Type B thermocouple

Conductors (+ / −)

Pt-30 % Rh / Pt-6 % Rh

Range of the reference function

0 … 1820 °C

Sensitivity at 1200 °C

10.36 µV/°C

Class 1 tolerance

—

Class 2 tolerance

±1.5 °C or ±0.0025 × |t|, whichever is larger, 600 to 1700 °C

Class 3 tolerance

±4 °C or ±0.005 × |t|, whichever is larger, 600 to 1700 °C

Colours identify the type, not the quality of the cable. Older national codes (e.g. BS 1843, DIN 43714, JIS) used other colours; check before reusing existing cable.

Full type B EMF tableThermocouple calculator

Platinum-30 % rhodium against platinum-6 % rhodium, for the highest temperatures of the standard types: continuous use to about 1700 °C in glass, ceramics and high-temperature furnaces. The output is very low and almost zero below about 50 °C, so the cold junction usually needs no compensation and plain copper extension wire is common; for the same reason the type is not used below about 250 °C. With rhodium in both legs it resists grain growth and rhodium migration better than types R and S.