Nernst equation (%O2 calculation)

Calculation of oxygen concentration from CarboProbe sensor signal

Please enter the operating temperature (500 — 1700 deg C) and the measured mV (0 — 1200 mV) signal. The corresponding oxygen concentration is calculated. If it is very low, it is displayed in scientific notation.

Click here to download our Excel file for offline calculation

The Nernst equation is E = (RT/nF)ln(pO₂/pO₂‘)

Where:
E = sensor electromotive force, (mV)
R = gas constant
T = temperature, (Kelvin)
n = number of charges per reactant species
F = Faraday constant
p = partial pressure (mole fraction)

This equation describes the electromotive force (emf) developed when there are different concentrations of a reactant on each side of an electrolyte.

If oxygen is to be measured, using a zirconia ceramic electrolyte and atmospheric air, with pO₂ = 0.209, as a reference, this equation simplifies to:

pO₂ = 0.209 exp(-46.421 E/T)

The equation may be re-arranged, to allow calculation of the emf from a known reference concentration and a measured oxygen concentration:

E = 0.0496 T log(pO₂/0.209 )

ECONOX supplies a range of industrial, scientific and pottery probes for the measurement of oxygen at high temperature