Thermocouples are needed when high temperatures need to be measured or temperatures in hazardous environments, such as environments with high vibration or with toxic gasses. They are less common when high precision measurement is required for temperature ranges varying from 0 to 300°C. For this temperature range RTDs are more accurate.
What kind of thermocouple sensor do I need?
This depends on the temperature you need to measure. The thermocouple alloys are described as types. For example, a type K thermocouple alloy contains a NiCr-Ni junction, providing the widest operating range of all thermocouples. Below you can find a list of temperature ranges for each thermocouple type. When choosing a thermocouple for your application, keep in mind that the diameter of the sensor can have an impact on the application range and the lifetime of the sensor.
| Thermocouple wire types | Useful application range |
|---|---|
| Type K | -270°C to +1260°C |
| Type N | -270°C to +1260°C |
| Type J | -210°C to +760°C |
| Type E | -270 to +900°C |
| Type T | -270°C to +370°C |
| Type R | -50°C to +1480°C |
| Type S | -50°C to +1480°C |
| Type B | 0°C to +1700°C |
What are the most common thermocouple junctions?
The most common thermocouple junction is a type K (NiCr-Ni) junction. This type of thermocouple junction has the widest temperature range of all thermocouple types. Furthermore, type K thermocouples tend to be cost-efficient, accurate and reliable.
In the 1960’s, the type N (NiCroSil-NiSil) thermocouple was developed. This thermocouple type had a positive effect on short range ordering. The type N and type K thermocouples share the same accuracy and temperature range, but type N thermocouples tend to be more stable.
Is there a difference between a thermocouple probe, sensor and insert?
No there is not. These three words are commonly used to describe the same themperature sensor using thermocouple wires.
Discover more about mineral insulated thermocouple cable and here for complete thermocouple sensors assemblies.