Our Guide to Optical Gas Imaging

This month we’re focusing on optical gas thermal imaging, and some of the technology that’s available to help you conduct a gas imaging survey correctly & safely.

So, what exactly is optical gas imaging? Optical gas imaging (or simply OGI) is designed to allow you to see inaccurate gas emissions. Gas leaks can have a huge financial impact on an organisation. Having a gas leak could result in regulatory fines and mean significant downtime, so it’s important to quickly and easily detect such leaks so they can be fixed. FLIR OGI cameras allow you to see a visual representation of any leaks.


OGI technology

Using OGI technology is very similar to looking through a normal video camera, but the user sees a plume of gas (resembling smoke) emanating from any leaks etc. Without an OGI camera, these gases would effectively be totally invisible to the naked eye. For you to see a plume of gas, OGI cameras use a unique spectral (wavelength-dependent) filtering method that enables them to detect specific gas compounds.

FLIR OGI - Thermal Imaging

If a FLIR OGI camera is used at a scene without any gas leaks, objects in the field of view will emit and reflect infrared radiation through the lens and filter of the camera. If a gas cloud exists between the objects and the camera (and that gas absorbs radiation in the band pass range of the filter), the amount of radiation passing through the cloud to the detector will be reduced. Therefore, to see the cloud in relation to the background, there must be a radiant contrast between the cloud and the background.

In summary, the keys to making a gas cloud visible to your OGI camera are:

1)     The gas must absorb infrared radiation in the waveband the camera sees

2)     The gas cloud must have radiant contrast with the background,

3)     The apparent temperature of the cloud must be different than the background.

FLIR systems have recently released the new GF620 OGI camera, and we have the scoop! This is their first high-resolution OGI camera, and is a “cooled” OGI solution giving you access to considerable advantages of a cooled OGI camera. Without cooled filtering, you lose thermal sensitivity due to limiting the radiation that reaches the camera’s detector. Perhaps most importantly, only one cooled camera would usually be required to detect and visualise a wide variety of gases. In the case of the FLIR GF620, detectable gases include methane, propane, sulphur dioxide and nitrous oxide.

Watch a short video about the FLIR GF620 and its capabilities here:

The GF620 provides users with a high-resolution, 640 × 480 detector that visualises gas leaks better than ever before. This is a four-fold increase in pixels compared with previous models, enabling you to find leaks up to nine times faster than with traditional “gas sniffer” methods. Ultimately, the new GF620 aims to help users to detect small leaks quickly and safely, meet compliance requirements, and save both time and money. It’s built with a rugged silicone exterior and drop-tested magnesium frame, designed to easily withstand tough work environments. It’s also been made with the user’s comfort in mind, especially when conducting long surveys (perhaps even all day), thanks to the tilting eyepiece, adjustable LCD screen, and rotating handgrip that you might usually see on a normal video recorder.

When it comes to detecting gas, the GF620 features noise-reduction filtering and a High Sensitivity Mode (HSM), which accentuates plume movement to make even the smallest leaks easier to see. The GF620 is also the first FLIR camera to offer a Quantification Mode (Q-Mode), which allows for faster post-processing of data with the QL320 software. This allows you to measure and confirm the size of a leak when surveying components that are hard to measure or particularly difficult to access. Built-in GPS adds location data to each image and video, in turn streamlining your work and further aiding in regulatory compliance.

Away from OGI, the GF620 also allows you to check electrical and mechanical systems for signs of failure. It’s calibrated to measure temperatures up to 350°C (662°F) with ±1°C accuracy, so you can check your equipment for hot spots before they become a bigger problem and avoid downtime from major repairs.

The FLIR GF620 is available on our website now; please contact us if you’d like any further information or to request a quotation for our thermal imaging services. We’ll also be back next month with news of another new FLIR camera release, so watch this space!