Types and characteristics of Thermocouples

General

Composition

Temperature range

Suitable application

Unsuitable application

base metal thermocouple

NiCr -CuNi
(nickel-chrome/copper-nickel)

single wires made of non precious metals

Type E (+) leg:
89-90% nickel, 9-9.5% chrome, 0.5% silicium and iron balance: C, Mn, Nb, Co

Type E (-) leg:
55% copper, 45% nickel approx. 0.1%, co balt, iron and manganese

-200°C/+700°C

• in pure, oxidizing (air), or neutral atmosphere (inert gases)

• high resistance against corrosion

• small thermal conductivit

• not sulphuric, reducing or alternately oxidizing, and reducing atmosphereu

• do not apply in vacuum for a long time

base metal thermocouple

Fe - CuNi
(iron/copper-nickel)

single wires made of non precious metals

Type J (+) leg:
99.5 % iron, approx. 0.25 % manganese, approx. 0.12 % copper, balance: other impurities

Type J (-) leg:
55% copper, 45% nickel approx. 0.1%, cobalt, iron, and manganese

-180°C/+700°C

• from 0 to 760°C in vacuum, oxidizing (air), reducing orinert atmosphere (inert gases)

• temperatures below 0°C

• sulphurous atmosphere above +500°C

• above 760°C only with bigger wire diameters

base thermocouple

NiCr-Ni
(nickel-chrome/ nickel-aluminium)

single wires made of non precious metals

Type K (+) leg:
89-90% nickel, 9-9.5% chrome, 0.5 % silicium and iron balance: C, Mn, Nb, Co

Type K (-) leg:
95-96% nickel, 1-1.5% silicium, 1-2.3 % aluminium, 1-3.2% manganese, 0.5% cobalt, balance: Fe, Cu, Pb

-270°C/+1372°C

• from 250°C to 1260°C in pure, oxidizing (air) and neutralatmosphere (inert gases)

• for higher temperatures bigger wire diameters are recommended

• between 250°C up to 600°C not suitable for exact measurements with quick temperature changes

• not appropriate for a longer time with high temperatures in vacuum

• do not apply with high temperatures in sulfurous, reducing or alternately oxidizing, and reducing atmoshere without protection

• do not use in atmosphere favourizing "green mould" 

base thermocouple

Fe - CuNi
(iron/copper-nickel)

single wires made of non precious metals

Type L (+) leg:
99.5 % iron, approx. 0.25 % manganese, approx. 0.12 % copper, ballance: other impurities

Type L (-) leg:
55% copper, 45% nickel, approx. 0.1% cobalt, iron, and manganese

0°C/+900°C

• from 0°C to 760°C in vacuum, oxidizing (air), reducing or inert atmosphere (inert gases)

• above 500°C bigger wire diameters are recommended

• Temperatures below 0°C

• sulphurous atmosphere above +500°C

• above 760°C only with bigger wire diameters

base thermocouple

NiCrSi - NiSi
(nickel-chrome-silicium/nickel-silicium-magnesium)

single wires made of non precious metals

Type N (+) leg:
84% nickel, 14-14.4 % chrome, 1.3-1.6% silicium, ballance (not more than 0.1%): Mn, Fe, C, Co

Type N (-) leg:
95 % nickel, 4.2-4.6 % silicium, 0.5-1.5 % magnesium, ballance: Fe, Co, Mn, C,
(altogether 0.1-0.3%

-270°C/+1300°C

• from 300°C to 1260°C in pure, oxidizing (air) and neutral atmosphere (inert gases)

•  do not use with high temperatures in sulphurous, reducing or alternately oxidizing, and reducing atmosphere without protection

• do not use with high temperatures in vacuum

• do not use in atmosphere faviourizing "green mould"

• reducing atmosphere

base thermocouple

Pt13%Rh - Pt
(platinum 13% rhodium/ platinum)

single wires made of platinum and platinum - rhodium alloy

Type R (+) leg:
platinum with 99.99% purity with a rhodium alloy (purity 99.98%) 13±0.05% rhodium portion

Type R (-) leg:
platinum with 99.99% purity

-50°C/+1768.1°C
(melting point) recommended:
up to +1300°C

• pure, oxidizing atmosphere (air), non aggresive (inert-) gases, and short-term in vacuum

• above +1200°C type B more appropriate

• reducing atmosphere umetal gases (for example plomb or zinc)

• agressive vapours containing arsenic, phosphor or sulphur

• do never use metal protecting tubes with higher temperatures

• sensitive against impurities of impure metals

base thermocouple

Pt10%Rh - Pt
(platinum 10% Rhodium/ platinum)

single wires made of platinum and platinum - rhodium alloy

Type S (+) leg:
platinum with 99.99% purity with a rhodium alloy (purity 99.98%) 10±0.05% rhodium portion

Type S (-) leg:
platinum with 99.99% purity

-50°C/+1768.1°C
(melting point) recommended:
up to +1300°C

• pure, oxidizing atmospheres (air), non agressive (inert-) gases, and short-term in vacuum

• above +1200°C type B more appropriate

• reducing atmosphere umetal gases (for example plomb or zinc)

• agressive vapours containing arsenic, phosphor, or sulphur

• do never use metal protecting tubes with higher temperatures

• sensitive against impurities of impure metals

base thermocouple

Pt 30%Rh - Pt 6%Rh (platinum -0% rhodium/ platinum-6% rhodium)

single wires made of platinum and platinum - rhodium alloy

Type B (+) leg:
platinum with 99.99% purity with a rhodium alloy (purity 99.98%) 29.60±0.2% rhodium portion

Type B (-) leg:
platinum with 99.99% purity with a rhodium alloy (purity 99.98%) 6.12±0.02% rhodium portion

max. +1820°C
(melting point) ordinary up to
+1700°C

• pure, oxidizing atmosphers

• neutral atmospheres

• vacuum

• reducing atmosphere or such with agressive vapoursor impurities which react with metals of the platinum group, if it is not protected with a non metal protecting tube

base thermocouple

Cu - CuNi
(copper/copper-nickel)

single wires made of non precious metals

Type T (+) leg:
99.95% copper, 0.02-0.07% oxygen, 0.01% impurities

Type T (-) leg:
55% copper, 45% nickelapprox. 0.1% cobalt, iron, and manganese

-270°C/+400°C

• from -200°C to 370°C in vacuum, oxidizing (air), reducing or inert atmosphere (inert gases)

• with higher temperatures bigger wire diameters are recommended

• above +370°C not appropriate in a hydrogen atmosphere

• not appropriate in radioactive environment

Unedelmetall-base thermocouple

Cu - CuNi (copper/copper-nickel)

single wires made of non precious metals

Type U (+) leg:
99.95% copper, 0.02-0.07% oxygen, 0.01% impurities

Type U (-) leg:
55% copper, 45% nickel approx. 0.1% cobalt, iron, and manganese

0°C/+600°C
(+400°C)

• from -200°C to 370°C in vacuum, oxidizing (air), reducing or inert atmosphere (inert gases)

• with higher temperatures bigger wire diameters are recommended

• above +370°C not appropriate in a hydrogen atmosphere

• not appropriate in radioactive environment