Why are thermowells used with RTDs?
A. Increase voltage
B. Protect terminals
C. Reduce wiring
D. Protect sensor
View Answer
Answer: D
Explanation:
A thermowell is a protective tube installed between the process and the RTD sensor. Its primary purpose is to protect the RTD from harsh process conditions while still allowing accurate temperature measurement.
Thermowells protect RTDs from:
High pressure
High flow velocity
Corrosive fluids
Mechanical damage
Process contamination
Additional Benefits
- Allows RTD removal without shutting down the process.
- Simplifies maintenance and sensor replacement.
- Extends sensor life in demanding industrial applications.
Why the Other Options Are Incorrect
- Increase voltage → RTDs operate by resistance measurement, not voltage generation.
- Protect terminals → Thermowells protect the sensing element, not electrical terminals.
- Reduce wiring → Thermowells have no effect on wiring requirements.
In industries such as oil & gas, power plants, chemical plants, and refineries, thermowells are widely used to ensure reliable and safe RTD operation.
Therefore, Option D (Protect sensor) is the correct answer.