FLIR's gas detection cameras help to "see" hundreds of invisible gases quickly and safely, but not all types of gases can be imaged with optical gas imaging (OGI cameras). Understanding what types of gases it is possible to see with OGI technology will help in choosing a camera and becoming an expert in its operation.
What is optical gas imaging?
Optical gas imaging uses a spectrally filtered thermal camera to visualize otherwise invisible gas leaks. It works by measuring the infrared radiation passing through a volume of gas. Each gas has its own spectral absorption characteristics, and many gas compounds will absorb some infrared energy, but only within a certain narrow range of wavelengths.
Within this very narrow range, aimed at a specific gas, OGI cameras can visualize where there is a column of gas, which usually looks like a cloud of smoke, blocking the energy from reaching the IR detector. This cloud is where the gas absorbs the energy at that wavelength.
What types of gases can be visualized?
Because OGI cameras image the gas as a lack of infrared energy, they can only image gases that absorb infrared radiation in the filtered bandpass: gases that do not absorb IR in the filtered bandpass will not be visible. For example, noble gases such as helium, oxygen and nitrogen cannot be imaged directly.
However, hundreds of other industrial gases absorb infrared energy and can be imaged with OGI. Most hydrocarbons (benzene, butane and methane, for example) absorb radiation near the 3.3 μm (micrometer) wavelength and can be imaged with a camera such as the FLIR Gx620. Sulfur hexafluoride (SF6) absorbs energy near 10.6 μm and can be detected with a camera such as the FLIR G306.
Even if a camera can image a specific gas, it will not image another gas that has drastically different infrared absorption properties. That is why FLIR has a range of OGI cameras for detecting different gases. You can use this chart to determine which FLIR G-Series camera model is best suited for your application.
Download the complete list of gases and the G-series camera models that can detect them.
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