Optical Gas Imaging – Part 2: Effectiveness of Fugitive Emission Detection Technologies

Optical Gas Imaging

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Gas Detection Technologies Landscape

Over the past decade, several new technologies have been introduced to detect and measure natural gas leakage. There are optical/infrared (IR), flame ionization detectors (FID), Method 21 gas sniffers (older), and others. Devices utilizing these technologies can be fixed-position, portable/or hand-held, or drone-mounted. Some are to be used remotely, others in closed area applications.

Needless to say, each technology has its limitations and selling points.

As we mentioned in the previous post, in the USA, optical gas imaging detectors are a recommended method of gas emissions detection.

In a 2003 4-plant pilot study by EPA and the Gas Technology Institute (GTI) found that by using Optical Gas Imaging (OGI) technology, facilities could reduce methane emissions by up to 96% and save up to $164,000 per plant annually. In 2015 the CONCAWE review, based on four large field trials for detecting non-methane volatile organic compounds in LDAR programs (OGI and Hand-held Leak Detectors like gas sniffers), found that OGI technology is faster and, while both methods can detect fugitive emissions, OGI can better find leaks.

It’s no surprise then, that the EPA appointed OGI as their monitoring and enforcement technology of choice. Primarily because it is an effective gas detection technology that helps to quickly and safely expose gas leaks, which would take longer time to do using some other tool.

To give an example, let’s quickly compare Optical Gas Imaging (OGI) with some traditional technologies like Flame Ionization Detector (FID):

While being relatively inexpensive, FIDs are much less effective. They cannot detect inorganic substances that some highly oxygenated or functionalized species like optical/infrared gas detection technologies can. This makes it an ineffective tool in a big number of applications.

To quickly compare OGI with traditional Method 21 gas sniffer technology:

“Sniffers” are devices that measure the concentration of a certain gas in one single location and generate a concentration reading in parts per million (PPM). Sniffers, however, have a range of limitations. Most importantly the operator has to be near the gas leak location, which compromises the operator’s safety. Plus, as it is dangerous to use a gas sniffer on energized equipment, it must be de-energized to inspect the areas with suspected leaking which translates to downtime.

Whereas gas sniffers just give us a PPM number telling “there is a leak around somewhere here,” an optical gas imaging camera allows to pinpoint an exact source of a gas leakage anywhere within the camera’s field of view.

Besides being safer and more effective, optical gas imaging cameras have the following advantages over gas sniffers:

  • They can scan a broader area much faster
  • Allow working from a safe distance
  • Scan difficult to reach areas that are impossible to reach with a “sniffer”
  • Can be used as a predictive tool in proactive temperature monitoring: detect leaks in unexpected locations
  • Many other functions unavailable in “sniffers”

As you can see, technology has advanced a lot but let’s take a closer look at OGI technology to learn more of its benefits and why it’s so widely used.

How OGI works

An optical gas imaging camera is an infrared camera that uses advanced thermal imaging technology to “see” invisible gases. It outputs a picture on a screen and displays a leak as a plume of vapor.

The gas visualization of an OGI camera is based on the principle of infrared absorption. Gases absorb electromagnetic radiation in certain parts of the spectrum and the camera can detect that. When the infrared laser beam is transmitted from the camera, some of the laser is reflected back and converted to an electrical signal needed to determine gas concentration.

An OGI camera that can visualize Volatile Organic Compounds (VOC) is a very safe tool for tracing dangerous gas leaks. It can detect small leaks from several meters away and big leaks from hundreds of meters away. It is a quick, non-contact measuring instrument (operated remotely).

Some cameras used in the detection of methane leaks can visualize methane flows well below the EPA required 60 grams per hour sensitivity level. This makes OGI a highly effective technology. That’s why it has been adopted in many industries as the method of choice.

Main benefits to using OGI for gas leak detection

This sensing technology has recently become a field-proven solution in the gas detection and monitoring industry replacing traditional methods, like Method 21 gas sniffer technology.

This is because OGI is best technology for identifying problems and early signs of hidden mechanical faults from a distance, long before they become dangerous, gas reaches hazardous concentrations, or problems become very expensive to fix. This improves efficiency and the safety of the operators, and translates to big savings in time and personnel.

They are also invaluable for decreasing the environmental impact of the industry by helping to cut the volume of fugitive gasses like methane, VOCs, and other GHGs. OGI cameras are already saving the industry millions of dollars annually in lost product as well as in fines for non-compliance with regulatory limits for leaked GHGs set by government bodies.

OGIs have many other advantages over the traditional leak detectors:

  • Simple and user-friendly: real-time visualization allows to visually see gas
  • Have a “camcorder:” recording both visual light video and thermal video footage
  • Informative: exact leak localization
  • Proactive: can help predict or identify equipment malfunction before it becomes critical
  • Reliable: no calibration needed
  • Require no fuel for operation: no need for hydrogen or hydrogen/nitrogen gas
  • Versatile: detect many gas types, portable or fixed application
  • Fast return of investment: low total cost of operation and maintenance

Due to such a big number of improvements to gas detection technology, it’s no wonder that Optical Gas Imaging has quickly found its place in the forefront of leak detection technology.


Over the recent years, remote optical/laser-based cameras have proven to be most reliable replacements solution and are replacing traditional flame ionization and Method 21 instruments.

Companies utilizing this technology as a regular part of their monitoring strategy massively reduce levels of fugitive gas leaks, save money, lives and the environment by avoiding major problems before they develop, while meeting compliance regulations and environmental standards set forth by regulatory agencies around the world.

In the next installment in this series, we will take a look at specific OGI products that are available on the market today.