Internationally standardized thermocouples are categorized based on their composition and temperature range. Here are the eight most commonly used types, defined by the ANSI (American National Standards Institute) and IEC (International Electrotechnical Commission) standards:

1. Type J (Iron-Constantan)

• Temperature Range: -40°C to 750°C

• Characteristics: Good for low temperatures; has a non-linear output.

2. Type K (Chromel-Alumel)

• Temperature Range: -200°C to 1260°C

• Characteristics: Widely used; good oxidation resistance and linear output. Suitable for a broad range of applications.

3. Type T (Copper-Constantan)

• Temperature Range: -200°C to 350°C

• Characteristics: Excellent for low-temperature measurements; very stable and accurate.

4. Type E (Chromel-Constantan)

• Temperature Range: -200°C to 900°C

• Characteristics: High output signal; suitable for cryogenic applications.

5. Type N (Nicrosil-Nisil)

• Temperature Range: -200°C to 1300°C

• Characteristics: Improved stability at high temperatures; good for applications in the presence of harsh environments.

6. Type R (Platinum-Rhodium)

• Temperature Range: 0°C to 1600°C

• Characteristics: High accuracy; excellent for high-temperature applications; expensive due to the noble metals used.

7. Type S (Platinum-Rhodium)

• Temperature Range: 0°C to 1600°C

• Characteristics: Similar to Type R; known for stability and accuracy; commonly used in laboratory and industrial applications.

8. Type B (Platinum-Rhodium)

• Temperature Range: 0°C to 1800°C

• Characteristics: Suitable for very high temperatures; provides high accuracy; typically used in high-temperature industrial processes.

Conclusion

These thermocouple types are standardized and used globally across various industries, including manufacturing, aerospace, and laboratory environments. Each type has specific characteristics that make it suitable for particular applications and temperature ranges.