Operating Theory

Oxygen concentration of a conventional combustion atmosphere is measured by an in situ zirconia sensor, which responds to oxygen according to the Nernst equation shown here. Because the equation is logarithmic (to the base 10), the coefficient 0.0496T_R is the number of millivolts accompanying a tenfold change in concentration:

                                             E_c= -0.02756Tr log (PR /PF) millivolts

   

where TR is the temp in degrees Rankine and PF and PR are the % oxygen (O₂) in the furnace and the reference gas.