

Infrared gas detectors are suitable for measuring most flammable gases, such as measuring high concentrations of methane, ethanol, propane, ethane, cyclohexane, hexahydrobenzene, cyclopentane, propylene, acrylonitrile, carbon dioxide, nitrogen dioxide, hexahydrobenzene, Sulfur fluoride, carbon monoxide, sulfur dioxide, ammonia, laughing gas, n-ethane, n-pentane, valeric acid, isobutanol, methyl bromide and other gases. In addition, infrared gas detectors are also suitable for measuring most volatile organic gases, such as TVOC, VOCs, VOC, toluene, xylene and other gases.