NDIR Sensor

NDIR sensors measure gas concentration through infrared light absorption. They project IR light from a broadband source through a sample gas volume inside a measurement cell. A bandpass filter isolates the target gas’s characteristic absorption wavelength at the photodetector. The detector measures intensity reduction at this wavelength. The sensor then converts this attenuation to a concentration reading in ppm or volume percent. Furthermore, this principle is continuous, non-consumptive, and highly selective — avoiding the poisoning, drift, and cross-sensitivity limitations of catalytic bead and electrochemical sensor technologies.

Each gas absorbs IR radiation at a distinct molecular wavelength. CO2 absorbs at 4.26 µm. CO absorbs at 4.67 µm. Methane absorbs at 3.3 µm. N2O absorbs at 4.5 µm. SO2 absorbs at 7.3 µm. Dual-wavelength reference designs add a second detector at a non-absorbing wavelength. The ratio between sample and reference signals cancels source aging, temperature variation, and optical fouling. As a result, NDIR sensors maintain calibration accuracy across 5 to 10 year service intervals without frequent recalibration.

OEM NDIR modules integrate into fixed detector heads, portable analyzers, HVAC controllers, capnography instruments, and process analyzers. Output interfaces include 4–20mA analog, Modbus RTU, HART, RS-232, and I2C digital protocols. Compact low-power modules such as the Senseair S8 consume under 35mW — suitable for battery-powered IoT instruments and demand-controlled ventilation systems. Additionally, industrial NDIR sensor assemblies in ATEX and IECEx Zone 1 certified housings meet hazardous area installation requirements across Pakistan’s oil and gas processing plants and petrochemical facilities.

Open-path NDIR sensor pairs project IR beams across 5 to 200 meters. They detect diffuse gas cloud releases that fixed-point sensors cannot cover between mounting positions. Sensor service life reaches 5 to 10 years on professional designs. This reduces replacement frequency and maintenance costs significantly across large multi-point installations.

These sensors serve Pakistan’s SSGC and SNGPL gas networks, OGDCL processing facilities in Sindh and Balochistan, WAPDA power stations, CMH hospital anaesthesia systems, pharmaceutical cleanroom programs, and HVAC automation installations across Karachi, Lahore, and Islamabad.

Tactical Supply Pakistan supplies NDIR sensors for industrial safety monitoring, clinical gas analysis, HVAC control, and process measurement procurement across Pakistan.