NDIR DUAL TRACE GAS ANALYZER AND METHOD FOR DETERMINING THE CONCENTRATION OF A MEASUREMENT GAS COMPONENT IN A GAS MIXTURE BY MEANS OF SUCH A GAS ANALYZER

摘要

The modulator wheel (10) of the gas analyzer contains an opening in the shadowing part thereof, said opening generating in addition to the signal component (Sa_1f, Sb_1f) at the modulation frequency (f) generated by alternating shadowing and passing-through of the radiation (2), a further signal component (Sa_2f, Sb_2f) having twice the modulation frequency (f), in the measurement signal (Sa, Sb) of the gas analyzer. The further signal component (Sa_2f, Sb_2f) is used for detecting changes to the infrared radiation source (1) or detector arrangement (12) due to contamination, aging, or temperature, and compensating for the effects thereof on the measurement result (M).