Maximum temperature by thermocouple alloy
Operating range, tolerance and construction notes for all eight standardised thermocouple types side by side, from the −270 °C floor of Type N to the +1820 °C ceiling of Type B.
Types whose verified range covers the value are highlighted. Atmosphere is a separate check, a range alone does not qualify an alloy.
| Type | Family | Verified range | Tolerance | Sensitivity (µV/°C) | Relative cost |
|---|---|---|---|---|---|
| Type T | base | −200 … +350 °C | ±0.5 °C | 43 | Low |
| Type J | base | −40 … +750 °C | ±1.5 °C | 55 | Low |
| Type E | base | −200 … +900 °C | ±1.5 °C | 68 | Low-moderate |
| Type N | base | −270 … +1300 °C | ±1.5 °C | 39 | Moderate |
| Type K | base | −200 … +1370 °C | ±1.5 °C | 41 | Low |
| Type R | noble | 0 … +1768 °C (continuous ~1600) | ±1.0 °C | 10 | High |
| Type S | noble | 0 … +1768 °C (continuous ~1600) | ±1.0 °C | 10 | High |
| Type B | noble | 0 … +1820 °C (continuous ~1700) | ±0.5 °C | 6 | Highest |
A range is not a licence
The single most expensive mistake in alloy selection is reading the top of a range as a target. A Type K loop rated to 1370 °C will not survive long sitting near it in a dirty or oxygen-starved furnace. The range tells you where the pair is standardised; the atmosphere, the construction and the dwell time decide whether it will still be inside its tolerance band a month later.
Frequently Asked Questions (FAQ)
What is the maximum temperature for a Type K thermocouple?
Verified to +1370 °C, with the practical caution that between 800 °C and 1050 °C in low-oxygen or reducing service the Chromel leg oxidises selectively. That ceiling is a wire and construction figure, not a licence to sit near it continuously in every atmosphere.
When should I move from Type K to Type N?
When the process reaches above roughly 800 °C without free oxygen, or when long exposure above 1000 °C would drift a Type K reading out of specification. Type N is the alloy formulated for oxidising, vacuum and low-oxygen service in that band.
Why do Type R and Type S show a lower continuous figure than their range?
Because the top of their range is a short-term figure. The continuous-service number is lower, and that lower figure is the one to design to. The table shows both so the difference is not lost.
Are the noble-metal types worth the cost?
Only where the process genuinely needs them, clean oxidising service at the top of the range. Below roughly 1300 °C in a clean atmosphere a base-metal pair does the job at lower cost, and the platinum types are wasted there.
Working close to a ceiling?
Tell us the peak temperature, the atmosphere and how long the sensor sits there, we will confirm the alloy and the construction it needs.