What is the most common cause of thermocouple failures?

The most common cause of thermocouple failures is the oxidation of the hot junction. Thermocouples are temperature sensors that function by generating a voltage based on the temperature difference between two different types of metal wires joined together at the hot junction. Over time, exposure to high temperatures, particularly in oxidizing environments, can cause the materials within the hot junction to degrade. This oxidation can hinder the thermocouple’s ability to sense temperature accurately or lead to complete failure, as the chemical reactions alter the physical properties of the junction.

Oxidation affects the conductivity and stability of the junction, often resulting in fluctuating or erroneous temperature readings. Understanding this failure mode is crucial for anyone working with thermocouples, as it highlights the necessity of maintenance and proper environmental controls to ensure reliable performance over time.