What are the Thermocouple Applications?

Thermocouples are the most widely used devices for temperature measurement. Study the most popular thermowell applications in industries.

Thermocouple Typical Applications

• R-type and B-type thermocouples are suitable in an oxidising atmosphere, easily contaminated in others.
• T-type can be used in oxidizing or reducing atmospheres.
• J-type can be used in reducing atmospheres. Least expensive.
• K-type can be used in oxidizing atmospheres.
• E-type is the most sensitive. It can be used in an oxidising atmosphere.

Thermocouple Advantages

• Low cost
• Small size
• Robust
• Wide range of operation
• Reasonably table
• Accurate for large temp. changes
• Fast response

Thermocouple Disadvantages

• • Weak output, mV
  • Limited accuracy for small variations in temp.
  • Sensitive to electrical noise
  • Non-linear
  • Complex conversion from emf to temp.
  • Small temperature changes mean small very small voltage changes
  • susceptible to noise
  • Non-linear
  • Calibration changes over time
  • Cannot be used bare in conductive fluids

Read Also:

• Calculations of Thermocouple
• Calibration of Thermocouple
• Types of Thermocouples
• Compensation of Thermocouple
• Errors of Thermocouple

Thermocouple Summary

• Thermocouples are the most economical elements for measuring temperature and also provide the highest ranges.
• The emf generated is independent of wire length and diameter, however, noise can be a factor.
• Thermocouples are not recommended for narrow spans or small temperature difference measurements.
• For critical temperature measurement, an accurate reference junction temperature needs to be measured and compensated for.
• T/C’s are low cost but should only be used where another element is not practical.

Detection of Thermocouple Faults

• Short in the extension wires may not be detected
• Measure resistance continuously to note any changes

Thermocouple Voltage Curves