Type J thermocouple wire (Iron vs. Constantan) is suitable for vacuum, oxidizing, inert, and reducing environments. However, the iron component oxidizes rapidly above 538°C, which can affect performance. For high-temperature applications, using a thicker gauge wire is recommended to extend service life.
Chemical properties (%) | Material | Chemical composition (%) |
| Ni | Cu | Si | Iron | Al |
| JP(Iron) | | | | 100 | |
| JN(Constantan) | 45 | 55 | | | |
| Material | Density (g/cm3) | Melting point (℃) | Tensile strength (Mpa) | Volume resistivity (μΩNaN) | Elongation rate (%) |
| JP(Iron) | 7.8 | 1402 | >240 | 12.0(20℃) | >20 |
| JN(Constantan) | 8.8 | 1220 | >390 | 49.0(20℃) | >25 |
| Material | EMF value (μV) |
| 100℃ | 200℃ | 300℃ | 400℃ | 500℃ | 600℃ |
| JP-JN | 5187~ 5351 | 10696~ 10862 | 16244~ 16410 | 21760~ 21936 | 27281~ 27505 | 32962~ 33242 |
| EMF value Vs Pt(μV) |
| 700℃ | 750℃ | 760℃ | 800℃ | 900℃ | 1000℃ |
| 38958~39306 | 42089~ 42473 | 42725~ 43113 | | | |
