Thermal instrumentation classification Which of the following is classified as a thermoelectric pyrometer (based on the Seebeck effect)?

Introduction / Context:
Temperature measurement technologies fall into several families: contact electrical (thermocouples and RTDs), non-contact radiative (optical and total radiation pyrometers), and expansion/pressure devices. Within these, “thermoelectric pyrometers” specifically exploit the Seebeck effect: a voltage is produced when two dissimilar metals form junctions at different temperatures.

Given Data / Assumptions:

• We compare common industrial sensors: thermocouple, RTD, optical pyrometer, radiation pyrometer.
• “Thermoelectric” implies direct conversion of temperature difference to EMF.
• No special wiring or compensation details are required to answer the classification.

Concept / Approach:
A thermocouple comprises two different metals; the EMF generated is approximately proportional to the temperature difference between the measurement and reference (cold) junctions. This is the canonical example of a thermoelectric pyrometer. An RTD uses resistance change with temperature, not EMF generation. Optical and radiation pyrometers infer temperature from spectral radiance and total radiant power, respectively, without contact or Seebeck-based EMF.

Step-by-Step Solution:

Verification / Alternative check:
Industrial standards classify thermocouples (Types K, J, T, etc.) as thermoelectric sensors; RTDs are resistive; optical/radiation devices are radiometric.

Why Other Options Are Wrong:

• RTD: Uses resistance change, requires current excitation.
• Optical / Radiation pyrometer: Measure emitted radiation; no contact EMF is generated.

Common Pitfalls:
Assuming all “pyrometers” are non-contact; historically, the term includes contact thermoelectric devices as well.

Final Answer:
Thermocouple