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Optical Gas Imaging (OGI) Vs. Method 21 (Gas Sniffers)


2 mins


Dr. Ram Hashmonay

published published

December 14, 2021


OGI Knowledge BaseOptical Gas Imaging (OGI)

Optical Gas Imaging Vs. Method 21

Optical Gas Imaging (OGI) technology has proven to be a handy tool for detecting and visualizing small gas leaks and more substantial fugitive emissions in petroleum refineries and other Oil & Gas facilities.

OGI technology is currently the preferred technology for detecting leaks and emissions of hydrocarbon compounds worldwide. US state and federal regulatory frameworks are transitioning from conventional methods, e.g., gas sniffers, to visualizing and detecting leaks using OGI cameras for Leak Detection and Repair (LDAR) applications1. The US Environmental Protection Agency (EPA) federal regulation, ‘Quad Oa’ (OOOOa)2, approved in 2016, states that this is the Best System of Emission Reduction (BSER).

The table below, sourced from the current US EPA OGI protocol3, shows that the LDAR survey-based OGI camera is more efficient than the conventional Method 21 point monitor (gas sniffers) LDAR survey.

Determination of Volatile Organic Compound and Greenhouse Gas Leaks Using Optical Gas Imaging

The OGI-based LDAR surveyor may screen for leaks in up to 20 components with only 30 seconds dwelling time when covering 0.5m2 of monitoring area (about 2 meters distance for the EyeCGas 2.0). In the conventional LDAR survey, the surveyor must dwell on each component individually from zero distance for a similar dwelling time, i.e., 30 seconds. This data demonstrates a 20 fold increase in the efficiency of the OGI LDAR and the ability to survey hard-to-reach components.

Without the visualization of the exact point of gas release with the conventional approach, the repair might be applied to the wrong component, possibly damaging a non-leaking part and not repairing the leaking component.

Opgal’s (OGI) Camera, the EyeCGas 2.0, is the world’s most sensitive handheld Optical Gas Imaging camera. It quickly identifies fugitive emissions for Methane and over 400 hydrocarbon and VOC gases. EyeCGas 2.0 is Intrinsically Safe and complies with the EPA’s “Quad Oa” (OOOOa) regulations.


  1. US Environmental Protection Agency. Stationary Sources of Air Pollution, September 22, 2020,
  2. Environmental Protection Agency. Oil and Natural Gas Sector: Emission Standards for New, Reconstructed, and Modified Sources [PDF File]. Federal Register / Vol. 81, No. 107 / Friday, June 3, 2016 / Rules and Regulations,
  3. Environmental Protection Agency. 40 CFR Part 60 Appendix K (Proposal) – Determination of Volatile Organic Compound and Greenhouse Gas Leaks Using Optical Gas Imaging.