Which metal is most commonly used in RTDs?
A. Zinc
B. Aluminum
C. Platinum
D. Tin
View Answer
Answer: C
Explanation:
Platinum is the most commonly used metal in industrial RTDs (Resistance Temperature Detectors) because of its excellent accuracy, stability, repeatability, and corrosion resistance.
The most popular RTDs are:
- Pt100 → 100 Ω at 0°C
- Pt1000 → 1000 Ω at 0°C
The “Pt” in Pt100 and Pt1000 stands for Platinum.
Why Platinum is Preferred
High accuracy
Excellent long-term stability
Wide operating temperature range
Good linearity
Resistant to oxidation and corrosion
Internationally standardized (IEC 60751)
Typical Platinum RTD Values
- 0°C → 100.0 Ω
- 100°C → 138.5 Ω
- 200°C → 175.9 Ω
Why the Other Options Are Incorrect
Zinc
- Not commonly used for RTD sensing elements.
Aluminum
- Poor long-term stability compared to platinum.
Tin
- Unsuitable for precision temperature measurement.
Because platinum provides the best combination of accuracy, stability, and reliability, Option C (Platinum) is the correct answer.