Thermocouples come in various types, each with specific properties suited to different temperature ranges, environmental conditions, and accuracy requirements. These types—commonly designated as J, K, T, E, N, R, S, and B—are standardized combinations of metals that generate a voltage corresponding to temperature.
Understanding the differences between these types is essential for choosing the right thermocouple for your application.
Common Thermocouple Types
Type J (Iron–Constantan)
- Temperature Range: 0 to 760 °C (32 to 1400 °F)
- Sensitivity: ~50 µV/°C
- Environment: Best for oxidizing, reducing, or inert atmospheres
- Notes: Not recommended for use above 760 °C due to iron oxidation
Type K (Chromel–Alumel)
- Temperature Range: −200 to 1260 °C (−328 to 2300 °F)
- Sensitivity: ~41 µV/°C
- Environment: Excellent in oxidizing or inert atmospheres
- Notes: Most widely used general-purpose thermocouple; good high-temp stability
Type T (Copper–Constantan)
- Temperature Range: −200 to 370 °C (−328 to 700 °F)
- Sensitivity: ~43 µV/°C
- Environment: Ideal for cryogenic and low-temp applications
- Notes: Very stable and accurate at low temperatures
Type E (Chromel–Constantan)
- Temperature Range: −200 to 900 °C (−328 to 1650 °F)
- Sensitivity: ~68 µV/°C (highest among base metal types)
- Environment: Works well in inert and oxidizing environments
- Notes: High sensitivity makes it suitable for low signal applications
Type N (Nicrosil–Nisil)
- Temperature Range: −200 to 1300 °C (−328 to 2372 °F)
- Environment: Excellent resistance to oxidation and drift
- Notes: Good for high-temp applications where long-term stability is important
Types R, S, B (Platinum–Rhodium Types)
- Temperature Range: Up to 1700 °C (3092 °F)
- Environment: High-temperature applications such as furnaces or kilns
- Notes: More expensive; used in lab, aerospace, and high-temp process control
Which Thermocouple Type Should I Choose?
The best thermocouple type depends on your temperature range, environment, and required accuracy.
| Application | Recommended Type |
|---|---|
| General-purpose industrial | Type K or J |
| Low-temperature or cryogenic | Type T |
| High-accuracy lab use | Type T or E |
| High-temp furnaces | Type R, S, or B |
| Harsh, oxidizing conditions | Type K or N |
| Applications prone to drift | Type N |
Need Help Choosing?
HGSI offers custom-built thermocouples in Type J, K, T, and more—optimized for your specific needs. Whether you're monitoring engine components, conducting R&D, or automating an industrial process, we’re here to help you select the right sensor.
Contact us today to speak with our experienced application engineers.