Thermocouple Extension & Compensation Alloys: Wire \ Strip \ Ribbon

Thermocouple Extension
& Compensation Alloys: Wire \ Strip \ Ribbon

Together with the company JLC Electromet we supply 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.

Thermocouples are connected to the temperature indicating instruments by using the leads made of same material. These leads which have the same EMF output as the thermocouple are called Extension Leads. Use of extension leads avoids lead junction error. However, for economic reasons, cheaper alloys having similar EMF output over a limited temperature range (generally 200 °C) are often used. These leads are called Compensating Leads.

We offer a full range of materials for Extension/Compensating leads. The different grades of these materials and the EMF tolerance for these grades over a required temperature range are shown in this data sheet.

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

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

We 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.

Product Forms And Dimensions

JLC products are available in wire, rod, strip, and bar forms. The dimensional capabilities in these forms readily available are listed in the table below. Additional dimensions are available by request as per customer specifications.

Product Form	Thickness	Width / Length	Supply Condition
Wire
Round Wire	0.05 mm – 12.00 mm	As Required	• Drawn • Bright • Bright Annealed • Oxidized
Flat Wire	0.5 x 0.1 mm – 6.0 x 0.8 mm	As Required	• Flat Rolled • Bright • Bright Annealed with Natural Rounded Edges • Bright Annealed with Edges as Rolled
Stranded Wire	Please Enquire	As Required
Strip
Strip	0.10 mm – 4.00 mm	Max. 110 mm width Continuous coil / spool	• Cold Rolled • Bright • Bright Annealed • Oxidized
Cold Drawn Bars
Round Bars	up to 25 mm	up to 6000 mm	• Ground • Hot Treated
Hot Finished Bars
Round Bars	20 – 75 mm	Coils / Lengths	• As Rolled • Hot Treated • Peeled • Ground

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
	Density	Electrical Resistivity at 20°C	x10^-6/°C		Thermal Linear Expansion Coeff. b/w 20-95°C	Thermal Conductivity
	g/cm³	µΩ-cm	Value	Temp range	10^-6/K	W/m K
KPX	8.72	70.6	300	20-100 °C	17.0	19.2
KNX	8.60	29.2	1900	20-100 °C	17.0	29.7
Cu Ni44	8.90	49.0	60	20-100 °C	14.0	21.4
Cu Ni43	8.90	52.0	100	20-100 °C	15.0	21.0
SX / RX	8.91	12.0	1500	20-100 °C	16.0	–
Fe	7.86	13-14	5000	20-100 °C	11.7	66.2
NPX	8.53	100.0	90	20-100 °C	17.0	13.0
NNX	8.58	36.5	680	20-100 °C	17.0	27.0

Calibration

The thermocouple grades are calibrated over the temperature range according to international specifications. All 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 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.

Size Range

The 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.

Final Inspection & Testing

Each spool/coil of thermocouple, extension and compensating alloy is calibrated according to specifications given above. The 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.