NDIR Gas Detection

NDIR gas detection uses infrared absorption to identify and measure target gas concentration. It directs IR light through a sample gas volume. The detector then measures the reduction in transmitted intensity at the gas’s characteristic absorption wavelength. This principle delivers continuous, non-consumptive, selective gas detection. Furthermore, it avoids the poisoning and drift limitations of catalytic bead and electrochemical sensors.

Each gas molecule absorbs IR radiation at specific wavelengths. CO2 absorbs at 4.26 µm. CO absorbs at 4.67 µm. Methane absorbs at 3.3 µm. N2O absorbs at 4.5 µm. Bandpass filters isolate each target gas’s absorption wavelength at the photodetector. This rejects signals from other atmospheric components. Additionally, dual-wavelength reference channels add a second detector at a non-absorbing wavelength. The ratio between sample and reference channels compensates for source aging, temperature drift, and optical contamination — maintaining calibration accuracy over multi-year service intervals.

Fixed-point NDIR detectors mount in process areas, compressor rooms, and gas turbine enclosures. They output 4–20mA analog signals and Modbus RTU communication for PLC and SCADA integration. Open-path NDIR detectors project a beam across 5 to 200 meters. They detect diffuse releases that point detectors miss between sensor positions. Moreover, portable NDIR analyzers handle spot checks, confined space pre-entry surveys, and leak investigation without fixed infrastructure.

Sensor service life on NDIR detectors reaches 5 to 10 years. This is significantly longer than catalytic bead sensors. As a result, maintenance costs and calibration visit frequency drop considerably across large detector installations.

These systems serve Pakistan’s SSGC and SNGPL gas networks, OGDCL processing facilities in Sindh and Balochistan, WAPDA gas turbine plants, fertilizer manufacturers in Multan and Lahore, and pharmaceutical cleanroom monitoring programs.

Tactical Supply Pakistan supplies NDIR gas detection systems for industrial safety monitoring, pipeline leak detection, and environmental compliance procurement across Pakistan.