Types J, K, T, E
Most common thermocouples for industrial and general-purpose applications. Inexpensive, widely available, suitable for temperatures up to 1300 °C. Different types optimized for specific temperature ranges and atmospheres.
| Type | Positive (+) | Negative (-) | Color (IEC) | Color (ANSI) | Range ( °C) | Notes |
|---|---|---|---|---|---|---|
| J | Iron (Fe) | Constantan (Cu-Ni) | White/Black | White/Red | -40 to 750 | Reducing atmospheres, oxidizes above 500 °C |
| K | Chromel (Ni-Cr) | Alumel (Ni-Al) | Green/White | Yellow/Red | -200 to 1250 | Most common, oxidizing atmospheres |
| T | Copper (Cu) | Constantan (Cu-Ni) | Brown/White | Blue/Red | -200 to 350 | Cryogenic to moderate, moist atmospheres |
| E | Chromel (Ni-Cr) | Constantan (Cu-Ni) | Violet/White | Purple/Red | -200 to 900 | Highest output (mV/ °C), oxidizing |
Types R, S, B
Platinum-based thermocouples for high-temperature applications. Excellent stability and accuracy but expensive. Used in laboratories, heat treatment, and high-temperature processes up to 1700 °C.
| Type | Positive (+) | Negative (-) | Color (IEC) | Color (ANSI) | Range ( °C) | Notes |
|---|---|---|---|---|---|---|
| R | Pt-13%Rh | Platinum (Pt) | Orange/White | Black/Red | 0 to 1450 | High accuracy, oxidizing/inert |
| S | Pt-10%Rh | Platinum (Pt) | Orange/White | Black/Red | 0 to 1450 | Similar to R, slightly lower output |
| B | Pt-30%Rh | Pt-6%Rh | Gray/White | Gray/Red | 200 to 1700 | Highest temperature, no cold junction needed |
Types N, C, D, G
Special-purpose thermocouples for extreme temperatures and harsh environments. Types N (Nicrosil-Nisil) as alternative to Type K. Tungsten-rhenium types (C, D, G) for vacuum/inert atmospheres up to 2300 °C.
| Type | Positive (+) | Negative (-) | Color (IEC) | Color (ANSI) | Range ( °C) | Notes |
|---|---|---|---|---|---|---|
| N | Nicrosil (Ni-Cr-Si) | Nisil (Ni-Si-Mg) | Pink/White | Orange/Red | -270 to 1250 | Type K replacement, better stability |
| C | W-5%Re | W-26%Re | - | Green/White | 0 to 2300 | Vacuum/inert only, very high temp |
| D | W-3%Re | W-25%Re | - | Green/White | 0 to 2300 | Similar to C, slightly different output |
| G | Tungsten (W) | W-26%Re | - | - | 0 to 2200 | Vacuum/hydrogen, extreme temp |
IEC 60584 vs ANSI MC96.1
Critical difference between IEC (international) and ANSI (US) color standards. IEC uses positive leg color + white; ANSI uses positive leg color + red negative. Mismatched colors cause reverse polarity and measurement errors.
| Type (Standard) | Positive (+) Color | Negative (-) Color | Notes |
|---|---|---|---|
| Type J (IEC) | Black | White | IEC 60584-3 standard |
| Type J (ANSI) | White | Red | ANSI MC96.1 standard |
| Type K (IEC) | Green | White | Most common internationally |
| Type K (ANSI) | Yellow | Red | US standard, different from IEC! |
| Type T (IEC) | Brown | White | Cryogenic applications |
| Type T (ANSI) | Blue | Red | US standard |
| Type E (IEC) | Violet | White | High sensitivity |
| Type E (ANSI) | Purple | Red | US standard |