Method 21 vs OGI Fugitive Emissions in Saudi Arabia

Saudi Carbon Monitoring coordinates Method 21 vs OGI fugitive emissions surveys for facilities across Saudi Arabia, helping operators choose how leaks are detected, screened and documented. We scope and coordinate the survey, and licensed or qualified parties carry out the field work with the method selected for the governing requirement, target gas, site conditions and hazardous-area needs.

You receive a written proposal setting out the survey scope, method, responsibilities, lead time and price. Request a quotation

Method 21 and optical gas imaging are both used in fugitive-emissions work, but they observe leaks differently. Method 21 places a portable instrument probe near a potential leak interface and records a VOC screening concentration. OGI uses an infrared camera to visualise gases it can detect under the actual scene conditions. Choosing between them starts from the governing requirement, and neither method replaces the permit or regulatory decision that applies to your facility.

Method 21 in practical terms

US EPA Method 21 specifies instrument performance and procedural requirements for determining VOC leaks. Work includes calibration and response checks, appropriate probe movement and placement, background consideration and component-level recording. A leak threshold is defined by the applicable rule or programme, not by the method alone.

The result is a screening concentration, often in parts per million. It is not automatically a mass leak rate. Quantification may use an accepted correlation or separate method.

OGI in practical terms

An OGI camera detects infrared contrast from suitable gases against the background. Performance depends on gas properties, release rate and temperature, distance, wind, scene background, camera settings and operator technique. OGI can scan equipment and show maintenance personnel where a release appears.

A non-visible plume does not mean zero emissions. The gas may be outside the camera response, the rate below detection for conditions, or the scene may have poor contrast. Quantification needs a validated approach if required.

Method 21 vs OGI fugitive emissions: coverage, speed and documentation

OGI can support rapid scanning, but documentation and access still take time. Method 21 can provide component readings but requires close access and systematic probing. Survey design should define component populations, route, environmental limits, safety and excluded equipment.

Both methods need controlled instrument records, operator competence and component identity. OGI files should link to tags and context; Method 21 readings should link to calibration, background and exact interface.

Using both methods

A programme may use OGI for broad screening and Method 21 for defined measurements, or the reverse, if the requirement allows. The workflow should state which method classifies a leak, which verifies repair and how conflicts are resolved.

The Method 21 and OGI coordination service prepares that field scope. The wider LDAR programme governs repair, recheck and exceptions.

Avoid common claims

Do not say OGI sees every gas, that Method 21 directly measures kilograms per hour, or that either method alone proves an annual inventory. Do not use “zero emissions” for a non-detect. State the threshold, conditions and intended use.

Example combined survey

A facility may use OGI to scan a process unit and rapidly locate visible releases, then apply Method 21 where the programme requires a screening concentration. The OGI file and Method 21 reading should link to the same component and operating status. Maintenance receives one controlled finding, and the recheck follows the programme-defined method.

If the facility also wants a mass estimate, that becomes another technical step. A specialist selects an accepted correlation, enclosure, high-flow or other method and states uncertainty. The GHG practitioner then decides how coverage and duration enter the inventory. A video alone should not be translated into tonnes.

Field readiness checklist

Confirm the following before mobilising:

• component register and route
• target gases and expected conditions
• hazardous-area requirements, permits, access and weather limits
• instrument checks and calibration gases
• file naming and repair interface
• how newly found and inaccessible components are recorded

Ask the bidder to state whether the result is detection, concentration screening or quantification. This checklist makes different proposals comparable and prevents equipment marketing from replacing method design.

Reporting language that stays accurate

Use “detected,” “not detected under stated conditions,” “screening concentration” and “quantified by the stated method” deliberately. Do not say “zero leak,” “camera-certified” or “measured mass rate” unless the evidence supports that exact statement. A clear report describes coverage, environmental conditions, excluded components, instrument checks and required follow-up.

For management summaries, retain links to component-level data. A count by unit is useful, but it should not hide un-surveyed areas or failed rechecks. Accurate language protects both maintenance decisions and later inventory use.

Next step

For Method 21 vs OGI fugitive emissions surveys in Saudi Arabia, send us your facility type, target gases and governing requirement. Request a quotation