Thermocouple Types
A comprehensive guide to standard thermocouple calibrations, ANSI color codes, and temperature ranges.
Chromel-Alumel
-200°C to +1260°C
-328°F to +2300°F
The most popular thermocouple in the world. Offers the widest usable temperature range, serving many industries from industrial furnaces to food service. Inexpensive, accurate, and reliable.
Food service, industrial furnaces, HVAC, automotive, oxidizing atmospheres.
Iron-Constantan
-40°C to +750°C
-40°F to +1382°F
The industrial workhorse. Widely used in legacy equipment and reducing atmospheres. However, the iron leg is susceptible to rust and corrosion, which can cause continuity problems and premature failure in moist or oxidizing environments.
Plastics, injection molding, inert materials, vacuum applications.
Copper-Constantan
-200°C to +350°C
-328°F to +662°F
The most accurate of the base-metal thermocouples. Exceptionally stable at sub-zero and cryogenic temperatures with excellent resistance to moisture and corrosion. Limited to a narrower temperature range than Types K or J.
Cryogenics, laboratory, food processing, environmental monitoring.
Chromel-Constantan
-200°C to +900°C
-328°F to +1652°F
Highest EMF output per degree of any standard thermocouple. Non-magnetic and excellent for cryogenic use.
Cryogenics, pharmaceutical, chemical plants.
Nicrosil-Nisil
-200°C to +1260°C
-328°F to +2300°F
Improved stability and oxidation resistance over Type K at high temperatures. Better long-term drift performance.
High temperature furnaces, gas turbines, engine exhaust.
Platinum-13% Rhodium / Platinum
0°C to +1480°C
+32°F to +2696°F
Noble metal thermocouple with excellent accuracy and stability. Slightly higher output than Type S. Used in precision applications.
Semiconductor manufacturing, glass production, calibration laboratories.
Platinum-10% Rhodium / Platinum
0°C to +1480°C
+32°F to +2696°F
Noble metal thermocouple historically used as the standard for calibrating the melting point of gold (1064.18°C). Very high accuracy.
Calibration standards, high-accuracy laboratory work, pharmaceutical.
Platinum-30% Rhodium / Platinum-6% Rhodium
+870°C to +1700°C
+1598°F to +3092°F
The highest temperature standard thermocouple. Unique in that both legs contain platinum-rhodium alloys. Very low output below 600°C.
Glass manufacturing, steel processing, ceramic kilns, high-temperature research.
Tungsten-Rhenium
0°C to +2320°C
+32°F to +4208°F
Designed for extreme temperatures in vacuum or inert atmospheres. Cannot be used in oxidizing environments as tungsten oxidizes rapidly above 300°C.
Vacuum furnaces, hydrogen atmospheres, sintering, aerospace research, nuclear applications.
Quick Reference Comparison
All standard thermocouple types at a glance. Temperature ranges, wire color codes, and typical accuracy per ASTM E230.
| Type | Alloys | Range (°C) | Range (°F) | ANSI Color | Standard Tolerance |
|---|---|---|---|---|---|
| K | Chromel / Alumel | -200 to +1260 | -328 to +2300 | Yellow | ±2.2°C or ±0.75% |
| J | Iron / Constantan | -40 to +750 | -40 to +1382 | Black | ±2.2°C or ±0.75% |
| T | Copper / Constantan | -200 to +350 | -328 to +662 | Blue | ±1.0°C or ±0.75% |
| E | Chromel / Constantan | -200 to +900 | -328 to +1652 | Purple | ±1.7°C or ±0.5% |
| N | Nicrosil / Nisil | -200 to +1260 | -328 to +2300 | Orange | ±2.2°C or ±0.75% |
| R | Pt-13%Rh / Pt | 0 to +1480 | +32 to +2696 | Green | ±1.5°C or ±0.25% |
| S | Pt-10%Rh / Pt | 0 to +1480 | +32 to +2696 | Green | ±1.5°C or ±0.25% |
| B | Pt-30%Rh / Pt-6%Rh | +870 to +1700 | +1598 to +3092 | Gray | ±0.5% above 870°C |
| C | W-5%Re / W-26%Re | 0 to +2320 | +32 to +4208 | Red | ±1% above 426°C |
Tolerances shown are "whichever is greater" per ASTM E230 / ANSI MC96.1. Special Limits of Error (SLE) offer approximately half these tolerances.
Thermocouple Wire Gauge Guide
Wire gauge affects maximum temperature rating, flexibility, and durability. Thicker wire lasts longer at high temperatures but is less flexible.
| AWG | Diameter | Max Temp (Type K) | Flexibility | Typical Use |
|---|---|---|---|---|
| 20 AWG | 0.032" | 1260°C / 2300°F | Stiff | Long runs, high temp, industrial |
| 24 AWG | 0.020" | 1093°C / 2000°F | Moderate | General purpose, most common |
| 28 AWG | 0.013" | 871°C / 1600°F | Flexible | Fast response, tight spaces |
| 30 AWG | 0.010" | 760°C / 1400°F | Very Flexible | Lab, sensors, fastest response |
Max temperatures are approximate and vary by insulation type. Thinner wire responds faster but has a shorter service life at high temperatures.
Not Sure Which Type You Need?
Selecting the wrong thermocouple type can lead to inaccurate readings and sensor failure. Our Thermal Advisors can help you choose the perfect sensor for your application.
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