Type N Thermocouple Wire: Nicrosil / Nisil, −270 … +1300 °C
Nicrosil (NiCrSi 84.4/14.2/1.4)
Nisil (NiSiMg 95.4/4.4/0.15)
±1.5°C (0–375°C) / ±0.4% (375–1000°C)
Superior oxidation resistance vs Type K. No green-rot phenomenon. Longer service life in vacuum and inert atmospheres. Lower drift rate above 1000°C.
Slightly higher cost than Type K. Less established EMF reference data compared to Type K.
Technical Specifications
| Property | Specification |
|---|---|
| Diameter Range | φ0.025mm – φ5.0mm |
| Tolerance | ±0.005mm (fine) / ±0.02mm (standard) |
| Temperature Range | −270 … +1300 °C |
| Standards | IEC 60584-1 Class 1 / ASTM E230 / DIN EN 60584 |
| Surface Finish | Bright / Oxidised / Electro-polished |
| Packaging | DIN 125 spool / Coil / Custom reel |
| Coil Weight | 5kg / 10kg / 20kg standard |
| Traceability | Furnace batch number engraved on spool |
Available Product Forms
Bare Wire →
Solid single-strand, φ0.025–5.0 mm, bright or oxidised.
Stranded Wire →
Multi-strand for flexibility and vibration resistance. 7/19/37 strand.
How to specify Type N Thermocouple Wire
- Confirm the alloy for your operating temperature — Nicrosil / Nisil, rated −270 … +1300 °C.
- Check the atmosphere before ordering — Slightly higher cost than Type K. Less established EMF reference data compared to Type K.
- Choose the product form — Bare Wire or Stranded Wire. For Type N Thermocouple Wire the deciding factor is the service condition: superior oxidation resistance vs Type K. No green-rot phenomenon. Longer service life in vacuum and inert atmospheres. Lower drift rate above 1000°C.
- Fix the conductor diameter within φ0.025mm – φ5.0mm (±0.005mm (fine) / ±0.02mm (standard)).
- Quote against IEC 60584-1 Class 1 and request the MTC / EMF calibration certificate with the furnace batch number — state which Type N Thermocouple Wire form you need so the certificate scope matches the delivered conductor.
Frequently Asked Questions
How does Type N differ from Type K at high temperature?
The Nicrosil positive leg (NiCrSi 84.4/14.2/1.4) carries 1.4% silicon, which forms a protective SiO₂ layer and suppresses the chromium oxidation behind green rot. Type N drift stays within ±1 °C after 500 h at 1000 °C.
What temperature range does Type N cover?
−270 °C to +1300 °C, with EMF tolerance ±1.5 °C (0–375 °C) / ±0.4% (375–1000 °C) to IEC 60584-1 Class 1.
Where is Type N specified instead of Type K?
Vacuum furnaces, aerospace pyrometry to AMS 2750, gas turbine exhaust monitoring and semiconductor processes — anywhere sensor replacement is costly or long-interval drift matters.
What is the trade-off of choosing Type N?
A slightly higher cost than Type K and a smaller body of published EMF reference data. Both are supplied to the same standards, so instrumentation support is the main consideration.
Bottom line: Type N is the right choice above 1000 °C or wherever the atmosphere is vacuum or reducing: the 1.4% silicon in Nicrosil suppresses green rot and holds drift within ±1 °C after 500 h at 1000 °C. The premium over Type K is small and is normally recovered the first time an unplanned furnace shutdown is avoided.