1. Introduction to Temperature Measurement Nihal Gunasekara Sri Lanka Bangladesh BEST programme

2. Temperature and Scale What is temperature ? The first thermometer Types of scale Classification of thermometer International Temperature Scale 2 Bangladesh BEST Programme

3. What is temperature ? Ruler for the cool and hot ? – Motivation of the thermometer development The zeroth law of thermodynamics Temperature means the level of thermal energy. Driving force for the heat flow 3 ABC Thermal equilibrium Bangladesh BEST Programme

4. The first thermometer In 1594, G. Galileo – A type of gas thermometer – Volume change with temperature 4 Bangladesh BEST Programme

5. The First Glass Thermometer – In 1654, Ferdinand II, Grand Duke of Tuscany 5 Bangladesh BEST Programme

6. The first mercury thermometer – In 1706, Netherlands, Fahrenheit The first platinum resistance thermometer – In late 19 th century, Callendar The first commercial thermocouple – In 1885, Le Chatelier, Type S 6 Bangladesh BEST Programme History of Thermometry

7. Types of Scale  Fahrenheit ( o F) – In 1706, Netherlands, Fahrenheit In Europe, coldest day : 0 o F (= - 17.8 o C) Hottest day : 100 o F (= 37.8 o C) 0 o C = 32 o F 100 o C = 212 o F o F = 9/5 o C + 32 7 Bangladesh BEST Programme

8. degree Celsius ( o C) – In 1742, Sweden - A. Celsius Ice point : 0 o C Water boiling point : 100 o C Divided into 100 parts – Currently used together with international unit 8 Bangladesh BEST Programme Defining Temperature Scale

9. Absolute temperature - K ( thermodynamic temperature)  In 1848, Lord Kelvin  The second law of thermodynamics and Carnot heat engine  K = o C + 273.15  International unit of temperature scale 9 Bangladesh BEST Programme

10. History of International Temperature Scale  1927, The International Temperature Scale of 1927 (ITS-27)  1948, The ITS-48  1960, Amended edition of the ITS-48  1968, The International Practical Temperature Scale of 1968 (IPTS-68)  1976, Amended edition of the IPTS-68  1990, The ITS-90 10 Bangladesh BEST Programme

11. 11 International Temperature Scale of 1990 Bangladesh BEST programme

12. Triple Point of Water – Distilled water – De-ionized water – Air-free state – Water + Vapor + Ice – Reference of scale 12 Bangladesh BEST Programme

13. Equilibrium State Bangladesh BEST programme

14. Metal Fixed-Point 14 Bangladesh BEST Programme

15. NumberSubstancesState Defining temperature K oCoC 123456789123456789 He e-H 2 e-H 2 (He) Ne O 2 Ar Hg H 2 0 V T V(G) T 3 to 5 13.8033 ~17 ~20.3 24.5561 54.3584 83.8058 234.3156 273.16 -259.3467 -248.5939 -218.7916 -189.3442 -38.8344 0.01 15 Fixed-points Below 273.16 K Bangladesh BEST Programme

16. NumberSubstancesState Defining temperature K oCoC 9 10 11 12 13 14 15 16 17 H 2 0 Ga In Sn Zn Al Ag Au Cu TMFFFFFFFTMFFFFFFF 273.16 302.9146 429.7485 505.078 692.677 933.473 1234.93 1337.33 1357.77 0.01 29.7646 156.5985 231.928 419.527 660.323 961.78 1064.18 1084.62 16 Fixed-points Above 273.16 K Bangladesh BEST Programme

17. Defining Fixed Points of ITS -90 17 Bangladesh BEST Programme MaterialEquilibrium StateTemperature (K)Temperature (°C ) HydrogenTriple point13.8033-259.3467 Hydrogen (or He)Vapour pressure20.3-252.85 NeonTriple point24.5561-248.5939 OxygenTriple point54.3584-218.7916 ArgonTriple point83.8058-189.3442 Mercury (Hg)Triple point234.3156-38.8344 Water (H2O)Triple point273.160.01 Gallium (Ga)Melting point302.914629.7646 Indium (In)Freezing point429.7485156.5985 Tin (Sn)Freezing point505.078231.928 Zinc (Zn)Freezing point692.677419.527 Aluminum (Al)Freezing point933.473660.323 Silver (Ag)Freezing point1234.93961.78 Gold (Au)Freezing point1337.331064.18 Copper (Cu)Freezing point1357.771084.62

18. Different Types of Thermometers  Thermocouple thermometers  Resistance thermometers  Liquid-in-glass thermometers  Bimetallic thermometers  Radiation thermometers  Optical pyrometers 18 Bangladesh BEST Programme

19. Thermoelectric theory (Seebeck effect) In 1821, T.J.Seebeck found Hot Cold emf A B Cold A and B are two different metallic wires. Bangladesh BEST Programme

20. Practical Usage Measuring Instrument Measuring point Extension wires Reference junctions Thermocouple wires Bangladesh BEST Programme

21. Reference (cold ) Junction Accurate Measurements Ice Bath Modern TC Thermometers Compensation incorporated C J at a Constant Temp. Isothermal Block Bangladesh BEST Programme

22. Types and Materials 22 Type Materials Allowable environmentMax. operating temp. °C TCopper/Copper-nickel alloyOxidising, reducing, inert or vacuum370 JIron/copper-nickel alloyOxidising, reducing, inert or vacuum760 ENickel-chromium ally/copper- nickel alloy Oxidising or inert870 KNickel-chromium alloy/nickel aluminium alloy Oxidising or inert1260 NNickel-chromium-silicon alloy /nickel silicon-magnesium alloy Oxidising or inert1260 RPlatinum-13% rhodium alloy/paltinum Oxidising or inert1480 SPlatinum-10% rhodium alloy/platinum Oxidising or inert1480 BPlatinum-30% rhodium alloy/platinum- 6%rhodium alloy Oxidising or inert1700 Bangladesh BEST Programme

23. Resistance Thermometers  Platinum Resistance Thermometers (PRT)  Standard Platinum Resistance Thermometers (SPRT)  High Temperature Platinum Resistance Thermometers (HTPRT) 23 Bangladesh BEST Programme

24. Resistance Thermometers PRT Pt-100 100 Ω at 0 °C Working Standard SPRT 25 Ω at 0 °C Reference Standard HTPRT 2.5 Ω at 0 °C Reference Standard Available in the Range - 200 °C to 1000 °C 24 Bangladesh BEST Programme

25. Principle of Operation Change in Temperature of a Resistive Element Resistance Value Changed Platinum Element 25 Bangladesh BEST Programme

26. Terminal Configuration Red White Red Red White Pt -100/2 Pt – 100/3 Red Red White White Pt- 100/4 26 Bangladesh BEST Programme

27. Resistance Thermometers 27n Construction Thin Film PRT Long stem SPRT Reference SPRT PRT-100 Bangladesh BEST Programme

28. Liquid in Glass Thermometers Principle of Operation : Expansion of Liquid in a Glass Capillary Tube to Sense the Temperature Measuring Range : -20 °C to 600 °C 28 Bangladesh BEST Programme

29. Liquid in Glass Thermometers Condition of Immersion  Total Immersion Thermometers  Partial Immersion Thermometers  Complete Immersion Thermometers Measuring Range : -20 °C to 600 °C 29 Bangladesh BEST Programme

30. Liquid in Glass Thermometers 30 Bangladesh BEST Programme

31. Bimetallic Thermometers  Principle of Operation : Difference in the Thermal Expansion of Two Metals  Measuring Range : -100 °C to 540 °C  Accuracy : about 1% of reading 31 Bangladesh BEST Programme

32. Bimetallic Thermometers 32 Bangladesh BEST Programme

33. Radiation Thermometers Principle of Operation : As the temperature of the object increases more energy is emitted at progressively shorter wavelengths Measuring Range : 600 °C to 3500 °C Detectors : Mostly Silicon or Germanium 33 Bangladesh BEST Programme

34. Relationship Between Wavelength of the Emitted Radiation and Spectral Radiance 34 Bangladesh BEST Programme

35. Optical Pyrometers  Disappearing filament type  Constant radiation disappearing filament type  Automatic optical type 35 Bangladesh BEST Programme

36. Disappearing Filament Type Pyrometer 36 Bangladesh BEST Programme

37. Constant Radiation Disappearing Filament Type Pyrometer 37 Bangladesh BEST Programe

38. 38 Bangladesh BEST Programme