Thermocouples - Limit Deviation and Tolerances
Tolerances and limit deviation
The tolerances and limit deviations for thermocouples are defined in the DIN EN 60584 standard. In certain cases, the thermoelectric properties may deviate from the standardized reference values for thermoelectric voltages. Three classes (accuracy classes) are defined, which describe the permissible tolerances and limit deviations. See table.
Example for a Type K thermocouple “Class 1”:
The limit deviation, e.g., for a Type K thermocouple in Tolerance Class 1 is ±1.5°C or 0.40%.
In Tolerance Class 2, the limit deviation is ±2.5°C or 0.75%.
Additional tolerances and limit deviations for all common thermocouples, such as Type K, Type J, Type R, Type T, or Type S, are shown in the following table:
| Class 1 | Class 2 | Class 3 | ||||||
|---|---|---|---|---|---|---|---|---|
| Standard | Material | Temperature-range | *²Limit deviation | Temperature-range | *²Limit deviation | Temperature-range | *²Limit deviation | |
| type T | DIN EN 60584 | Cu-CuNi | -40 up to +350°C | ±0,5°C or 0,40% | -40 up to +350°C | ±1,0°C or 0,75% | -200 up to +40°C | ±1,0°C or 1,5% |
| type U *¹ | DIN 43710 | Cu-CuNi | - | - | 0 up to +600°C | ±3°C or 0,75% | - | - |
| type J | DIN EN 60584 | Fe-CuNi | -40 up to +750°C | ±1,5°C or 0,40% | -40 up to +750°C | ±2,5°C or 0,75% | - | - |
| type L *¹ | DIN 43710 | Fe-CuNi | - | - | 0 up to +900°C | ±3°C or 0,75% | - | - |
| type K | DIN EN 60584 | NiCr-Ni | -40 up to +1000°C | ±1,5°C or 0,40% | -40 up to +1200°C | ±2,5°C or 0,75% | -200 up to +40°C | ±2,5°C or 1,5% |
| type E | DIN EN 60584 | NiCr-CuNi | -40 up to +800°C | ±1,5°C or 0,40% | -40 up to +900°C | ±2,5°C or 0,75% | -200 up to +40°C | ±2,5°C or 1,5% |
| type N | DIN EN 60584 | NiCrSi-NiSi | -40 up to +1000°C | ±1,5°C or 0,40% | -40 up to +1200°C | ±2,5°C or 0,75% | -200 up to +40°C | ±2,5°C or 1,5% |
| type S | DIN EN 60584 | PtRh 10-Pt | 0 up to +1600°C | ±1,0°C or *³ | 0 up to +1600°C | ±1,5°C or 0,25% | - | - |
| type R | DIN EN 60584 | PtRh13-Pt | 0 up to +1600°C | ±1,0°C or *³ | 0 up to +1600°C | ±1,5°C or 0,25% | - | - |
| type B | DIN EN 60584 | PtRh30-PtRh6 | - | - | +600 up to +1700°C | ±1,5°C or 0,25% | +600 up to +1700°C | ±4,0°C or 0,5% |
Classes 1, 2, and 3 are valid for thermocouples
*¹ Since April 1994 the standard DIN 43710 is no longer valid.
*² For the limit deviation, the higher value is valid.
*³ 1°C or [1 + (t - 1100) x 0,003] °C
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