REDWIRE Common Thermocouple Issues and How to Avoid Them, from Thermo-Kinetics

September 28, 2021 REDWIRE is news you can use from leading suppliers. Powered by FRASERS.

Posted by Thermo-Kinetics Measurement & Control Ltd.


For over 40 years, Thermo-Kinetics has been working with clients to find innovative solutions for process control and me... Read more

Contact supplier


Subscribe
Free REDWIRE e-newsletter

Thermo-Kinetics is a top source of thermocouples.

Thermo-Kinetics Measurement & Control Ltd. manufactures a variety of thermocouples. These devices offer accurate results when used and calibrated properly. But certain issues may occur and cannot necessarily be avoided. As experts in measurement solutions, Thermo-Kinetics pinpoints the most common of these issues, so users can be prepared to check thermocouple accuracy and, if required, replace instruments more often if their processes undergo numerous large cycles.

10 Rules of Thumb for Thermocouple Applications

  1. Poor location is a frequent problem: when a thermocouple is in a dead spot in a furnace or directly in front of a flame, it may not be accurate.
  2. Sagging is another common issue; users should install them vertically, which makes them easier to remove.
  3. Thermocouples should always be kept away from electric motors and high-voltage wires to prevent induced voltage.
  4. Thermocouples should be left alone after installation; handling them can break the fragile wires. If the user must move the instrument, it should be kept straight and installed to at least the same depth level.
  5. Thermocouple accuracy can be affected if not installed deep enough. Thermo-Kinetics recommends installing eight-to-ten times the diameter of the probe into the medium that is to be measured. Otherwise, the sheath may affect readings by acting as a heat sink.
  6. Larger thermocouples offer longer lifespans and higher stability, but this must be balanced with cost-response time and size limits.
  7. Contamination can occur when a platinum thermocouple is used, even the insulator and protection tube may cause problems. One should use high-purity alumina, since some lower-grade insulators contain silica that emits silicon gas when heated, and this attacks the wires.
  8. Users should also be aware that thermocouples drift with time, and drift is directly proportional to the number and magnitude of cycles. It is not uncommon to see a K-Type thermocouple drift up to 120 degrees Celsius.
  9. For troubleshooting, Thermo-Kinetics suggests inspecting thermocouples for wear, damage, or corrosion. This process involves disconnecting the instrument, using a potentiometer to compare readings with another thermocouple and simulate a reading back through the wires, and then feeding a signal directly to it after disconnection to verify accuracy.
  10. Finally, source your thermocouples and RTDs from a trusted, local manufacturer with over 50 years of experience in the field and an ISO 17025-accredited lab, to ensure the most accurate temperature measurements.

For more information, contact Thermo-Kinetics or call 1-800-268-0967.


Share

Posted by Thermo-Kinetics Measurement & Control Ltd.


For over 40 years, Thermo-Kinetics has been working with clients to find innovative solutions for process control and me... Read more

Contact supplier