Industrial gas leaks not only represent millions in economic losses, but also severe risks to workplace safety and a direct environmental impact. However, the vast majority of these chemical compounds are completely invisible to the human eye. This is where FLIR’s OGI (Optical Gas Imaging) technology comes in, an advanced solution that allows you to “see” these gas clouds in real time. But can a single thermal camera detect any type of gas? The short answer is no. It all depends on the gas’s physics and wavelength.
The Physics of Detection: How does a thermal camera “see” gas?
For a FLIR OGI series camera to detect a gas, the gas must absorb infrared radiation in a specific region of the electromagnetic spectrum. The camera works by filtering the light to allow only the exact wavelength where the gas interacts to pass through. When gas comes between the thermal background and the camera, it absorbs that energy, appearing on the screen as a dark (or bright, depending on the settings and the high-sensitivity mode, HSM) “cloud of smoke.”
Pure noble or atmospheric gases such as oxygen (O₂), nitrogen (N₂), or hydrogen (H₂) do not absorb infrared radiation in these bands, so they cannot be detected by optical thermography. However, hundreds of hydrocarbons and industrial compounds do.
Classification of Gases by Absorption Bands (FLIR Models)
FLIR has developed a specific range of cameras (historically known as the GF series and evolved into the current G series) divided according to the wavelength at which they operate:
1. Light hydrocarbons, Methane and VOCs (Short/Medium Wave Infrared – MWIR)
Most hydrocarbons (such as propane, butane, hexane, and methane) strongly absorb radiation in the 3.2 to 3.5 micron (μm) band. This is the critical zone for the oil, natural gas and petrochemical industry.
Reference FLIR cameras: FLIR Gx320, G620, Gx620 (previous GF320 / GFx320 intrinsically safe).
2. Sulfur Hexafluoride (SF₆) and Ammonia (Long Wave Infrared – LWIR)
SF₆ is a massive greenhouse gas used as an insulator in high-voltage electrical substations. It absorbs radiation near 10.3 to 10.8 μm, a completely different band than natural gas. Ammonia (NH₃), very common in refrigeration and fertilizer plants, is also detected in this range.
Reference FLIR cameras: FLIR G306 (previously GF30)
3. Carbon Dioxide (CO₂) and Carbon Monoxide (CO)
CO₂ (critical for carbon capture and industrial processes) has a very narrow absorption signature between 4.2 and 4.4 μm, while carbon monoxide (CO), a highly toxic gas in the steel and manufacturing industry, is visualized between 4.5 and 4.7 μm.
Reference FLIR cameras: FLIR G343 (for CO₂) and FLIR G346 (for CO).
The added value of bcb: Integration and Software Beyond the Camera
Having the right camera is only half the solution. At bcb, we go beyond manual inspection by developing bcbGasScan, our advanced, custom-designed software specifically for the continuous and automated processing of optical gas images (OGI).
Thanks to the power of bcbGasScan, our integrated systems transform a thermal camera into an intelligent industrial safety node: Onboard and remote quantification: Through advanced algorithms, bcbGasScannot only makes the gas cloud visible but also accurately estimates the mass flow rate (g/hr) or its concentration level (ppm·m). Fixed continuous monitoring systems: The software enables the integration of automated, fixed OGI cameras operating 24/7. In the event of any anomaly, it reports critical and immediate alarms to the plant’s SCADA system, completely eliminating the need for periodic human inspections in high-risk explosive atmosphere (ATEX) zones.