How accurate is a thermocouple?

The accuracy of a thermocouple will depend on a few factors such as the construction, the thermocouple alloy, sheath material and the temperature being measured and so thermocouples cannot be made to exactly match the published tables.

Thermocouple output tolerances for the thermocouple wires used in the manufacture of sensors are published in IEC 60584-1 and are shown in the table below:

Thermocouple Tolerances to IEC 60584-1

Thermocouple
Type		 Temperature Range and
Tolerance Value		 Tolerance Class
1 2 31
K Temperature Range -40°C to +375°C -40°C to +333°C -167°C to +40°C
Tolerance Value ±1.5°C ±2.5°C ±2.5°C
Temperature Range +375°C to +1000°C +333°C to +1200°C -200°C to -167°C
Tolerance Value ±0.004 . |t| ±0.0075 . |t| ±0.015 . |t|
T Temperature Range -40°C to +125°C -40°C to +133°C -67°C to +40°C
Tolerance Value ±0.5°C ±1°C ±1°C
Temperature Range +125°C to +350°C +133°C to +350°C -200°C to -67°C
Tolerance Value ±0.004 . |t| ±0.0075 . |t| ±0.015 . |t|
J Temperature Range -40°C to +375°C -40°C to +333°C -
Tolerance Value ±1.5°C ±2.5°C -
Temperature Range +375°C to +750°C +333°C to +750°C -
Tolerance Value ±0.004 . |t| ±0.0075 . |t| -
N Temperature Range -40°C to +375°C -40°C to +333°C -167°C to +40°C
Tolerance Value ±1.5°C ±2.5°C ±2.5°C
Temperature Range +375°C to +1000°C +333°C to +1200°C -200°C to -167°C
Tolerance Value ±0.004 . |t| ±0.0075 . |t| ±0.015 . |t|
R Temperature Range 0°C to +1100°C 0°C to +600°C -
Tolerance Value ±1°C ±1.5°C -
Temperature Range +1100°C to +1600°C +600°C to +1600°C -
Tolerance Value ±[1 + 0.003(t -1100)]°C ±0.0025 . it l -
S Temperature Range 0°C to +1100°C 0°C to +600°C -
Tolerance Value ±1°C ±1.5°C -
Temperature Range +1100°C to +1600°C +600°C to +1600°C -
Tolerance Value ±[1 + 0.003(t -1100)]°C ±0.0025 . it l -
How does a thermocouple work? What is the temperature range of a thermocouple? What is a thermocouple? Which type of junction should I choose?
       
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