Type J Thermocouple - Technical Information
Type J - Iron vs Copper-Nickel, IEC 60584-1
Thermocouple Type J, commonly referred to as Iron/Constantan, this is one of the few thermocouples that can be used safely in reducing atmospheres. However, in oxidising atmospheres above 550°C, degradation is rapid. Maximum continuous operating temperature is around 800°C, although for short term use, temperatures up to 1,000°C can be handled. Minimum temperature is -210°C, but beware of condensation at temperatures below ambient - rusting of the iron arm can result, as well as low temperature embrittlement.
Type J Thermocouples - Typical Constructions and StylesType J Mineral Insulated
Thermocouples Rugged sensors, ideal for most applications. Vast choice of terminations e.g. pot seals, cables, connectors, heads etc.Type J Swaged Tip
Thermocouples Fast response thermocouples ideal for industrial and other applications. Type J Miniature
Thermocouples Ideal for precision temperature measurements where minimal displacement and a fast response is required. Type J Heavy Duty
Thermocouples For industrial applications such as furnaces, kilns, ovens, boliers, flues etc. Many types of sheath material available. General Purpose
Type J Thermocouples A wide range of thermocouples to suit many applications. Hand held, surface, bayonet, bolt, patch styles etc. ATEX/IECEx Approved
Type J Thermocouples A large range of thermocouples with a variety of terminations such as pot seal, terminal heads etc.
Type J - Technical Data
|Conductor Combination||Approximate generated
EMF change in µV
per ºC change
(referenced to 0ºC) at:
|Thermocouple Output Tolerances|
to IEC 60584-1
|+ Leg||- Leg||100ºC||500ºC||1000ºC||Continuous||Short Term||Type||Class 1||Class 2||Class 3|
Also known as: Fe
|COPPER - NICKEL
Also known as:
|54||56||59||+20 to +700°C||–180 to +750°C||Temperature Range
|–40°C to +375°C
375°C to 750°C
|–40°C to +333°C
333°C to 750°C
±0.0075 ⋅ |t|
2. Thermocouple materials are normally supplied to meet the tolerances specified in the table for temperatures above –40 deg C. These materials however, may not fall within the tolerances for low temperatures given under Class 3 for Types T, E and K thermocouples. If thermocouples are required to meet limits of Class 3, as well as those of Class 1 and/or Class 2, the purchaser should state this, as selection of materials is usually required.
3. The maximum temperature rating is dependant upon construction, size and atmospheric conditions. A more detailed guide for the maximum temperature ratings of mineral insulated thermocouples can be found here.
J Type Cable Colour Codes for Thermocouples
|International Colour Code to IEC 60584-3||ANSI MC96.1||Redundant national colour coding for thermocouple cables|
|BS 1843||DIN 43714||NFC 42324|