Thermocouple Extension Wire | Thermocouple Alloy

Thermocouple Extension & Compensating Wire

Features

Material Composition: Made from alloys that match the thermocouple reference wire in the expected temperature range. For example, K-type thermocouples use chromel and alumel alloys, so the extension wire is also made from chromel-alumel alloys.
Operating Temperature: The rated temperature range of extension wires is lower compared to the thermocouple itself. This allows them to transmit signals from sensors in high-temperature environments to cooler control areas.
Accuracy: Designed to maintain the original voltage-temperature relationship of the thermocouple. Any deviation can lead to errors, making it crucial to select the correct extension wire type.
Insulation: Insulated using materials suitable for the environment, such as PVC, Teflon, or fiberglass, to ensure reliable performance.

Differences Between Thermocouple Wire and Extension Wire

Feature	Thermocouple Wire	Extension Wire
Material	Same as Thermocouple Alloy	Matches only within the specified temperature range
Temp Change	High (some types up to 1,700°C)	Limited (usually up to 400°C)
Cost	Higher	Reduced
Purpose	Used for temperature sensing	Extends the temperature signal to instrumentation

Main Considerations When Choosing Thermocouple Extension Wires

Match thermocouple type: The extension wire must correspond to the thermocouple type (e.g., K, J, T).
Operating environment: Ensure that the insulation material is suitable for temperature, humidity, or chemical exposure conditions.
PVC: Flexible, general-purpose.
Fiberglass: High-temperature resistant.
PTFE (Teflon): Chemical and moisture resistant.
Wire gauge: Heavier gauges are needed for long distances or harsh environments to minimize signal loss.
Shielding: For environments with electrical interference, consider using shielded wire.
Accuracy: Verify whether the wire meets ASTM or IEC standards for accuracy.

Applications