Jim Sulciner


HMI, OI February 1, 1999

Choosing RTDs and thermocouples

The two most common ways of measuring industrial temperatures are with resistance temperature detectors (RTDs) and thermocouples. But when should control engineers use a thermocouple and when should they use an RTD? The answer is usually determined by four factors: temperature, time, size, and overall accuracy requirements. What are the temperature requirements? If process temperatures fall from -328 to 932°F (-200 to 500°C), then an industrial RTD is an option. But for extremely high temperatures, a thermocouple may be the only choice. What are the time-response requirements? If the process requires a very fast response to temperature changes--fractions of a second as opposed to seconds (i.e.

By Jim Sulciner
All Articles