Ten tips to get the most out of optical gas imaging

Optical gas imaging cameras are powerful tools for detecting fugitive emissions that are not visible to the eye.

Optical gas imaging (OGI) cameras use spectral wavelength filtering and sterling cooler cold filtering technology to visualise the infrared absorption of VOC/hydrocarbon, sulfur hexafluoride (SF₆₎, refrigerants, carbon monoxide and other gases whose spectral absorption matches the response of the camera.

By using OGI technology, the industry is able to incorporate a ‘Smart LDAR’ (leak detection and repair) program that allows operators to safely and efficiently visualise gas leaks. OGI has allowed the industry to reduce industrial emissions and operators to conform to future regulations. In addition, OGI saves money, as part of a much more efficient process, but most importantly, it improves the safety of their assets and their personnel.

To get the most out of your OGI equipment, you should consider the following 10 tips.

1. Understand the application and needs

Different applications require different cameras. In other words: one camera may not see all the gases, so you need to understand which type of gas you are dealing with. For example, a VOC/hydrocarbon OGI camera will not see SF₆ and a CO camera will not see refrigerants.

Figure 1: SF₆ leak from a high voltage insulator.

2. Take into account the environmental conditions

The success of passive optical gas imaging depends on environmental conditions. The greater the background energy differential, the easier the camera will be able to visualise the gas leak and pinpoint its source. Active optical gas imaging (ie, using a laser-based backscattering technique) relies on a reflective surface in the background. This presents a significant challenge when you are looking at components high up and pointing the camera at the sky. Also, rain and strong winds need to be taken into account. Rain can make detection very difficult, but wind can actually help visualise the gas because it makes the gas move.

3. Keep in mind that optical gas imaging is qualitative, not quantitative

Due to the environmental variants, background energy differential and variations, an OGI camera will not be able to tell which amount of gas is leaking or what gas it is. An OGI camera will, however, pinpoint the source of the leak in the most efficient and effective way.

4. Combine an optical gas imaging camera with a sniffer probe

Use an OGI camera to visualise the leak and trace its source. Then, use a sniffer probe — a toxic vapour analyser (TVA) or organic vapour analyser (OVA) — to quantify the leak. Combining an OGI camera with a sniffer probe is referred to as Smart LDAR.

5. Use all the features and functions on your OGI camera

Certain OGI cameras are dual-use systems. They can also be used for industrial maintenance inspections, including high- and low-voltage electrical installations, mechanical installations, pipework and insulation, ovens and many more. The thermographic function on your OGI camera will also help you determine the background temperature or energy the gas is absorbing. Unlike with other thermographic applications, your object of detection (gas) has no visual representation and it is moving constantly. Therefore, a continuous focus is most important and so is the thermographic capability to determine the temperature range settings. An OGI camera also allows you to record a movie to capture the movement and pinpoint the leak. It is always advised to take a visual image.

Figure 2: A leaking pressure gauge.

6. Keep it safe

A gas imaging camera is a quick, non-contact measuring instrument that can also be used in hard-to-access locations. It can detect small leaks from several metres away and big leaks from hundreds of metres away. It can even show leaks on moving transport vehicles, thereby greatly improving the safety of both the inspector and the plant. Thanks to their great performance, sensitivity and, with some cameras, also a high sensitivity mode (HSM), you can scan for leaks from a safe zone or even from a greater distance, compared to traditional gas detection methods.

7. Consider future industrial emissions regulations

Fugitive gas emissions contribute to global warming and pose deadly risks to both workers and people living close to these facilities. Optical gas imaging cameras detect dozens of volatile organic compounds, including the greenhouse gas SF₆, efficiently contributing to a better environment. Optical gas imaging cameras also allow you to comply with new industrial emissions regulations and procedures as set by the new EU Industrial Emissions Directive (IED) and by some EPA regulations in the United States.

8. Keep track of your return on investment

In many cases, the cost of the camera is paid for within its very first survey and in some cases with the finding of the very first leak.

9. Work with permits

OGI cameras in general are not Zone 1 ATEX certified. Therefore, you will need to apply for a ‘hot work permit’ or use it under a ‘permit to work scheme’. Remember, you can see significant and dangerous leaks with the right camera from a safe zone, even outside of the facility’s perimeter.

10. Follow training

Learn from experienced and qualified OGI users to get the most out of your camera. You might follow a training course by quality organisations such as the Infrared Training Center (www.infraredtraining.com).