Nitrogen Oxides (NO + NO2)

Nitrogen oxides are nitric oxide (NO) and nitrogen dioxide (NO₂). NO₂ is water-soluble and since by higher temperatures combustion gases do exceed the dew point, the following factors favouring an accurate NO_x measurement -besides the measurement principle itself- are to be considered:

• Gas transport (as quick and residue-free as possible)
• Cooling and drying of the gas to eliminate humidity
• Calibration of the measuring sensors

From the measurement technique point of view, a NO_x measurement (value calculated out of a NO and NO2 measurement) is to clearly differentiate from an NO_x calculation (calculation of NO₂ value via approximation formula out of the NO measurement result).