Temperature Measurement: RTD or Thermocouple?

Temperature Measurement: RTD or Thermocouple?

Two most common temperature instruments used in process industry are RTD and thermocouple. To determine which one to use, the following should be considered:

RTD is preferred if one of the following aspects becomes a concern in measurement: Accuracy, Stability, Sensitivity and Linearity.
Thermocouple is preferred in application for high temperature measurement (more than 400 degC) or when exposed to shock or vibration.

This is the reason why projects usually specify RTD for most process temperature measurement, while thermocouple is applied in heater, flare or for vibration monitoring of compressor or pump.

Cost? It depends on the installation. Some panel or I/O card does not accept RTD directly so it requires a transmitter. On the other hand, extension wire would be an additional cost of thermocouple.