Thermocouple Tolerances
Thermocouple Tolerances and Standards
In practice, thermocouples can’t always be made to conform exactly to the published tables. So thermocouple output tolerances for both noble and base metal thermocouples are published as IEC 60584-1, manufacturers providing the sensors to these agreed limits as shown in the table below.
The tolerance values are for thermocouples manufactured from wires normally in the diameter range 0.1 to 3mm, and do not allow for calibration drift during use. Thermocouples other than those listed in these standards are usually supplied with manufacturers’ batch tables.
Thermocouple Tolerances according to IEC 60584-1 (reference junction at 0ºC)
| 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| | |
| E | 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 +800°C | +333°C to +900°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 | - | |
| B | Temperature Range | - | - | +600°C to +800°C |
| Tolerance Value | - | - | +4°C | |
| Temperature Range | - | +600°C to +1700°C | +800°C to +1700°C | |
| Tolerance Value | - | ±0,0025 . |t| | ±0,005 . |t| | |
1) Thermocouple materials are normally supplied to meet the manufacturing tolerances specified in the table for temperatures above –40°C. These materials, however, may not fall within the manufacturing tolerances for low temperatures given under Class 3 for Types T, E, K and N. If thermocouples are required to meet limits of class 3, as well as those of Class 1 or 2 the purchaser shall state this, as selection of materials is usually required.
