Cuprothal®

Thermocouple wireDatasheet

Datasheet updated 2024-09-09 10:06 (supersedes all previous editions)

Disclaimer: Recommendations are for guidance only, and the suitability of a material for a specific application can be confirmed only when we know the actual service conditions. Continuous development may necessitate changes in technical data without notice. This datasheet is only valid for materials under the trademark Kanthal^®.

Cuprothal^® thermocouple wire is an austenitic copper-nickel alloy (CuNi alloy) with low resistivity. It is used for the negative leg of the following types of thermocouples and compensating cables: E, J, T and KCB (VX). Cuprothal^® can be used at temperatures down to 20 K where its Seebeck coefficient is about 8 μV / K.

Thermocouple type E has the highest emf output of any common thermocouple and is for this reason used in thermal generators (thermopiles).

Cuprothal^® thermocouple wire type T is matched with electrolytic copper (ASTM standard B3). Thermocouple type T is both used in laboratory and industrial applications.

Cuprothal^® type KNCB (VNX) is matched with electrolytic copper when used in compensating cables for thermocouples type K.

Chemical composition

	Ni %	Mn %	Fe %	Co %	Cu %
Nominal composition	44.0	0.5	0.5	0.3	Bal.

Mechanical properties

Wire size	Yield strength	Tensile strength	Elongation	Hardness
Ø	R_p0.2	R_m	A
mm	MPa	MPa	%	Hv
2.00	250	480	30	130

Physical properties

Density g/cm³	8.9
Electrical resistivity at 20°C Ω mm²/m	0.49

Temperature factor of resistivity
Temperature °C	100	200	300	400	500	600
Ct	1.002	1.002	1.001	1.005	1.017	1.037

Coefficient of thermal expansion
Temperature °C	Thermal Expansion x 10^-6/K
20 - 100	14

Thermal conductivity
Temperature °C	20
W m^-1 K^-1	21

Specific heat capacity
Temperature °C	20
kJ kg^-1 K^-1	0.410

Melting point °C	1280
Magnetic properties	The material is non-magnetic

Recommended maximum continuous operating temperatures for type JN
Wire size Ø	3.26	1.63	1.00	0.50	0.25
Bare wire °C	760	760	720	650	560
Protected wire °C	760	760	760	760	670

Note that the indicated temperatures should be considered as guide values

Recommended maximum continuous operating temperatures for type EN
Wire size Ø	3.26	1.63	1.00	0.50	0.25
Bare wire °C	890	800	750	660	580
Protected wire °C	1000	910	860	770	690

Note that the indicated temperatures should be considered as guide values

Thermoelectric properties

CUPROTHAL™JN - JNX

Nominal emf values vs Iron
Temperature °C	100	200	300	400	500	600	700	800
mV	5.269	10.779	16.327	21.848	27.393	33.102	39.132	45.494

ITS 90 - Reference junction 0°C

CUPROTHAL^®TNX - TN

Nominal emf values vs electrolytic copper (ASTM B3)
Temperature °C	100	200	300	400
mV	4.279	9.288	14.862	20.872

ITS 90 - Reference junction 0°C

CUPROTHAL^®EN - ENX

Nominal emf values vs Thermothal P (KP)
Temperature °C	100	200	300	400	500	600	700	800	900	1000
mV	6.319	13.421	21.036	28.946	37.005	45.093	53.112	61.017	68.787	76.373

ITS 90 - Reference junction 0°C

CUPROTHAL^®KNCB (VNX)

Nominal emf values vs electrolytic copper (ASTM B3)
Temperature °C	100
mV	4.096

ITS 90 - Reference junction 0°C

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Cuprothal®

Chemical composition

Mechanical properties

Physical properties

Thermoelectric properties

CUPROTHAL™JN - JNX

CUPROTHAL®TNX - TN

CUPROTHAL®EN - ENX

CUPROTHAL®KNCB (VNX)

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CUPROTHAL^®TNX - TN

CUPROTHAL^®EN - ENX

CUPROTHAL^®KNCB (VNX)