Thermocouple Extension & Compensation Alloys: Grade Wires

Thermocouple Extension
& Compensation Alloys: GRADES WIRES

Alloys for thermocouple applications work on the principle of Seebeck effect where an electrical voltage is generated between two dissimilar metals held at two different temperatures, a hat end and a cold end. The amount of voltage generated between the two ends of a thermocouple is directly proportional to the temperature difference. This Seebeck effect based phenomenon is used to measure the temperature of processes in a wide range of applications.

Our factory produces the entire range of Nickel and Copper based thermocouple alloys that are used in high precision temperature measurements systems. The thermocouple alloys are generally categorized in two sections:

  1. Thermocouple Grade Alloys
  2. Thermocouple Extension and Compensation Alloys

Thermocouple Extension and Compensation Alloys are used to facilitate connection between the thermocouple grade alloy wires and the temperature display unit (TDU). In many applications, the location of the temperature of interest might be inaccessible and far away from the TDU. In such cases, the thermocouple extension alloy wire, which is made of the same alloy as the thermocouple grade wire, is used as “extension” of the grade wire to carry the EMF signal to the TDU. lt is essential that the extension wire generates the same EMF output as the grade wire, generally up to 200°C.

The thermocouple compensation alloys are alternative low cost solutions to thermocouple extension alloys as they are produced primarily from lower cost metal elements. However, similar to extension wires, the compensation wires would also have to generate the same EMF output to ensure that the accuracy of the grade thermocouple wires is not compromised.

ASTM E230 – ANSI MC 96.1

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Type Temperature (°C) Special Tolerance Standard Tolerance
KX 0 to 200 ± 1.1°C ± 2.2°C
EX 0 to 200 ± 1.0°C ± 1.7°C
TX -60 to 100 ± 0.5°C ± 1.0°C
JX 0 to 200 ± 1.1°C ± 2.2°C
NX 0 to 200 ± 1.1°C ± 2.2°C
RX/SX 0 to 200 – ± 5.0°C
BX 0 to 200 – ± 4.2°C

IEC 584-3

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Type Temperature (°C) Class I Class II
KX -25 to 200 ± 1.5°C ± 2.5°C
EX -25 to 200 ± 1.5°C ± 2.5°C
TX -25 to 100 ± 0.5°C ± 1.0°C
JX -25 to 200 ± 1.5°C ± 2.5°C
NX -25 to 200 ± 1.5°C ± 2.5°C
KCA (WX) 0 to 150 – ± 2.5°C
KCB (VX) 0 to 100 – ± 2.5°C
RCA/SCA 0 to 100 – ± 5.0°C

The range of thermocouple alloys meets the specifications of American Standards by the American National Standard Institute (ANSI MC 96.1), American Society for Testing and Materials (ASTM E230) and European Standards by the International Electrotechnical Commission (IEC 584). We can also supply thermocouple alloys as per any of the following specifications: IS, DIN, BS, NF, UNI, ENI, JIS, ENEL, or GOST.

In addition, our factory has the capabilities to produce thermocouple alloys with custom Temperature-EMF curves for the positive and negative leg as per customer requests.

Form Dia (mm) AWG
Wire 0.142-8.255 0-35