Infrared (IR) absorption is a detection technology that measures gas concentration by detecting the absorption of specific infrared wavelengths by target gas molecules. This method uses the Beer-Lambert law and provides selective detection based on molecular structure.
The principle relies on gas molecules absorbing specific IR wavelengths, with absorption proportional to gas concentration. This technology offers selective detection with minimal cross-sensitivity, requires no oxygen for operation, is not susceptible to catalyst poisoning, and provides long sensor life.
IR absorption is suitable for many hydrocarbon gases, particularly methane detection. Types include single wavelength (measures absorption at one wavelength), dual wavelength (compares absorption at two wavelengths - reference and measurement), open path (detects gas clouds over distances), and point detection (measures at specific location).
Advantages include selective detection with minimal cross-sensitivity, no oxygen requirement, immunity to catalyst poisoning, long sensor life, and suitability for many hydrocarbon gases. However, limitations include requiring IR-transparent gases, some gases don't absorb IR well, potential effects from environmental conditions, and higher cost than catalytic sensors.
Comparison with catalytic sensors shows IR offers selectivity, no oxygen needed, and longer life, while catalytic sensors provide lower cost and detect all flammable gases but require oxygen. The choice depends on application requirements, environmental conditions, and budget constraints.