Why use NOx filters on CO sensors?

NOx is naturally acidic gas generated through combustion applications and it can reduce the accuracy and lifespan of CO readings. The CO values in combustion sources are critical to measuring and ensuring overall safety and calculating the efficiency of the combustion process.

Gas sensor cross-sensitivity

A common issue with gas sensors is the cross-sensitivity: a sensor developed for a specific gas, can also be sensitive to other gases, known as disruptors.

This cross-sensitivity interference between CO and NOx exists unless a NOx filter is present with the CO sensor to remove the affecting gas. By comparing two gas analyzers with and without NOx filter, we can demonstrate the CO-NOx cross-sensitivity and the need for NOx filtration.

This comparison shows that if a professional is measuring CO with an analyzer without a NOx filter, the CO reading will come up at falsely high readings. CO readings have been shown to differ approximately 30% in units that do not contain a NOx filter and gets worse over time. 

Why use NOx filters on CO sensors

Built-In NOx filtration

In order to maintain the best accuracy and dependability for contractors, every Seitron's HVAC Combustion Analyzer model is equipped with Built-In NOx filtration for all CO sensors. More over, this feature also helps to prolong the life of the CO sensor by filtering out the acidic NOx gases from damaging the sensor over time. 

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