This converter is used in analysis systems which involve the need to measure total NOx in the sample, coming from plants in which the injection technique of UREA (SCR) is used to reduce NOx. In these situations, to obtain the sum of the total NOx, the emission limit frequently requires that, in addition to NO and NO2, NH3 concentration is also added. For this reason it is possible to convert all the amount of NH3 into NO, as is normally done with NO2, and it is therefore also possible to evaluate the total concentration of NOx, using only an NO analyzer.
It should also be emphasized that, in Italy, by law, the measured quantity of NOx is expressed as NO2: this implies that the concentration measured in volume must be expressed in weight as if the volume was completely occupied by NO2.
Given the extreme water solubility of the NH3, the converter is equipped with a direct connection system for a heated line.
The hot sample is conveyed in a high temperature zone, where the oxidation reaction from NH3 to NO and NO2 takes place (the last mentioned one will subsequently be converted by a molybdenum base converter).
By means of the integrated bypass, it is possible to evaluate (by difference), by reading the indications provided by the NO analyzer generally mounted downstream of the NO2/NO converter, the concentration of ammonia present in the sample.