How much Oxygen do sensors need to function correctly?
Sensors which generate an output by oxidising the target gas such as carbon monoxide sensors need a supply of oxygen to the counter electrode to support the balancing oxygen reduction reaction which takes place there. Generally a few thousand ppm at most is required to support this and this may be provided by the level of oxygen in the sample gas. Even where the sample gas is anaerobic there is enough oxygen inside the sensor to support short exposures. The reference electrode also requires a small supply of oxygen for most sensors so that if a sensor is operated continuously in an anaerobic environment it will eventually start to misread.
