Oxygen partial pressure P_sample corresponds directly to the equilibrium oxygen partial pressure of dissolved oxygen in the molten steel, utilizing the molten steel oxygen determination. According to metallurgical thermodynamics principles (such as Sieverts' law, considering factors like temperature), the concentration of dissolved oxygen in the molten steel ([O], in units of ppm) can be directly calculated.

The Nernst equation and the ionic conductivity of zirconia are highly sensitive to temperature, exhibiting a strong dependence on it. Accurately measuring the temperature (T) of the zirconium tube itself is a prerequisite for accurately calculating the oxygen partial pressure. Operation within a specific high temperature range (such as > 650°C) is necessary to achieve good sensitivity and ionic conductivity. Below this temperature, sensitivity rapidly decreases, response times slow down, and can even become ineffective (unable to measure oxygen).