NDIR against Metal Oxide Films in CO2 Measurement
NDIR sensors provide definitive CO2 accuracy through direct mid-IR light absorption, while low-cost metal oxide films infer CO2 via prone cross-reactive surface chemistry.
Gas Calibration Chamber
Vessel Geometry
Sealed test vessels equipped with controlled gas inlets provide stable chemical atmospheres for sensor sensitivity calibration. A specialized gas calibration chamber allows precise delivery of target gas concentrations to test sensors under uniform pressure and temperature conditions. The apparatus governs zero and span adjustments for electrochemical and optical gas detectors.
Measurement boundaries are confined to internal chamber volumes where gas homogenization is complete, excluding external ambient conditions or unregulated sampling lines. Homogeneous gas distribution inside the chamber is maintained by internal circulation fans or optimized flow diffusers during calibration runs.
Flow Dynamics
Gas replacement rates inside the chamber dictate concentration transition speeds during span calibration steps. In a gas calibration chamber, turbulent mixing zones ensure uniform concentration across all device locations. Flow meters maintain steady volumetric delivery rates.
Material Inertness
Non-reactive internal surfaces prevent chemical adsorption of reactive gas species such as sulfur dioxide or ozone. Constructing a gas calibration chamber with PTFE or passivated stainless steel eliminates wall losses during gas exposure. Surface passivation maintains stable concentration baselines.
Traceable Testing
Calibration procedures require reference gas standards certified by national metrology institutes. Automated data acquisition systems record sensor output responses against known chamber gas concentrations. Certified calibration certificates document ambient temperature, chamber pressure, and sensor accuracy metrics.