Thermocouple Colour Chart

In a broad sense, a thermocouple is a junction between two different metals that produce a voltage related to a temperature difference.

Thermocouples are a widely used type of temperature sensor for measurement and control, and can also be used to convert heat gradients into electricity.

Thermocouples are inexpensive and interchangeable and are supplied fitted with standard connectors, and can measure a wide variety of temperatures.  

Thermocouples are widely used in science and industrial applications to include temperature measurements for kilns, gas turbines, exhausts, engines and other industrial processes.

The most common usage of thermocouples are in temperature sensors. They are rugged, low-cost, dependable and fairly accurate over a useful temperature range up to 2300 °C.  Unforuntately, thermocouples are less suitable for applications where smaller temperautr difference need to be measured with high accuracy, for example the ranges with 0-100 °C with 0.1 °C accuracy.

Thermocouple Grades & Combinations

Thermocouple wiring is available in several different metallurgical formulations per type, typically, in decreasing levels of accuracy and cost: special limits of error, standard, and extension grades.

Over the years, certain combinations of alloys have become popular as industry standards selections. Selection of the thermocouple combinations are typically driven by cost, availability, convenience, melting point, chemical properites, stability and output.

Different types of thermocouples are suitable for different types of applications. Thermocouples are usually selected based upon the temperature range and sensitivity needed. Thermoucples which have low sensitivites such as (B,R, and S types) have correspondingly lower resolutions.

Other selection criteria to consider when using thermocouple is the inertness of the thermoucple material, and whether it is magnetic or not.  

Different industries around the world, categories their thermocouple code ranges into different categories. To help explain the colour codes and labels, this handy thermocouple help sheet should explain the difference.

If you have a specific enquiry into thermocouples, feel free to contact us and one of our technical advisors will explain in greater in depth.