A thermocouple is a type of temperature sensor. It is made from two wires composed of different metals, joined together at one end to form a junction. This junction is the point at which temperature is measured. When the temperature at this junction changes, a corresponding voltage is generated.

There are many types of thermocouples, each offering unique characteristics in terms of temperature range, durability, vibration resistance, chemical resistance, and application compatibility. Types K, E, J, and T belong to the “base metal” thermocouples and are the most commonly used. Types R, S, and B are classified as “noble metal” thermocouples and are typically used for high-temperature applications (refer to the thermocouple temperature range chart for more details).

Thermocouples are widely used in industrial processes, scientific research, and by original equipment manufacturers (OEMs). They appear in nearly every industry, including power generation, oil and gas, pharmaceuticals, biotechnology, cement, and paper manufacturing. Many household appliances—such as stoves, heaters, and toasters—also rely on thermocouples.

Thermocouples are commonly chosen because they offer low cost, high-temperature capability, a wide measurement range, and robust, durable construction.