What is a Type J Thermocouple? - Technical Information
Type J - Copper vs Copper-Nickel
Thermocouple Type J, commonly referred to as Iron/Constantan, 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 have been widely adopted in the plastics machinery industry with typical styles including bayonet thermocouples, nozzle thermocouples and melt bolt thermocouples.
Type J Thermocouples - Typical Constructions and StylesType J Mineral Insulated
Rugged sensors, ideal for most applications. Vast choice of terminations e.g. pot seals, cables, connectors, heads etc.Type J Swaged Tip
Fast response thermocouples ideal for industrial and other applications.Type J Miniature
Ideal for precision temperature measurements where minimal displacement and a fast response is required.Type J Heavy Duty
For industrial applications such as furnaces, kilns, ovens, boilers, 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 Thermocouple - Technical Data
|Conductor Combination||Approximate generated
EMF change in µV
per ºC change
(referenced to 0ºC) at:
|Initial Calibration Tolerances to ASTM E-230
(whichever is greater)
|Thermocouple Output Tolerances
to IEC 60584-1
|+ Leg||- Leg||100ºC||500ºC||1000ºC||ºF||ºC||Standard||Special||Type||Class 1||Class 2||Class 3|
Also known as: Fe
|COPPER - NICKEL
Also known as:
|54||56||59||32 to 1400||0 to 760||±2.2 or ±0.75%||±1.1 or ±0.4%||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|
1. The tolerance is expressed either as a deviation in degrees Celsius or as a function of the actual temperature.
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.
What Color is Type J Thermocouple Wire?
|ANSI MC96.1 United States||International
to IEC 60584-3
|Redundant national colors|
|Thermocouple Grade||Extension Grade||BS 1843||DIN 43714|
Please click here for all thermocouple wire color codes.
Common Type J Thermocouple Sensors for Temperature Measurement ApplicationsThermocouples with Basic End Seal 0.010" to 0.313" dia. Internal seal with bare conductors Type J Thermocouples with Pot Seal 0.010" to 0.313" dia.
a large selection of plain and threaded pot seals supplied with tails or extension Wire (PVC, FEP, Fiberglass etc.)Thermocouple Probes with Miniature Plug 0.010" to 0.125" dia.
fitted with a miniature thermocouple plug rated to either 428ºF, 572ºF, 797ºF or 1112ºFThermocouples with Miniature Jack
0.010" to 0.125" dia.
fitted with a miniature thermocouple jack rated to either 428ºF, 572ºF, 797ºF or 1112ºFwith Standard Plug
0.062" to 0.250" dia.
fitted with a standard thermocouple plug rated to either 428ºF, 572ºF, 797ºF or 1112ºFwith Standard Jack
0.062" to 0.250" dia.
fitted with a standard thermocouple jack rated to either 428ºF, 572ºF, 797ºF or 1112ºFwith Lemo Connector
0.125" to 0.250" dia. fitted with a size 1 Lemo plug
or jack with Terminal Entry Gland
0.040" to 0.313" dia. terminated with a 16mm ISO x 1.5mm compression gland seal supplied with tails or extension Wire (PVC, FEP Fiberglass etc.) with Micro die cast alloy head 0.125" to 0.250" dia. Micro die cast alloy screw down terminal head with ceramic terminal block. Suitable for simplex and duplex assemblies with Miniature IP67 die cast head 0.125" to 0.313" dia.Weatherproof die cast alloy screw top terminal head with ceramic terminal block. Suitable for simplex and duplex assemblies with Standard IP67 die cast head 0.188" to 0.500" dia. Weatherproof die cast alloy screw top terminal head with ceramic terminal block. Suitable for simplex, duplex and triplex assemblies