The Expert Speaks: Tips for making the most of optical gas imaging
What critical techniques are you missing that could make methane leak mitigation faster and easier?
By Craig O'Neill
OGI is the fastest, most efficient way to track gas leaks to their source. But it's important to understand how to use the technology if you want to get the most out of it. A crucial point about OGI: it saves money, not only through efficiency and the reduction of lost product, but more importantly, by improving the safety of company personnel and assets.
OGI as a technology is advanced enough that having the right training and a few helpful tips from an expert can make a world of difference. So here are ten tips I think will help you become more efficient in the field.
1.
Have the right camera for your application.
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, an OGI camera filtered for volatile organic compounds (VOCs) and hydrocarbons will not see sulfur hexafluoride (SF6); a carbon monoxide (CO) camera will not see refrigerants.
Additional questions to consider: what level of accuracy do you need, and what types of data do you need to collect? Some optical gas imaging cameras use a highly-sensitive detector with a sterling microcooler in order to see the smallest leaks. FLIR's latest line of cooled cameras also offer quantitative measurement—called QOGI—so you can record the size of a natural gas leak.
For larger leaks, or situations where you don't need the highest sensitivity, you could prefer an uncooled OGI camera. These cameras still detect gases accurately but at a lower cost.
SF6 insulator leak
Methane leak from a pressure gauge
OGI image of a tank farm with active venting. OGI cameras are filtered to specific wavelengths that make gases visible against a backdrop such as the sky. The camera can also detect temperatures, which is why the tank fill-line is visible in the image.
2.
Take the environment into account.
The most important thing to remember when looking for gas leaks is to ensure there's enough contrast between the background and the leak. Otherwise, it will be difficult for the camera to visualize the gas leak and pinpoint its source.
Active gas detection technology, (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.
An increased temperature difference—or Delta T (ΔT)—helps detectability, so working with a camera that can easily provide thermal analysis, including ΔT, makes optical gas imaging easier.
Below, the first image shows a tank with large areas of Delta T (ΔT) challenges. If wind wasn't blowing the gas away from the vent line, it would be undetectable. The second image from a FLIR Gx320 camera shows a ΔT check, in which specific pixels that do not have sufficient ΔT are highlighted and the operator can ensure proper inspection of all components.
3.
OGI can be both qualitative and quantitative.
Due to the environmental changes and the background energy differential and variations, an OGI camera alone cannot determine the specific type or amount of gas escaping through a leak; but, with specially engineered software, it can quantify the emission. Some technologies require additional hardware to provide quantification capabilities. But the FLIR G-Series hydrocarbon cameras allow quantification in-camera for immediate, in-field measurements of mass leak rates (lb/h or g/h), volumetric leak rates (cc/min or l/min) or concentration (ppm x m) for most hydrocarbons.
The FLIR G-Series camera, to the right, displays not only a thermal image of the methane flare but also an accurate measurement of the leak rate, known as in-camera quantitative OGI (QOGI).
4.
Make full use of the camera.
It's important to learn how each feature of the OGI camera works—such as integrated GPS, LCD touchscreen or image enhancements—and use them to your advantage. Small concentrations of gases can be difficult to see, even with an OGI camera. High Sensitivity Mode (HSM) enhances the image, so even small concentrations of gas are visible. Notation features, such as GPS tagging and logging, can be critical to ensuring crews make the repairs on the correct asset or even assist in complying with local regulations. With a LCD touchscreen integrated into the camera, utilizing key features, such as data input or 1-touch level/ span, for streamlined inspections, is key.
From natural gas extraction to petrochemical operations and power generation, companies have saved more than $10 million annually in lost product by including FLIR optical gas imaging in their leak detection and repair (LDAR) programs.
5.
Get the temperature measurements right.
Many OGI cameras are temperature- calibrated, making them dual-use systems. They are suitable for industrial maintenance inspections because they can measure and record temperatures across the scene and save the data to a JPEG or video. You can use these cameras to detect hot spots or electrical problems in high and low-voltage mechanical and electrical installations, or to look for insulation failures in pipework, ovens, and much more.
The thermographic function on your OGI camera can also help you improve the visual contrast between a gas cloud and the background scene, commonly referred to as delta-T. Unlike with other thermographic applications, your object of detection (gas) has no visual representation. You can only see the cloud by creating a slight radiant contrast between the cloud ambient temperature near the emission source and the background. The key to making the emission visible is utilizing a camera that simplifies the temperature difference (∆T) between the cloud and the background.
6.
Use the camera's advantages to keep safe.
Gas imaging cameras are a quick, non-contact method for detecting leaks in hazardous or hard-to-reach areas, often known as difficult- to-monitor (DTM) sources. They are sensitive enough to detect small leaks from several meters away and large leaks from hundreds of meters away. Many OGI cameras offer visual enhancements such as HSM or 1-touch level/ span, which can improve detection of leaks that are small or low in concentration. With simple field interchangeable lenses for the camera, an operator can easily adjust their inspection perspective for a variety of use cases.
Because OGI allows you to detect gas emissions from a safe distance, you should use it to your advantage. Beginning outside of the main work area, take an initial scan of the area to determine if there are any large gas leaks visible.
Then, you can move in closer or change your lens for more specific scans. Be sure to wear appropriate safety gear, and store and transport your OGI camera in its provided case. Also, keeping up with camera maintenance will ensure it doesn’t become its own safety hazard.
7.
Understand your hazardous classification ratings.
Many companies or industries operate in hazardous environments and have unique requirements for gas detection equipment.
Permits are often required when using equipment in Zone 2 (Class 1; Division 2) environments, unless it is certified compliant in those areas. Having an OGI camera that detects hydrocarbons and meets these Zone 2 (Class 1; Division 2) hazardous classification certifications will allow an operator to use the camera without a hot work permit.
Additionally, a high-resolution OGI camera may allow you to see significant and dangerous leaks from a safe area that is not designated as hazardous, even outside of the facility perimeter. For the most flexible solution for ensuring safety, consider a camera that is both high-resolution and hazardous locations certified.
8.
Keep track of your ROI.
In many cases, an OGI camera can pay for itself on the very first day. Surveys performed with an OGI camera are generally nine-times faster than traditional leak detection technology, and they can help you detect leaks you might miss with a sniffer.
OGI is also a non-contact method that can be performed during normal operations; therefore, companies don’t lose revenue to shutdowns. Plus, by catching leaks early and making repairs quickly, companies can both avoid fines and improve the environment by meeting corporate ESG metrics. The thermographic function on your OGI camera can also help you improve the visual contrast between a gas cloud and the background scene, commonly referred to as delta-T. Unlike with other thermographic applications, your object of detection (gas) has no visual representation. You can only see the cloud by creating a slight radiant contrast between the cloud ambient temperature near the emission source and the background. The key to making the emission visible is utilizing a camera that simplifies the temperature difference (∆T) between the cloud and the background.
9.
Communication is key to documentation.
Many LDAR professionals need to document their findings for internal record-keeping requirements, to streamline the repair process or to comply with regulations. Having a camera that can easily and wirelessly communicate with third party LDAR software, seamlessly store files with integrated cloud storage, or even guide an operator through a route-based detection path, is ideal. Having the right tool with the integrated technology to streamline the inspection process will put your company ahead.
10.
Get the right training.
Learning how to most effectively use your OGI camera will ensure you get the most out of your investment. You might consider a training course by ISO certified organizations such as the Infrared Training Center.
The ITC offers low-cost online training called “OGI Fundamentals” as well as a three-day Optical Gas Imaging certification class covering fundamental concepts of OGI, parameters that can affect detection, procedures for performing surveys, common mistakes/best practices, how environmental conditions affect gas leak detection, and more. Students completing the training course will receive an OGI Infrared Thermography Certification, a wallet ID card, and the knowledge to be a successful OGI thermographer.
