Data Sheet: Thermocouple Grade Alloys


Learn more about each nickel speciality alloy

  • Thermocouple Grade Alloys

Thermocouple Grade Alloys: Wire \ Strip \ Ribbon

JLC produces a wide range of alloys that are used to manufacture thermocouples, extension and compensating wires/cables. Thermocouples are formed by joining two dissimilar alloys that will produce a thermal EMF when the junctions are at different temperatures. Different grades of thermocouple alloys are used depending upon the temperature being measured.

Forms of Supply

Cold Drawn, Annealed.
Oxidized wire surface is also available for applications where corrosive atmosphere is present.

Specifications

JLC range of thermocouple alloys meets the specification of ASTM E 230 and ANSI MC 96.1.

JLC can also manufacture thermocouple alloys to conform to any of the following specifications: IS, IEC, DIN, BS, NF, UNI, ENI, JIS, ENEL, or GOST. Special tolerances and properties can be made available upon customer request.

JLC Thermocouple Alloys (According to ASTM E230 and ANSI MC96.1)

Type

K
KP-KN
J
JP-JN
E
EP-EN
T
TP-TN
N
NP-NN
Temp EMF Tolerance EMF Tolerance EMF Tolerance EMF Tolerance EMF Tolerance
°C mV °C % mV °C % mV °C % mV °C % mV °C %
-200 - ± 2.2 ± 2 - - - - - - -5.603     - - -
-100 - - - -3.378     -
0 0 -   0 - - 0 - - 0 - - 0 - -
100 4.095 ±2.2 ±0.75 5.268 ±2.2 ±0.75 6.317 ±1 ±0.50 4.277 ±1 ±0.75 2.773 ±2.2 ±0.75
200 8.137 10.777 13.419 9.286 5.911
300 12.207 16.325 21.033 14.860 9.340
400 16.395 21.846 28.943 20.869 - 12.972
500 20.640 27.388 36.999 - 16.744
600 24.902 33.096 45.058 - 20.609
700 29.128 39.130 53.110 - 24.525
800 33.277 45.498 - 61.022 - 28.456
900 37.325 - 68.783 - 32.370
1000 41.269 - - - - 36.248
1100 45.108 - - - 40.076
1200 48.828 - - - 43.835
1300 52.398 - - - - 47.502 - -

Standard & Special grades

The EMF tolerance of standard grade of alloys is according to the table presented on the previous page. JLC's special grades offer closer tolerances (½ and ¼ of standard grades) for applications where higher accuracy is needed.

Calibration

JLC thermocouple grades are calibrated over the temperature range according to international specifications. All our grades are individually calibrated versus NBS Pt 67. Each coil/spool is tested for EMF and value of deviation from the standard EMF at different temperatures is shown on the labels attached to each coil/spool. All JLC thermocouple materials are made confirming to EMF/temperature requirements for thermocouples as per NBS monograph 125. Alternatively, calibration is also performed as per ASTM E220 comparison technique.

Nominal Physical, Electrical & Mechanical Properties (at room temperature for annealed wire)

Alloy Density Electrical Resistivity
at 20°C
Temp Coeff of Resistance Thermal Linear
Expansion Coeff.
b/w 20-95°C
Thermal Conductivity
x10-6/°C
g/cm³ µΩ-cm Value Temp range 10-6/K W/m K
KP/ EP 8.72 70.6 300 20-100°C 17.0 19.2
KN 8.60 29.2 1900 20-100°C 17.0 29.7
EN/JN/TN 8.90 49.0 60 20-100°C 14.0 21.4
Fe 7.86 13-14 5000 20-100°C 11.7 66.2
NP 8.53 100.0 90 20-100°C 17.0 13.0
NN 8.58 36.5 680 20-100°C 17.0 27.0

Note: JP is Iron and needs to be supplied in calibrated form, always along with JN. TP is regular electrolytic Copper.

Final Inspection & Testing

Each spool/coil of JLC thermocouple, extension and compensating alloy is calibrated according to specifications given above. JLC thermocouple alloys are fully tested for homogeneity of chemical composition, physical, and thermoelectric properties. This includes the testing of electrical resistivity (loop resistance), which is an important property of thermocouple alloys.

Size Range

JLC thermocouple materials are available in different sizes (mm/AWG/SWG) or resistance based upon customer's requirement.

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

Strips and ribbons are also available in various sizes upon request.

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