Teledyne 3290 - OEM percent oxygen analyzer - Manual (Page 21)

Percent Oxygen Analyzer Operational Theory
Teledyne Analytical Instruments 11
2.2.5 Calibration Characteristics
Given that the total pressure of the sample gas at the surface of the
oxygen sensor input is constant, a convenient characteristic of the cell is
that the current produced in an external circuit of constant impedance is
directly proportional to the rate at which oxygen molecules reach the
cathode, and this rate is directly proportional to the concentration of
oxygen in the gaseous mixture. In other words it has a linear
characteristic curve, as shown in Figure 2-2. Measuring circuits do not
have to compensate for non-linearities.
Figure 2-2: Input/Output Curve for a Typical Oxygen Sensor
In addition, since there is zero output in the absence oxygen, the
characteristic curve has an absolute zero. The cell itself does not need to
be zeroed.