There are two calibration of zirconia oxygen analyzers. First one is Two Point calibration and second is One Point Calibration.
Zirconia Oxygen Analyzers Calibration
The two-point calibration using two gases: zero and span.
Cell electromotive forces for a span gas with an oxygen concentration p1 and a zero gas with an oxygen concentration p2 are measured while determining the calibration curve passing between these two points.
The oxygen concentration of the measurement gas is determined from this calibration curve.
In addition, the calibration curve corrected by calibration is compared with the theoretical calibration curve for determining the zero-point correction ratio represented by B/A 100 (%) on the basis of A, B and C shown in the standard figure and a span correction ratio of C/A 100 (%).
If the zero-point correction ratio exceeds the range of 100 30 % or the span correction ratio becomes larger than 0 18 %, calibration of the sensor becomes impossible.
The one-point calibration using only a span gas. In this case, only the cell electromotive force for a span gas with oxygen concentration p1 is measured.
The cell electromotive force for the zero gas is carried over from a previous measurement to obtain the calibration curve.
The principle of calibration using only a span gas also applies to the one-point calibration method using a zero gas only.