Types and characteristics of Thermocouples What is the difference between the thermocouple types? For which temperature range can the thermocouples be used? In the following table you can see an overview of different types of thermocouples with general properties, the temperature range, material composition as well as advantages and areas of application. Information on the electrical voltage of thermocouples can be found in the table Thermoelectric voltage . Thermocouple Types and Characteristics of Thermocouples Thermocouple- types -------------- Colour- code Characteristics of Thermocouples General Composition Temperature range Suitable application Unsuitable application Type E base metal thermocouple NiCr -CuNi (nickel-chrome/copper-nickel) single wires made of non precious metals EP-leg: 89-90% nickel, 9-9.5% chrome, 0.5% silicium and iron balance: C, Mn, Nb, Co EN-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 sulp huric, reducing or alternately oxidizing, and reducing atmosphereu do not apply in vacuum for a long time Type J base metal thermocouple Fe - CuNi (iron/copper-nickel) single wires made of non precious metals JP-leg: 99.5 % iron, approx. 0.25 % manganese, approx. 0.12 % copper, balance: other impurities JN-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 Type K base thermocouple NiCr-Ni (nickel-chrome/ nickel-aluminium) single wires made of non precious metals KP-leg: 89-90% nickel, 9-9.5% chrome, 0.5 % silicium and iron balance: C, Mn, Nb, Co KN-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" Type L base thermocouple Fe - CuNi (iron/copper-nickel) single wires made of non precious metals LP-leg: 99.5 % iron, approx. 0.25 % manganese, approx. 0.12 % copper, ballance: other impurities LN-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 Type N base thermocouple NiCrSi - NiSi (nickel-chrome-silicium/nickel-silicium-magnesium) single wires made of non precious metals NP-leg: 84% nickel, 14-14.4 % chrome, 1.3-1.6% silicium, ballance (not more than 0.1%): Mn, Fe, C, Co NN-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 Type R base thermocouple Pt13%Rh - Pt (platinum 13% rhodium/ platinum) single wires made of platinum and platinum - rhodium alloy RP-leg: platinum with 99.99% purity with a rhodium alloy (purity 99.98%) 13±0.05% rhodium portion RN-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 Type S base thermocouple Pt10%Rh - Pt (platinum 10% Rhodium/ platinum) single wires made of platinum and platinum - rhodium alloy SP-leg: platinum with 99.99% purity with a rhodium alloy (purity 99.98%) 10±0.05% rhodium portion SN-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 Type B base thermocouple Pt 30%Rh - Pt 6%Rh (platinum -0% rhodium/ platinum-6% rhodium) single wires made of platinum and platinum - rhodium alloy BP-leg: platinum with 99.99% purity with a rhodium alloy (purity 99.98%) 29.60±0.2% rhodium portion BN-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 Type T base thermocouple Cu - CuNi (copper/copper-nickel) single wires made of non precious metals TP-leg: 99.95% copper, 0.02-0.07% oxygen, 0.01% impurities TN-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 Type U Unedelmetall-base thermocouple Cu - CuNi (copper/copper-nickel) single wires made of non precious metals UP-leg: 99.95% copper, 0.02-0.07% oxygen, 0.01% impurities UN-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 Do you have any questions about our products? 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