Characteristics and Application of S-type and B-type Thermocouples Used in Thermal Industrial Muffle

Characteristics and Application of S-type and B-type Thermocouples Used in Thermal Industrial Muffle Furnaces

The S-type and B-type thermocouples used in muffle furnaces are two common high-temperature measuring elements, each with different characteristics and applicable ranges. The following are the main differences and uses of these two types of thermocouples:

Basic principle of thermocouple

Firstly, understanding the working principle of thermocouples helps to better comprehend their applications. Thermocouples work by connecting two conductors of different materials into a closed loop. When these two contacts are at different temperatures, an electromotive force (i.e. thermoelectric potential) is generated in the circuit, which is proportional to the temperature difference.

S-type thermocouple

Characteristics

Composition material: The S-type thermocouple is composed of 10% platinum rhodium (positive electrode) and pure platinum (negative electrode).

Strong oxidation resistance: S-type thermocouples exhibit good stability and oxidation resistance in oxidizing or neutral atmospheres due to their material properties, making them suitable for long-term use in high-temperature environments.

Wide temperature measurement range: S-type thermocouples can reach temperatures of up to 1400 ℃ for long-term use and up to 1600 ℃ for short-term use.

High precision: Among all types of thermocouples, S-type thermocouples have a higher precision level and are usually used as standard reference thermocouples.

Purpose

Laboratory and industrial applications: Due to its high precision and stability, S-type thermocouples are widely used in high-temperature measurements in scientific research, metallurgy, chemical engineering, and other fields.

Special Environment: Suitable for processes that require precise temperature control, such as material sintering, heat treatment, etc.

B-type thermocouple

Characteristics

Composition material: B-type thermocouple is composed of 30% platinum rhodium (positive electrode) and 6% platinum rhodium (negative electrode).

Superior high-temperature performance: B-type thermocouples are particularly suitable for measurement at extremely high temperatures, with a measurement range of 800 ℃ to 1820 ℃, and can maintain stable operation at higher temperatures.

No need for low-temperature compensation: For B-type thermocouples, the thermoelectric potential is less than 3 μ V within the temperature range of 0-50 ℃, so cold junction temperature compensation can be omitted within this temperature range.

Purpose

Temperature measurement under extreme conditions: B-type thermocouples are mainly used in applications that require measuring very high temperatures, such as high-temperature monitoring in ceramic and glass manufacturing processes.

Scientific research: In research projects that require accurate measurement of extremely high temperatures, B-type thermocouples are an ideal choice.

The choice between S-type or B-type thermocouples depends on the specific application requirements. If the application scenario involves high temperatures but not exceeding 1600 ℃ and requires high measurement accuracy, S-type thermocouples can be selected; For situations where it is necessary to measure extremely high temperatures such as over 1600 ℃ or even close to 1800 ℃, B-type thermocouples should be selected. In addition, considering cost factors, S-type thermocouples are relatively expensive because they contain more precious metal components. Therefore, in practical operation, the most suitable thermocouple type should be determined based on specific experimental or production conditions.