What is Thermocouple Tolerance Class?
Thermocouple tolerance class is the permitted deviation of a new thermocouple from its reference table, given by IEC 60584-1 as class 1, 2 or 3.
Thermocouple Tolerance Class Explained
Tolerance is the larger of a fixed value and a percentage of temperature. Class 1 is the tightest.
Tolerances apply to new wire. Ageing, contamination and inhomogeneity can add much larger errors in service.
Thermocouple Tolerance Class: Typical Values
| Type K or N, class 1 | ± 1.5 °C or ± 0.004 |t|, whichever is greater |
| Type K or N, class 2 | ± 2.5 °C or ± 0.0075 |t| |
| Type T, class 1 | ± 0.5 °C or ± 0.004 |t| |
Calculators for Thermocouple Tolerance Class
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Frequently Asked Questions
What is Thermocouple Tolerance Class?
Thermocouple tolerance class is the permitted deviation of a new thermocouple from its reference table, given by IEC 60584-1 as class 1, 2 or 3.
What is class 1 type K at 800 °C?
0.004 × 800 = 3.2 °C, which is larger than 1.5 °C, so ± 3.2 °C.
Are special limits the same as class 1?
They are similar ideas in ASTM E230, but the numbers differ slightly.
Learn more on the blog
Thermocouple calibration: 7 proven steps
A practical guide on instrumentationblog.in with more detail on thermocouple tolerance class and how it is applied on real plants.
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