Although type B thermocouples have a specified theoretical range from 0 to 1820°C, there is uncertainty and calculations are problematic in the zone between 0 °C and 100 °C where the thermoelectric voltage fluctuates between -0.003 mV and +0.003 mV (0 to 50 °C) then increases very gradually up to 0.033 mV at 100 °C. In order to be able to make calculations with certainty to an accuracy of 1 °C in this zone, a means of measurement with a resolution of at least 0.01 µV for an accuracy of 0.1 µV would be required, but the ITS-90 table gives only an accuracy of 1 µV for type B. The standardised usage range is from +600 to +1700°C. The bottom limits for the calculations will therefore be 100 °C or 0.033 mV.
Type B thermocouples are commonly called: 18% thermocouples (explanation: 30% Rhodium (Positive) + 6% Rhodium (Negative) equals 36% divided by two gives 18%).
Our latest articles
Why is temperature not a physical quantity like other measurement units?
Temperature is not a quantity in the strict sense of the term as the majority of other measurement units are. A quantity is something which can be increased or decreased, for example length, area, power output, etc. Measuring a quantity…