Fe- CuNi thermocouple (type J) is also named Iron-Constantan thermocouple.. It is used in vacuum, oxidizing, inert or reducing atmospheres. Iron element oxidizes rapidly at temperatures exceeding 538'C, and therefore heavier gauge wire is recommended for longer life at these temperatures.
Type J thermocouple has good resistance to oxidation and high EMF output against Platinum 67, with good temperature accuracy, sensitivity and stability. It is recommended for vacuum, oxidizing, reducing or inert atmospheres, but it can not be used in sulphurous atmosphere above 500ºC.
Type J Temperature Range:
- Thermocouple grade wire, -346 to 1,400F (-210 to 760C)
- Extension wire, 32 to 392F (0 to 200C)
Type J Accuracy (whichever is greater):
- Standard: +/- 2.2C or +/- .75%
- Special Limits of Error: +/- 1.1C or 0.4%
Consideration for bare wire type J thermocouple applications:
- The Type J Is Well Suited To Oxidizing Atmospheres
| Code | Wires component of the thermocouple |
| | +Positive leg | -Negative leg |
| N | Ni-cr-si (NP) | Ni-si-magnesium (NN) |
| K | Ni-Cr (KP) | Ni-Al(Si) (KN) |
| E | Ni-Cr (EP) | Cu-Ni<constantan> (EN) |
| J | Iron (JP) | Cu-Ni<constantan> (JN) |
| T | Copper (TP) | Cu-Ni<constantan> (TN) |
| B | Platinum Rhodium-30% | Platinum Rhodium-6% |
| R | Platinum Rhodium-13% | Platinum |
| S | Platinum Rhodium-10% | Platinum |
| ASTM | ANSI | IEC | DIN | BS | NF | JIS | GOST |
| (American Society for Testing and Materials) E 230 | (American National Standard Institute) MC 96.1 | (European Standard by the International Electrotechnical Commission 584)-1/2/3 | (Deutsche Industrie Normen) EN 60584 -1/2 | (British Standards) 4937.1041, EN 60584 - 1/2 | (Norme Française) EN 60584 -1/2 - NFC 42323 - NFC 42324 | (Japanese Industrial Standards) C 1602 - C 1610 | (Unification of the Russian Specifications) 3044 |
Wire: 0.1 to 8.0 mm.
| Diameter/mm | Long time Working | Short period Working | | temperature/°C | temperature/°C | | 0.3,0.5 | 300 | 400 | | 0.8,1.0,1.2 | 400 | 500 | | 1.6,2.0 | 500 | 600 | | 2.5,3.2 | 600 | 750 | |
