Why can tungsten tube be used as a thermocouple protective cover?
There are several reasons why tungsten tubing is used as a thermocouple sheath, especially in high temperature applications. The following are the key factors that make tungsten an excellent choice for this purpose:
1. High melting point
– Tungsten has an extremely high melting point of approximately 3422°C (6192°F). This allows it to withstand extreme temperatures without deforming or melting, making it ideal for high temperature environments where thermocouples are often used.
2. Thermal conductivity
– Tungsten has good thermal conductivity, allowing for rapid heat transfer. This property ensures that the thermocouple responds quickly to temperature changes, providing accurate and timely readings.
3. Mechanical Strength
– Tungsten is known for its high tensile strength and durability. This mechanical strength enables the protection tube to withstand physical stresses such as thermal cycling and mechanical shock without compromising its integrity.
4. Antioxidant
– Tungsten has good oxidation resistance in inert or vacuum environments. This is critical to maintaining the performance of thermocouples in high temperature applications, as oxidation will cause the protective layer to degrade and fail.
5. Chemical stability
– Tungsten is chemically stable and resistant to a variety of corrosive environments, helping to protect thermocouples from chemical attack in a variety of industrial applications.
6. Low thermal expansion
– Tungsten has a low coefficient of thermal expansion, which means it does not expand or contract significantly with changes in temperature. This property helps maintain the dimensional stability of the protection tube, ensuring a consistent fit with the thermocouple.
7. Compatibility with Thermocouples
– Tungsten can be used with various types of thermocouples (e.g., Type K, Type S) without introducing significant errors in the temperature measurement. Its properties do not interfere with the thermoelectric properties of the thermocouple material.
8. High Purity Option
– Available in high purity tungsten (99.95% or higher) to minimize contamination and ensure accurate and reliable thermal readings.