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1. Today • Temperature transducers • International Temperature Scale • Classification and usage • Thermocouples • Thermistores • Resistance Temperature Detectors • Optical Temperature Transducers • Load Effect and mounting precautions

2. International Temperature Scale While other quantities of the SI are extensive, Temperature is an intensive quantity This makes the implementation of a reference temperature standard difficult… A 25 °C B 25 °C C 25 °C A 10kg B 10kg C 20kg

3. International Temperature Scale The SI defines as a primary quantity the thermodynamic temperature, defined by Lord Kelvin and based on a Carnot cycle on an ideal gas between two references. While a real gas can behave like an ideal one in a defined range, no gas has the same behaviour in the whole range of temperature required commonly, therefore a set of different practical standards were defined for different temperature ranges Absolute zero0 K = -273.15 °C Water triple point273.16 K = 0.01 °C

4. International Temperature Scale Actually the valid standard is the ITS-90, which defines the following ranges: • Between 0.65 K and 5.0 K: defined by the vapor-pressure temperature relationship of 3He and 4He. • Between 3.0 K and 24.5561 K (triple point of neon): helium gas thermometer calibrated at 3 fixed points. • Between 13.8033 K (triple point of hydrogen) and 1234.93 K (freezing point of silver): Standard Platinum resistance thermometer (RTD) calibrated at 12 fixed points. • Above 1234.93 K (freezing point of silver): ITS-90 is defined in terms of a defining fixed point and the Planck radiation law.

5. International Temperature Scale • Between the practical ITS and the absolute thermodynamic scale of the SI there are, actually, minor discrepancies, although the uncertainty arising from them is generally negligible with respect with the transducer overall accuracy. • Given the choice of a common reference interval (0°C – 100°C) an equivalence of 1°C=1 K interval can be used for practical reason • Other equivalences are given byT[K] =t [°C]+273.15=5/9T[°R]=5/9(t [°F]+459.69)kelvin=celsius=rankine=fahrenheit

6. Temperature Transducers • Thermal Expansion Thermometersbased on a mechanical deformation • Thermocouplesbased on the Seebek-Thomson effect • Resistance based Thermometersbased on the resistance-temperature relation • Optical Systemsbased on the Planck radiation law • Stellar Temperature Detectorsbased on gas kinetic theory

7. Thermocouples (TC) • Temperature transducers • International Temperature Scale • Classification and usage • Thermocouples • Thermistores • Resistance Temperature Detectors • Optical Temperature Transducers • Load Effect and mounting precautions

8. Thermistores • Temperature transducers • International Temperature Scale • Classification and usage • Thermocouples • Thermistores • Resistance Temperature Detectors • Optical Temperature Transducers • Load Effect and mounting precautions

9. Resistance Temperature Detector (RTD – Pt100) • Temperature transducers • International Temperature Scale • Classification and usage • Thermocouples • Thermistores • Resistance Temperature Detectors • Optical Temperature Transducers • Load Effect and mounting precautions

10. Optical Temperature Transducers • Temperature transducers • International Temperature Scale • Classification and usage • Thermocouples • Thermistores • Resistance Temperature Detectors • Optical Temperature Transducers • Load Effect and mounting precautions

11. Load Effect and mounting precautions • Temperature transducers • International Temperature Scale • Classification and usage • Thermocouples • Thermistores • Resistance Temperature Detectors • Optical Temperature Transducers • Load Effect and mounting precautions