What Types of Gases Can You See With an OGI Camera?

FLIR gas detection cameras can help you "see" hundreds of invisible gases quickly and safely, but not every type of gas can be visualized with optical gas imaging (OGI). Understanding what types of gases it's possible to see with OGI will help with 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, targeted to a specific gas, OGI cameras can visualize where a gas plume exists, which typically looks like a smoke cloud, by blocking the energy from reaching the IR detector. This cloud is where the energy in that wavelength is being absorbed by the gas.

What Types of Gases Can Be Visualized?

Because OGI cameras visualize gas as a lack of infrared energy, they can only image gases that absorb infrared radiation in the filtered bandpass: gases that don’t absorb IR in the filtered bandpass won’t be visible. For instance, noble gases such as helium, oxygen, and nitrogen cannot be directly imaged. 

Hundreds of other industrial gases, however, do absorb infrared energy and can be visualized with OGI. Most hydrocarbons—benzene, butane, and methane for example—absorb radiation near the wavelength of 3.3 μm (micrometers) and can be visualized with a camera like the FLIR G-Series for hydrocarbons. Sulfur hexafluoride (SF₆) absorbs energy near 10.6 μm and can be detected with a camera like the FLIR G306. 

Even if one camera can visualize a specific gas, it will not visualize another gas that has drastically different infrared absorption properties. This is why FLIR has a portfolio of OGI cameras for detection of a variety of gases. You can use this chart to determine which GF model FLIR cameras are best suited to your application.

Learn more about FLIR OGI solutions: flir.com/ogi