Both thermocouples and RTDs are useful sensors for determining process temperature. Thermocouples are generally less expensive than RTDs. They are more durable in high vibration or mechanical shock applications and are usable to higher temperatures. Thermocouples can be made smaller in size than most RTDs and they can be formed to fit a particular application.
Thermocouples are used in situations such as:
- Thermocouples are used when cost is an issue
- The thermocouple will be used in applications with temperatures in excess of 650°C
- Point, rather than area sensing, improves control
- The element will be used in high vibration or mechanical shock applications
RTDs provide higher accuracy than thermocouples in their temperature range because platinum is a more stable material than most thermocouple materials. RTDs also use standard instrumentation wire to connect to the measurement or control equipment, which has the ability to decrease the overall installation cost.
The ideal use of RTD's is in the following scenarios:
- RTD's are used when a high degree of standardisation is desirable
- Accuracy and stability are requirements of the customer’s specification
- RTD's are ideal for use when area, rather than point sensing, improves control
- Accuracy must extend over a wide temperature range
For more information regarding thermocouples and RTD's for temperature processing, visit Pyrosales .