| Thermocouple Wire Color Codes |
| Color codes have been adopted by various national and international standard agencies for identification of thermocouple wire and thermocouple products. In the United States, thermocouple-grade wire normally has a brown overall jacket. For Types B, R and S, the color codes relate to the compensating cable normally used. |
| Type |
United States
ANSI
96.1 |
United Kingdom
BS
1843 |
West Germany
DIN
43714 |
France
NF
C42-323 |
Japan
JIS
C1610-1981 |
| E |
| Purple |
 |
+ Purple |
| – Red |
|
| Brown |
| |
+ Brown |
| – Blue |
|
| Black |
| |
+ Red |
| – Black |
|
– |
| Purple |
| |
+ Red |
| – White |
|
| J |
| Black |
| |
+ White |
| – Red |
|
| Black |
| |
+ Yellow |
| – Blue |
|
| Blue |
| |
+ Red |
| – Blue |
|
| Black |
| |
+ Yellow |
| – Black |
|
| Yellow |
| |
+ Red |
| – White |
|
| K |
| Yellow |
| |
+ Yellow |
| – Red |
|
| Red |
| |
+ Brown |
| – Blue |
|
| Green |
| |
+ Red |
| – Green |
|
| Yellow |
| |
+ Yellow |
| – Purple |
|
| Blue |
| |
+ Red |
| – White |
|
| N |
| Orange |
| |
+ Orange |
| – Red |
|
– |
– |
– |
– |
| B |
| Grey |
| |
+ Grey |
| – Red |
|
– |
| Grey |
| |
+ Grey |
| – Red |
|
– |
| Grey |
| |
+ Red |
| – White |
|
| R |
| Green |
| |
+ Black |
| – Red |
|
| Green |
| |
+ White |
| – Blue |
|
– |
– |
| Black |
| |
+ Red |
| – White |
|
| S |
| Green |
| |
+ Black |
| – Red |
|
| Green |
| |
+ White |
| – Blue |
|
| White |
| |
+ Red |
| – White |
|
| Green |
| |
+ Yellow |
| – Green |
|
| Black |
| |
+ Red |
| – White |
|
| T |
| Blue |
| |
+ Blue |
| – Red |
|
| Blue |
| |
+ White |
| – Blue |
|
| Brown |
| |
+ Red |
| – Brown |
|
| Blue |
| |
+ Yellow |
| – Blue |
|
| Brown |
| |
+ Red |
| – White |
|
|
|
| Thermocouple Reference |
| Type |
J |
K |
T |
| Material |
Iron (+)
vs.
Constantan (-) |
Nickel (10%) Chromium (+)
vs.
Nickel (5%) Aluminum Silicon (-) |
Copper (+)
vs.
Constantan (-) |
| Temperature Range |
0°C to 760°C |
0°C to 1370°C |
-160°C to 400°C |
|
|
| Comparison of Temperature Transducers |
| Type |
Thermocouple |
RTD |
Thermistor |
| Advantages |
| • |
Self-powered |
| • |
Simple, rugged |
| • |
Lower cost |
| • |
Wide temperature range |
|
| • |
Most stable |
| • |
Most accurate |
| • |
Better linearity |
|
|
| Disadvantages |
| • |
Nonlinear |
| • |
Low voltage |
| • |
Least stable |
| • |
Least sensitive |
| • |
Reference required |
|
| • |
Expensive |
| • |
Current source required |
| • |
Small resistance change |
| • |
Low absolute resistance |
| • |
Self-heating |
|
| • |
Nonlinear |
| • |
Limited temperature range |
| • |
Fragile |
| • |
Current source required |
| • |
Self-heating |
|
|
|
| Time Contraints |
| The time constant of any sensor is defined as the time required for that sensor to respond to 63.2% of its total output signal when subjected to a step change. The step change can be either an increase or decrease in the parameter being measured. Five constants are required for a sensor to reach 99% of its total change. The graph to the right illustrates this relationship. |
 |
|
|
| Time Constant of Exposed Thermocouples |
 |
Time Constant as a Function of
Wire Size for Exposed Wire
Thermocouples in Air T=200°F |
|
|
| Radiation Error of Exposed Thermocouples |
 |
Radiation Error as a Function of
Wire Sizes for Thermocouples in
Air at 2000°F, at 1 Atmosphere
and Mach 0.3 |
|
|
|
|
