Available from stock
Type J thermocouple wire
Type J, Fe-CuNi thermocouple is a widely used thermocouple junction. In general, it is economically priced and it has a smaller temperature range compared to other thermocouple junctions: -210°C to +750°C. Type J thermocouples are favored for their low cost and high EMF, making them suitable for industrial applications.
These thermocouple wires feature iron-constantan conductors but have a slightly smaller temperature range compared to type K thermocouples and are not ideal for oxidising environments. Caution is advised as the iron leg can rust if exposed to moisture.
Type J thermocouple wire specifications
| Specification | Type J bare thermocouple wire |
|---|---|
| Thermocouple type | Type J |
| Conductor combination | Fe-CuNi |
| Positive leg (JP) | 100% Fe |
| Negative leg (JN) | 45% Ni / 55% Cu |
| Overall stated temperature range | -210°C to +750°C |
| Standard tolerance | IEC 60584 Class 1 |
| Available diameters | Ø0.80–3.90 mm |
| Certificates | 3.1 material certificate + calibration certificate |
| Suitable environments | Reducing, inert and vacuum |
| Environmental limitation | Not ideal for oxidising environments |
| Additional limitation | Not recommended in sulphurous atmospheres above 500°C |
| Other consideration | Iron leg can rust when exposed to moisture |
Our standard type J wire
Please contact us if you need different diameters. We can supply more custom made diameters (combinations) than stated below.
| Thermocouple | Class | Outside Diameter in mm | On Stock | |
|---|---|---|---|---|
| Type J | Class 1 | 0.30 mm | – | Send inquiry |
| Type J | Class 1 | 0.80 mm | Yes | Send inquiry |
| Type J | Class 1 | 1.00 mm | Yes | Send inquiry |
| Type J | Class 1 | 1.50 mm | – | Send inquiry |
| Type J | Class 1 | 2.00 mm | Yes | Send inquiry |
| Type J | Class 1 | 3.00 mm | – | Send inquiry |
Delivery times stated are for delivery to Kamet’s warehouse
When should you use Type J thermocouple wire?
Type J thermocouple wire is used for industrial temperature measurement where its stated temperature range, relatively high EMF and suitability for reducing, inert or vacuum environments match the application requirements. Applications mentioned by Kamet include plastics and resin manufacturing and other industrial temperature monitoring processes.
Which environments are suitable for Type J thermocouple wire?
Type J thermocouple wire is suitable for reducing and inert environments and for use in vacuum at temperatures up to 750°C according to the stated product guidance.
When should Type J thermocouple wire not be used?
Type J is not ideal for oxidising environments, and the iron positive leg can rust when exposed to moisture. The current product guidance also states that Type J is not recommended in sulphurous atmospheres above 500°C.
How can we help you today?
Request a quotation for the wire and quantity you need for your project.
Specifications and physical properties
Operating temperature
Approximate working temperature range;
- Continues: +20 to +700°C
- Short term: –210 to +750°C
Please note that these ranges are given as indicative values and vary per diameter.
What are Type J thermocouple wires made of?
The Type J thermocouple pair consists of an iron positive leg (JP) and a copper-nickel negative leg (JN). The stated composition is 100% Fe for JP and 45% Ni / 55% Cu for JN.
- JP ( + ) = 100% Fe
- JN (-) = 45%Ni 55% Cu
Physical properties
| JP | JN | |
|---|---|---|
| Density (g/cm3) | 7.86 | 8.90 |
| Melting point (°C) | 1535 | 1210 |
| Temp. coef. of resistance (x10-6/°C) | 5000 | 60 |
| Linear expansion (coef. x10-6/°C) | 11.7 | 14 |
| Thermal Conductivity (W m-1 °C-1 at 20°C) | 66.2 | 21.2 |
JP/JN EMF reference table (mV)
The table below provides the stated Type J JP/JN electromotive force (EMF) reference values in millivolts as a function of temperature.
| °C | 0 | 10 | 20 | 30 | 40 | 50 | 60 | 70 | 80 | 90 | 100 |
| 0 | 0 | 0.507 | 1.019 | 1.536 | 2.058 | 2.585 | 3.115 | 3.649 | 4.186 | 4.725 | 5.268 |
| 100 | 5.268 | 5.812 | 6.359 | 6.907 | 7.547 | 8.008 | 8.56 | 9.113 | 9.667 | 10.222 | 10.777 |
| 200 | 10.777 | 11.332 | 11.887 | 12.442 | 12.998 | 13.553 | 14.108 | 14.663 | 15.217 | 15.771 | 16.325 |
| 300 | 16.325 | 16.879 | 17.432 | 17.984 | 18.537 | 19.089 | 19.64 | 20.192 | 20.743 | 21.295 | 21.846 |
| 400 | 21.846 | 22.397 | 22.949 | 23.501 | 24.054 | 24.607 | 25.161 | 25.716 | 26.272 | 26.829 | 27.388 |
| 500 | 27.388 | 27.949 | 28.511 | 29.075 | 29.642 | 30.21 | 30.782 | 31.356 | 31.933 | 32.513 | 33.096 |
| 600 | 33.096 | 33.683 | 34.273 | 34.867 | 35.464 | 36.066 | 36.671 | 37.28 | 37.893 | 38.51 | 39.13 |
| 700 | 39.13 | 39.754 | 40.382 | 41.013 | 41.647 | 42.283 | 42.922 | 43.563 | 44.207 | 44.852 | 45.498 |
| 800 | 45.498 | 46.144 | 46.79 | 47.434 | 48.076 | 48.716 | 49.354 | 49.989 | 50.62 | 51.249 | 51.875 |
Other products in this category
Type K
NiCr-Ni bare wire -270°C to +1260°C
Type N
NiCrSil-NiSil bare wire -270°C to +1260°C
Type E
NiCr-CuNi bare wire -270°C to +900°C
Type T
Cu-CuNi bare wire -270°C to +370°C
Type S
Pt10%Rh-Pt bare wire -50°C to +1600°C
Type R
Pt13%Rh-Pt bare wire -50°C to +1450°C
Type B
Pt30%Rh-Pt6%Rh bare wire 600°C to 1700°C