ABSTRACT

From the mV versus temperature plot in Figure 2.7, it might be interpreted that W-Re thermocouple wire would be a good choice (e.g. high output and high temperature), but it must be used in a reducing or inert atmosphere. For an oxidizing atmosphere, type B thermocouples are the most refractory, but they have a very low output at low temperatures, and show a temperature anomaly whereby a voltage reading could correspond to either of two temperatures (Figure 2.8). Thus, reading temperatures below "'100°C is not practical. One small advantage, however, is that room temperature compensation of this thermocouple type is practically negligible (e.g. the thermocouple output is -.002 m V at 25°C).