This method of analysis combines the ionization of O2 and a catalytic reaction between two platinum electrodes to produce a millivolt signal representative to the concentration of O2 in the sample. This is usually an in situ measurement as the sensor operates at 736°C (1350°F) and only relies on migration of oxygen molecules within the sensor head (no extractive “sample flow” is required).
The sensor millivolts signal is mathematically converted to an oxygen concentration via the Nernst equation.
This type of sensor is affected by moisture content. It also severely affected by hydrocarbons; this is due to the hydrocarbons burning within the sensor and affecting oxygen concentrations within the sensor. Excess Sulfur is usually detrimental to the sensor too.