Dual Gas Infrared Sensor

A Dual Gas Infrared Sensor is an optical detection device that simultaneously measures the concentration of two distinct gas species within a single sensor housing by exploiting the principle that different gas molecules absorb infrared radiation at characteristic wavelengths specific to their molecular structure. By incorporating two narrow-band optical filters — each centered on the absorption wavelength of a target gas — and a matched reference channel within one detector assembly, the sensor delivers independent concentration readings for both target gases from a single measurement cycle without requiring two separate instruments.

The sensor operates on the non-dispersive infrared (NDIR) detection principle. An infrared light source — typically a pulsed broadband emitter or LED — illuminates a gas sample cell through which the measured atmosphere passes. At the far end of the sample cell, a dual-channel detector assembly with two active measurement filters and one or two reference filters measures transmitted infrared intensity at each wavelength. The reduction in transmitted intensity at each measurement wavelength relative to the reference channel corresponds directly to the concentration of the absorbing gas at that wavelength, calculated through the Beer-Lambert law relationship.

Common dual gas NDIR sensor configurations target gas pairs including CO₂ and CH₄ for greenhouse gas and biogas monitoring, CO and CO₂ for combustion analysis, CO₂ and water vapor for indoor air quality assessment, and hydrocarbon pairs for petrochemical process monitoring. Measurement ranges vary by application — CO₂ channels typically cover 0 to 5,000 ppm for indoor air quality and 0 to 100 percent for industrial process monitoring, while methane channels span 0 to 100 percent of lower explosive limit (LEL) for safety monitoring applications.

Response times on current dual gas infrared sensors reach T90 values — the time to reach 90 percent of final reading — of 15 to 30 seconds, with operating temperature ranges from -20°C to +60°C and humidity tolerance up to 95 percent non-condensing on sealed sensor designs.

In Pakistan, dual gas infrared sensors are installed in industrial facilities handling combustible or toxic gases, building management systems monitoring indoor CO₂ and air quality, oil and gas processing plants, waste treatment facilities, and laboratory analytical instruments.

Tactical Supply Pakistan supplies dual gas infrared sensors for industrial safety, environmental monitoring, and analytical instrument integration across Pakistan.