Introduction
Thermocouples are widely used in electric furnaces to monitor and control the temperature in a furnace. The thermocouple consists of two dissimilar metals (or low-temperature alloys) joined to form a closed circuit. When the free end of the circuit is exposed to a temperature, a small current will be generated due to the Seebeck effect, which can then be measured by a meter. The magnitude of the current is proportional to the temperature difference between two points.
Types of Thermocouple for Use in Electric Furnace
Thermocouples are used in many application processes, including in electric furnaces. In an electric furnace, thermocouples are used to monitor and control the temperature of the furnace. As the furnace temperature goes up and down, the thermocouple is used to send a signal to the furnace-controlling system to adjust the temperature accordingly. The two most common types of thermocouples used in electric furnaces are type K and type J thermocouples.
The Type K thermocouple is one of the most popular and widely used thermocouples. It is composed of chromel and alumel metal alloys. This thermocouple is reliable and accurate, and can be used to measure temperatures up to 2200°F (1204°C). It is also is less expensive than some other thermocouples, making it the most popular choice for electric furnaces.
Another type of thermocouple used in electric furnaces is type J thermocouples. This thermocouple is composed of an iron and an constantan wire. It is used for temperatures of up to 1500°F (815°C). This thermocouple is more expensive than type K thermocouples, but it offers greater accuracy and is less susceptible to corrosion.
Material Requirements for Furnace-Applied Thermocouples
Thermocouple materials must meet certain material requirements for use in an electric furnace. The two most important requirements for thermocouples are electrical resistance and temperature rating. Electrical resistance should be above 200 ohms to provide an accurate measurement without generating too much heat. The temperature rating should be above the working temperature of the furnace so that it can withstand the high temperatures of the furnace.
In addition to electrical resistance and temperature rating, thermocouples must also be made of a material that is resistant to oxidation. Oxidation can cause the temperature reading to be inaccurate or the thermocouple to fail. A material that is high in chromium or nickel content can generally provide good oxidation resistance.
Conclusion
Thermocouples are very useful in electric furnaces and can be used to monitor and control the temperature in a furnace. Type K and type J thermocouples are the two most common types used in electric furnaces but they must meet certain material requirements in order to be used safely and accurately. These requirements are electrical resistance, temperature rating, and oxidation resistance. By meeting these requirements, thermocouples can ensure accuracy, safety, and reliability for electric furnaces.
