Recently, we set about testing the relationship between the rate at which air is circulated through a wide-range CO2 sensor and the speed and accuracy of the reading. The tests lead to 3 results:
1. Over short periods of time a CO2 sensor is more accurate if the gas is circulated (fan, etc.) around it.
2. Over short periods of time a CO2 sensor with an air-pump pushing gas over it reacts more quickly, and CO2 levels fall off faster than the same sensor dependent on diffusion or a fan for air circulation.
3. Over long periods of time (~18 minutes) a CO2 sensor’s accuracy is independent of air circulation.
For a full discussion, read the App Note with graphs here.