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Module 2 Temperature, pressure and fluid velocity measurement

Sub module 2.1 to 2.7 (Temperature measurement) Quadrant 2 List of animations/Videos: Thermometers/ Thermocouples/ Thermopiles (Sub module 2.1, 2.2)

1. Compact thermometer production aspects are presented in this video http://www.endress.com/eh/home.nsf/contentview/30F48ECEB0E7E093C125761600359E4D?Open&popup

2. Calibration procedure of thermocouples are presented in this video http://www.endress.com/eh/home.nsf/contentview/E32D868E934D437EC1257616003578A2?Open&popup

3. Production details of temperature sensors are shown in this video http://www.endress.com/eh/home.nsf/contentview/6CF1FF4897B5DB11C12575D300371530?Open&popup

4. Thermal flow measuring principles are discussed in this video http://www.endress.com/eh/home.nsf/contentview/B576C8158E0E609CC12575D2004C7BF8?Open&popup)

5. www.chipdip.ru 6. http://in.video.search.yahoo.com/video/play;_ylt=A2oKiKUxMSxReXsAKHbmHAx.;_ylu=

X3oDMTBrc3VyamVwBHNlYwNzcgRzbGsDdmlkBHZ0aWQD?p=thermistors+video&vid=730c435730e3c86f88b262fd0d953c48&l=00%3A04&turl=http%3A%2F%2Fts4.mm.bing.net%2Fth%3Fid%3DV.4757776694902859%26pid%3D15.1&rurl=http%3A%2F%2Fwn.com%2Fthermistors&tit=Thermistors&c=0&sigr=10pq6fsdu& (thermistors)

7. http://www.youtube.com/watch?v=kq4r-jm3acA (Measuring Temp. using Thermocouple)

8. http://www.youtube.com/watch?v=hTQ_38xd_uE&NR=1&feature=endscreen ( fun with thermocouples)

9. http://www.youtube.com/watch?v=joaxrEquja8&feature=endscreen (thermocouple cabration)

10. http://www.youtube.com/watch?v=AubXDi6AD2M&feature=endscreen (thermocouple tutorial)

11. http://www.youtube.com/watch?v=JQUY_bs59a4 (copper and steel thermocouple) 12. http://www.youtube.com/watch?v=vCCc2-qYS2A (filled type , bimetallic type , RTD

thermometers )

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13. http://www.youtube.com/watch?v=gtO0kQ-PT_0&feature=player_detailpage (thermocouples)

14. http://www.youtube.com/watch?v=fMJSJjOwKII (temperature sensor technology) Resistance thermometry (sub-module 2.3)

15. Thermisters, thermocouples and RTDs are compared http://www.youtube.com/watch?feature=player_embedded&v=bhrjhE0PdQA#!

16. Animal shaped thermometers – pictures, price, specification details are available in this site : http://www.alibaba.com/showroom/resistance-thermometer-animations.html

Pyrometry (Sub-module 2.5) 17. 2-color pyrometer video presentation : www.youtube.com/watch?v=4P4xZ4WzzhI 18. pyrometers applications, product specifications are shown in this video

http://in.video.search.yahoo.com/video/play?p=pyrometer+video&tnr=21&vid=747d103f6e2db5b0f6ff609ee8c661c3&turl=http%3A%2F%2Fts2.mm.bing.net%2Fth%3Fid%3DU.4721574406127845%26pid%3D15.1&rurl=http%3A%2F%2Fwn.com%2Fpyrometer&sigr=10nlrl6vt&tt=s&tit=Pyrometer&back=http%3A%2F%2Fin.search.yahoo.com%2Fsearch%3Fei%3DUTF8%26p%3Dpyrometry%2Bvedio%26vm%3Dr%26rd%3Dr1%26fr%3Dush1-finance&sigb=12nspijct

19. http://www.pyrometer.com 20. Pyrometer working details are presented in this video

http://science.howstuffworks.com/dictionary/physics-terms/pyrometer-info.htm 21. Disappearing filament optical pyrometer tutorial and specifications are presented in

this video: http://www.spectrodyne.com/DFP2000/tutorial.asp Measurement of transient temperature (sub-module 2.6)

22. Transient temperature profile in a combustor is shown http://in.search.yahoo.com/search;_ylt=AoEYSEwb7O5_T21ndEZt4LjxULlG;_ylu=X3oDMTBoZXBvYzBnBHNlYwNVSCBTZWFyY2ggMTAw;_ylg=X3oDMTBzMDBjMGIwBGxhbmcDZW4tSU4EcHQDc2VjdGlvbnMEdGVzdAM-?p=transient+temperature+video&fr=ush1-finance

Surface temperature measurement (sub module 2.7)

23. Soldering iron wattage vs temperature variation is explained http://in.search.yahoo.com/search;_ylt=A2oKmLGjhzFS6X8AGgu7HAx.;_ylc=X1MyMTE0NzIzMDAzX3IyYmNrODczbGQzMThyZ2JwdiUyNmIlM0Q0JTI2ZCUzRHlENjltTnBwWUY0Rjg1d0NrdmdGb0JmNmR6ZkJCT2xHZUxGWGFFQS0lMjZzJTNENXYlMjZpJTNEcDU5cF9NTGM3ZWpvQlRHbjhKc1hjc3JjcHZpZHJQbUE1Mm9LaVhDRGpxMFlVYmd2UHdnTGNJWEFLbEl4aDZNQUNkMjlmcnVzaDEtZmluYW5jZWZyMnNiLXRvcGdwcmlkcXpTaENSY2VRVVNLUmdHNDBBTjh2QW5fcnNsdDEwbl9zdWdnMG9yaWdpbmluLnNlYXJjaC55YWhvby5jb21wb3MwcHFzdHJwcXN0cmxxc3RybDI5cXVlcnlob3Q

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gc3VyZmFjZSB0ZW1wZXJhdHVyZSB2aWRlb3Rfc3RtcDEzNzg5Nzc3NDE2ODh2dGVzdGlkSU5DMDAx?p=hot+surface+temperature+video&fr2=sb-top&fr=ush1-finance&vm=r&rd=r1

24. Thermowell for temperature sensing – machining on CNC machine is shown http://in.search.yahoo.com/search;_ylt=A2oKmLpskjFSZlAA90y7HAx.;_ylc=X1MyMTE0NzIzMDAzX3IyYmNrODczbGQzMThyZ2JwdiUyNmIlM0Q0JTI2ZCUzRHlENjltTnBwWUY0Rjg1d0NrdmdGb0JmNmR6ZkJCT2xHZUxGWGFFQS0lMjZzJTNENXYlMjZpJTNEcDU5cF9NTGM3ZWpvQlRHbjhKc1hjc3JjcHZpZGFrZUszV29LaVhDRGpxMFlVYmd2UHdvWGNJWEFLbEl4a213QURTOWlmcnVzaDEtZmluYW5jZWZyMnNiLXRvcGdwcmlkbWV3SU1IWDVUT0dEZm5oaVRUWGlQQW5fcnNsdDEwbl9zdWdnMG9yaWdpbmluLnNlYXJjaC55YWhvby5jb21wb3MwcHFzdHJwcXN0cmxxc3RybDM2cXVlcnl0aGVybW93ZWxsIHRlbXBlcmF0dXJlIHNlbnNpbmcgdmlkZW90X3N0bXAxMzc4OTgwODY3MTM2dnRlc3RpZElOQzAwMQ--?p=thermowell+temperature+sensing+video&fr2=sb-top&fr=ush1-finance&vm=r&rd=r1

25. Mini thermowell housing machining on CNC machine is shown http://in.search.yahoo.com/search;_ylt=A2oKmLpskjFSZlAA90y7HAx.;_ylc=X1MyMTE0NzIzMDAzX3IyYmNrODczbGQzMThyZ2JwdiUyNmIlM0Q0JTI2ZCUzRHlENjltTnBwWUY0Rjg1d0NrdmdGb0JmNmR6ZkJCT2xHZUxGWGFFQS0lMjZzJTNENXYlMjZpJTNEcDU5cF9NTGM3ZWpvQlRHbjhKc1hjc3JjcHZpZGFrZUszV29LaVhDRGpxMFlVYmd2UHdvWGNJWEFLbEl4a213QURTOWlmcnVzaDEtZmluYW5jZWZyMnNiLXRvcGdwcmlkbWV3SU1IWDVUT0dEZm5oaVRUWGlQQW5fcnNsdDEwbl9zdWdnMG9yaWdpbmluLnNlYXJjaC55YWhvby5jb21wb3MwcHFzdHJwcXN0cmxxc3RybDM2cXVlcnl0aGVybW93ZWxsIHRlbXBlcmF0dXJlIHNlbnNpbmcgdmlkZW90X3N0bXAxMzc4OTgwODY3MTM2dnRlc3RpZElOQzAwMQ--?p=thermowell+temperature+sensing+video&fr2=sb-top&fr=ush1-finance&vm=r&rd=r1

26. Thermowell machining on CNC machine http://in.search.yahoo.com/search;_ylt=A2oKmLpskjFSZlAA90y7HAx.;_ylc=X1MyMTE0NzIzMDAzX3IyYmNrODczbGQzMThyZ2JwdiUyNmIlM0Q0JTI2ZCUzRHlENjltTnBwWUY0Rjg1d0NrdmdGb0JmNmR6ZkJCT2xHZUxGWGFFQS0lMjZzJTNENXYlMjZpJTNEcDU5cF9NTGM3ZWpvQlRHbjhKc1hjc3JjcHZpZGFrZUszV29LaVhDRGpxMFlVYmd2UHdvWGNJWEFLbEl4a213QURTOWlmcnVzaDEtZmluYW5jZWZyMnNiLXRvcGdwcmlkbWV3SU1IWDVUT0dEZm5oaVRUWGlQQW5fcnNsdDEwbl9zdWdnMG9yaWdpbmluLnNlYXJjaC55YWhvby5jb21wb3MwcHFzdHJwcXN0cmxxc3RybDM2cXVlcnl0aGVybW93ZWxsIHRlbXBlcmF0dXJlIHNlbnNpbmcgdmlkZW90X3N0bXAxMzc4OTgwODY3MTM2dnRlc3RpZElOQzAwMQ--?p=thermowell+temperature+sensing+video&fr2=sb-top&fr=ush1-finance&vm=r&rd=r1

27. Types of thermowell available http://in.search.yahoo.com/search;_ylt=A2oKmJXikzFSA2kAvY.7HAx.;_ylc=X1MyMTE0NzIzMDAzX3IyYmNrODczbGQzMThyZ2JwdiUyNmIlM0Q0JTI2ZCUzRHlENjltTnBwWUY0Rjg1d0NrdmdGb0JmNmR6ZkJCT2xHZUxGWGFFQS0lMjZzJTNENXYlMjZpJTNEcDU5cF9NTGM3ZWpvQlRHbjhKc1hjc3JjcHZpZFZicERWbW9LaVhDRGpxMFlVYmd2UHdSV2NJWEFLbEl4ay5JQURBamxmcnVzaDEtZmluYW5jZWZyMnNiLXRvcGdwcmlkbl9yc2x0MTBuX3N1Z2cwb3JpZ2luaW4uc2VhcmNoLnlhaG9vLmNvbXBvczBwcXN0cnBxc3RybHFzdHJsMTZxdWVyeXRoZXJtb3dlbGwgdmlkZW90X3N0bXAxMzc4OTgxNTI4NDc3dnRlc3RpZElOQzAwMQ--?p=thermowell+video&fr2=sb-top&fr=ush1-finance&vm=r&rd=r1

28. Pioneer Thermowell Video shows different types of design ,types ,sizes, standards, materials ,dimensions and specification http://www.instrumentation-fittings.com/thermowell-vidoe.html

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Illustrations:

1. Wika bimetal thermometer drawing and technical information is provided http://www.dfs-gauges.com/products/75+TH2R+025+SS

2. Industrial thermowell drawing is provided http://www.dfs-gauges.com/products/3-4F2

List of questions (FAQ): Thermometers/ Thermocouples/ Thermopiles (Sub module 2.1, 2.2)

1. State the zeroth law of thermodynamics 2. Explain the principle of thermometry 3. What are isotherms? 4. List a few thermometric properties used to measure temperature. 5. Explain construction and working of a constant volume gas thermometer 6. Present gas thermometer characteristics 7. Explain ITS 90 8. Mention the secondary fixed points used in ITS 90 9. What are the properties used to make thermometers? 10. Explain Peltier effect with a neat sketch 11. Explain Thomson effect with a neat sketch 12. Explain Seebeck effect with a neat sketch 13. What are Kelvin relations? How they are interpreted? 14. Discuss the working principle of liquid-in-glass thermometers 15. What are the various types of pressure thermometers? Discuss the working principle of

any one with a neat sketch 16. What are thermocouples? 17. Sketch a basic thermocouple circuit and explain 18. Discuss a practical thermocouple circuit 19. Explain the working principle of thermocouples 20. Explain Setback effect 21. Discuss the construction of thermocouples 22. How thermocouples are protected? 23. List the commonly used thermocouples along with their working range. 24. State the laws of thermocouples 25. How the emf produced by thermocouple is measured? 26. What is ice point reference junction? How it is achieved?

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27. Sketch and explain an arrangement with many junctions with a single reference junction while measuring temperature at different points.

28. Discuss the practical aspects of thermoelectric thermometry. 29. What is reference junction of thermocouple? Why it is necessary? 30. Discuss an automatic cold junction compensation method 31. What are thermopiles? 32. Explain the importance of thermopiles. 33. With a neat schematic diagram explain its construction. 34. Mention the applications of thermopiles 35. What is swamping resistance?

Resistance thermometry (sub-module 2.3)

36. What is resistance thermometry? List the materials used in resistance thermometers. 37. Discuss a bridge circuit with lead wire compensation with three wire and

four wire arrangements. 38. Why there is self heating in RTDs? What is its effect on measurement?

Thermistors (sub-module 2.4)

39. What are thermisters? Mention its types with range of operation. 40. State the applications of thermisters 41. Compare resistance thermometers with thermistors 42. Explain the construction of bead-type thermistors. 43. Sketch the following types of thermistors: disc type, rod type, bead type. 44. Sketch a typical thermistor circuit for temperature measurement

Pyrometry (sub – module 2.5)

45. What is pyrometry? Explain 46. Explain the selective radiation pyrometry 47. Compare selective radiation pyrometer with total radiation pyrometer 48. List the various types of pyrometers. Discuss any one of them 49. Draw the schematic diagrams of the following to show constructional features

a. Optical pyrometer b. Thermopile c. Liquid filled pressure thermometer d. Vanishing filament pyrometer e. Thermocouple

50. What are the advantages of total radiation pyrometers? 51. Mention the applications of total radiation pyrometers? 52. Explain the partial radiation pyrometers

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53. Explain variable intensity comparison lamp method 54. Sketch and explain vanishing filament pyrometer. How the filament brightness is

adjusted? 55. Explain constant intensity comparison lamp method 56. What is bolometer? 57. Mention the transducers used for the following temperature measurements:

a. Oven temperature with a range of 0 to 1200 deg C b. Molten iron temperature c. Temperature in the range of -100 to 200 deg C d. Metal melting furnace with a range of 0 to 1200 deg C

58. Explain the working principle of optical pyrometer. 59. Explain the working principle of total-radiation pyrometer. 60. What is a cavity radiator? What is its use? Also, sketch a black body furnace. 61. With a schematic diagram, explain a two color pyrometer.

Transient temperature measurement (sub-module 2.6)

62. Explain the electrical analogy of temperature sensor as a first order system. 63. How transient temperatures are measured? Explain

Surface temperature measurement (sub module 2.7)

64. Explain the surface temperature measurement using a compensated probe 65. Explain the measurement of temperature within a solid 66. Explain how temperature of a moving fluid is measured. 67. Explain the sources of error in temperature measurement 68. Write a note on conduction error in thermocouple temperature measurement (explain

the lead wire and single wire models) 69. Discuss lead wire conduction analysis during temperature measurement of surface

exposed to a moving fluid 70. Write a note on errors in temperature measurement due to surface radiation 71. Write the assumptions made in thermometer well problem. 72. Present the analysis of thermometer well problem

Quadrant 3 Wiki links/reference links/courses from other university websites/case studies Thermometers/ Thermocouples/ Thermopiles (Sub module 2.1, 2.2)

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1. http://www.efunda.com/designstandards/sensors/thermocouples/thmcple_intro.cfm (common thermocouples )

2. http://en.wikipedia.org/wiki/Thermopile (thermopile) 3. http://www.omega.com/literature/transactions/volume1/glossary.html (thermopile) 4. http://www.eoc-inc.com/micro-

hybrid/Thermopile%20Properties%20&%20Applications%200609.pdf (contact@micro-hybrid.de (thermopile properties and applications)

5. http://www.azooptics.com/Article.aspx?ArticleID=288 (thermopile construction) 6. http://resource.invensys.com/instrumentation/specifications/pss/3/3_3c1a.pdf

(thermometer well specifications) 7. What is a temperature sensor? How to use a temperature sensor? How to measure

temperature? How to test a temperature sensor? Write some specifications of temperature sensor. http://www.instructables.com/id/Temperature-Sensor-Tutorial/

8. This site explains how to build temperature sensors with a voltage divide circuit and calibrate www.k12lab.com/lesson-plans/build-your-own-temperature-sensor

9. Some images of temperature sensor are presented in this site http://www.google.co.in/images?hl=en-IN&q=making+temperature+sensor&gbv=2&sa=X&oi=image_result_group&ei=kvgnUoGQN82XrAftk4HYDQ&ved=0CCoQsAQ

10. Thermocouple accuracy table, by type and temperature, is presented http://digital.ni.com/public.nsf/allkb/776AB03E065228408625727B00034E20

11. What is a thermocouple sensor? What are different thermocouple types? How to choose a thermocouple type? Which junction type to choose? What is response time? Thermocouple ranges and limits of error, thermocouple reference tables http://www.omega.com/prodinfo/thermocouples.html

12. What is thermocouple? Principle of thermocouple, derivation from Seebeck effect, practical use, voltage temperature relationship, cold junction compensation, grades, types, platinum types, chromel-gold/iron, aging of thermocouples, thermocouple comparison, applications, ….., thermocouple as vacuum gage. http://en.wikipedia.org/wiki/Thermocouple

13. How to make thermocouples? http://www.ehow.com/how_5003848_make-thermocouples.html

14. Images of Bayonet thermocouple are presented https://www.google.co.in/search?q=bayonet+thermocouple&tbm=isch&tbo=u&source=univ&sa=X&ei=B50pUuPLI-StiAeX4oHgAw&sqi=2&ved=0CDIQsAQ&biw=1280&bih=677

15. Bayonet thermocouple types are presented http://www.thermometricscorp.com/bayther.html

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16. Bayonet thermocouples- overview, description and documents and specifications http://www.instrumart.com/products/4746/spring-adjustable-bayonet-thermocouples

17. Types of measurement systems are briefly explained in this site : http://www.omega.com/prodinfo/temperaturemeasurement.html

18. Industrial temperature measurement – basics and practices are explained in detail: http://www05.abb.com/global/scot/scot211.nsf/veritydisplay/694c70d390bf18b2c1257490004d95b0/$file/03_temp-en-b-04_2011_secure.pdf

19. Temperature measurement – experimental procedure http://www.engr.uvic.ca/~mech455/Lab%204%20-%20Temperature%20Measurement.pdf

20. Practical guidelines for temperature measurement are presented http://www.omega.com/techref/measureguide.html

Resistance thermometry (Sub-module 2.3)

21. Basics of RTDs, element types, advantages and limitations, RTDs vs thermocouples, constructional details, wiring configurations, classifications of RTDs, applications and history, standard resistance thermometer data … http://en.wikipedia.org/wiki/Resistance_thermometer

22. Images of RTDs are presented https://www.google.co.in/search?q=rtd&tbm=isch&tbo=u&source=univ&sa=X&ei=lqkpUvD2BqnOiAfvuIGIDg&sqi=2&ved=0CEAQsAQ&biw=1280&bih=677

23. Introduction to RTD, benefits of RTDs, Types http://www.omega.com/prodinfo/rtd.html

24. Platinum resistance thermometer designs, specifications, special options and applications notes are presented: http://www.peaksensors.co.uk/products/resistance-thermometers/m-i-resistance-thermometer-insert-with-block/

25. Platinum resistance thermometer schematic diagram is presented : http://www.npl.co.uk/content/ConMediaFile/113

26. Calibration of standard long-stem platinum resistance thermometers (-196 deg C to 962 deg C ) procedure is explained in this site : http://www.google.co.in/imgres?imgurl=http://www.npl.co.uk/upload/img/standard-long-stem-platinum-resistance-thermometers-calibration.jpg&imgrefurl=http://www.npl.co.uk/temperature-humidity/products-services/calibration-of-standard-long-stem-platinum-resistance-thermometers&usg=__d9S6PzW20RSPw2zaiNQITBertY4=&h=300&w=400&sz=80&hl=en&start=31&zoom=1&tbnid=JCwjain02jL1gM:&tbnh=93&tbnw=124&ei=i0AwUpqcPInniAfMiIGoAQ&prev=/images%3Fq%3DPlatinum%2Bresistance%2Bthermometer%2Bvideo%26start%3D20%26sa%3DN%26hl%3Den-IN%26gbv%3D2%26tbm%3Disch&itbs=1&sa=X&ved=0CD8QrQMwCjgU

Thermistors (Sub-module 2.4)

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27. Thermistor basics, self heating, conduction model, thermistor symbol, applications are presented http://en.wikipedia.org/wiki/Thermistor

28. Introduction and types of thermistors are presented http://www.omega.com/prodinfo/thermistor.html

29. Tutorial on thermistor –practical precautions, linear thermistors http://www.princeton.edu/~cavalab/tutorials/public/Thermocouples.pdf

30. NTC thermistors, types, fabrication of bead type thermistor, NTC bead types, fabrications of surface electrode type thermistor, comparison of thermistor to other sensors, …. http://www.me.psu.edu/rahn/me462/ntcnotes.pdf

Pyrometry (sub-module 2.5) 31. Two color handheld infrared pyrometer specifications, manuals, pictures are displayed:

http://www.omega.com/pptst/OS3750.html 32. Detailed specifications of 2 color and single color handheld infrared pyrometer are

presented : http://www.omega.com/Temperature/pdf/OS3750.pdf 33. Pyrometer basics, operating principle, applications, references and good photographs

are presented : http://en.wikipedia.org/wiki/Pyrometer 34. Optical pyrometry- schematic diagram, working details, advantages, disadvantages and

applications are mentioned: http://www.instrumentationtoday.com/optical-pyrometer/2011/08/

Transient temperature measurement (sub-module 2.6) 35. Technical paper on ‘Transient temperature measurement using embedded

thermocouples, D.Rittel, Experimental Mechanics , June 1998, Volume 38, Issue 2, pp 73-78,

36. Technical paper on ‘Transient temperature measurements in a convectively cooled droplet, C. D. Richards, R. F. Richards, Experiments in Fluids ,October 1998, Volume 25, Issue 5-6, pp 392-400

37. Transient temperature measurement errors, are discussed in this paper by Keltner, Sandia national laboratories, http://www.fire.tc.faa.gov/pdf/fsr-0104.pdf

38. Technical paper on ‘Transient temperature measurement using embedded thermocouples’, D. Rittel : http://rittel.net.technion.ac.il/files/2012/12/transient.pdf

Systematic errors in temperature measurement (sub module 2.7) 39. Surface temperature sensors details are available in this site

http://www.campbellsci.com/surface-temperature 40. Non-contact temperature measurement on metal surfaces via infrared

http://www.optris.com/temperature-measurement-metal

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41. Surface temperature measurement thermocouples- swivel tip thermocouple and band type surface thermocouple are explained : http://marlinmfg.com/products/sensors/sufTempMeas.html

42. Thermowell mechanical application considerations are presented in this site: http://marlinmfg.com/pdfs/Catalog%20pdfs/Thermowells/complete/General%20Information%20complete.pdf

43. Thermowell basics, material and construction and flow forces acting on thermowell are presented: http://en.wikipedia.org/wiki/Thermowell

44. Thermowell images are presented : http://in.images.search.yahoo.com/search/images?_adv_prop=image&fr=ush1-finance&va=thermowell+temperature+sensor

45. Thermowell types commercially available are listed : http://www.pyromation.com/Products/Thermowells.aspx

Quadrant 4

Numerical problems: Problem on liquid in glass thermometer:

1. A liquid in glass thermometer is constructed with a bulb having a volume of 250 mm3. The capillary has a bore of 0.25 mm. The bulb is filled with Benzene which has a β = 1.24 x 10-3 /oC. Determine the sensitivity of this thermometer. The thermal expansion of glass is 2.76x10-5 /oC. Solution: Thermal expansion coeff of Benzene = βB = 1.24 x10-3 /oC Thermal expansion coeff of glass = βg = 0.027 x 10-3 /oC Capillary diameter = D = 0.25 mm Capillary area = Ac = 0.049 mm2 Bulb volume = V = 250 mm3 Relative thermal expansion = βrel = βB - βg = 1.213 x 10-3 /oC Change in volume of Benzene = ∆V = βrel xV = 0.303 mm3 /oC Sensitivity of thermometer = ∆L = ∆V/ Ac = 6.2 mm /oC

Problem on bimetal strip thermometer: 2. A bimetal strip thermometer is constructed using strips of nickel-chrome iron alloy

and invar bonded at 25 oC. The strips are 40 mm long and each 0.5 mm thick. Determine the (i) radius of curvature produced when thermometer is subjected to a temperature of 150 oC. (ii) deflection of free end in a perpendicular direction from initial line. αA = 12.5x10-6/ oC , EA = 1.5x10-6 kgf/cm2 = 150 GPa (Ni-Cr-iron alloy); αB = 1.7x10-6/ oC, EB = 2.2 x10-6 kgf/cm2 = 220 GPa (Invar) Solution: T = temperature = 150 oC

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δ = movement of free end =? tA = tB = thickness of strips = 0.5 mm L = length of strip = 40 mm to = Reference temperature = 25 oC

Ratios : rδ = tB / tA = 0.5/0.5 =1 rE = EB / EA = 220/150 = 1.466

(i) Radius of curvature: R = (tA + tB )�3(1 + r δ)2 + (1 + rδ x rE)( rδ2 + 1

rδx rE)� ÷ [6(αA− αB)(t− to)(1 + rδ)2 ]

After substitution and simplification, R=498.39 mm (ii) Deflection of tip = δ = R(1-cosφ) = R(1-cos(L/R)) = 498.39(1-cos4.58o) =

1.59 mm

3. A bimetallic strip is constructed of strips of yellow brass and invar bonded at 28 oC. Each strip has a thickness of 0.25 mm. Calculate the radius of curvature when a 50 mm long strip is subjected to a temperature of 125 oC. Also find deflection of tip of strip . Coeff. Of thermal expansion for yellow brass is 2.02x10-5 / oC and for invar is 1.7x10-6 / oC. Young’s modulus for yellow brass is 96.5 GPa and for invar is 147 GPa. Solution: Use the procedure given in problem 2. Answer: Radius of curvature = R = 188.1 mm Angle subtended = φ = 0.266 radians = 15.23o Deflection of tip = δ = R(1-cosφ) = 6.6 mm

Problem on Bourdon tube thermometer: 4. A Bourdon tube thermometer has a range of 0oC to 300oC, and produces a

corresponding rotation of 0 to 300o . Determine the sensitivity of the Bourdon tube in radians / oC, if the mechanical amplification is 30. Solution: Mechanical amplification = pointer rotation/angular displacement of tube Angular displacement of tube = 300/30 = 10o = 0.174 radians Sensitivity of Bourdon tube = angular displacement/temperature range = 0.174/300 = 0.00058 rad/ oC

Problems on thermocouples: 5. The hot junction of a chromel-alumel thermocouple is connected to a potentiometer

whose terminals are maintained at 24oC. the potentiometer reads 25.66 mV. Determine the temperature of the thermocouple junction? The thermocouple conforms to the following values which are based on reference junction at 0o C : Temp. o C 20 24 28 … 470 480 490 Voltage, mV 0.79 0.95 1.13 … 26.3 26.61 27

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Solution: From the law of intermediate temperatures, ( Em – Eo ) = (Em – Er ) + ( Er – Eo) where suffix m, r and o refer to the thermocouple hot junction, potentiometer reference terminal and the standard reference junction at 0o C. Measured emf = (Em – Er ) = 25.66 mV emf at 24 oC = ( Er – Eo) = 0.95 mV (given) So, emf based on 0o C reference temperature is ( Em – Eo ) = 25.66+0.95 = 26.61 mV. From the given table, for 26.61 mV, the temperature of hot junction is 480 oC.

6. An iron-constantan thermocouple is connected to a potentiometer whose terminals are at 50 oC. The potentiometer reading is 5.45 mV. Find the temperature of the thermocouple junction, using the following table: Table: Thermal emf in absolute mV (Ref. junction of 0o C) for Iron-constantan (J) Temperature oC 0 25 50 75 100 150 Potentiometer reading,mV 0 1.277 2.585 3.918 5.269 8.0 Solution: Thermoelectric potential corresponding to 50 oC from the above table is E50 = 2.585 mV The emf based on a 0o C reference temperature is ET = E50 + potentiometer reading ET = 2.585 +5.45 = 8.035 mV Temperature of the thermocouple junction corresponding to 8.035 mV is 150 oC (from the given table)

7. A K type thermocouple is used with a reference junction maintained at the ice point. The voltmeter connected with the thermocouple is showing 5.328 mV. Find the temperature in oC at the hot junction, using the ITS 90 table for K thermocouple given below. Temperature in oC 25 50 75 100 150 200 300

emf in absolute mV 1 2.023 3.059 4.096 6.138 8.139 12.209 Solution: From the above table, the hot junction temperature is found to be 130 oC

Problem on thermistor: 8. For a certain thermistor the Ro = 1000 Ω at 27o C, and the corresponding β = 3130.

Find the temperatures when the thermistor resistanes in Ω are (i) 2300, (ii) 2500 and (iii) 2700. Draw the scatter diagram – resistance Vs temperature. Solution: Given Ro = 1000 Ω To = 27 + 273 = 300 oK β = 3130 RT = 2300, 2500 and 2700 Ω

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Using the relationship, RT = Ro𝑒β �1T − 1To� (i) At RT = 2300 , T = 278 oK (ii) At RT = 2500 , T = 276 oK (iii) At RT = 2700 , T = 274 oK Scatter diagram: Temperature (y-axis) Vs Resistance (x-axis)

Problem on emissivity:

9. The brightness temperature of an object given by a vanishing filament pyrometer is 860 oC. A thermocouple used to measure the temperature of the object shows 1100 o C. determine the emissivity of the surface of the object, if the pyrometer has a λ=0.66 µm. Assume C2 = 14380 µm.K. Solution: Given TB = brightness temperature = 860 + 273 = 1133 oK Ta = object temperature = 1100 + 273 = 1373 oK λ = effective wavelength for the pyrometer = 0.66 µm

Target emissivity = ε λ = 𝑒 ��C2 λ�( 1Ta − 1

TB )� After substitution and computation we get, ε λ = 0.0347

Multiple choice questions (Choose the correct answer) 1. A RTD is

a. a active transducer b. a passive transducer c. an inductive transducer

278

276

274

273.5

274

274.5

275

275.5

276

276.5

277

277.5

278

278.5

2200 2300 2400 2500 2600 2700 2800

Series1

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d. a capacitive transducer

2. Compared with a thermister, the RTD is a. Less sensitive but more stable b. more sensitive but less stable c. Less sensitive and less stable d. more sensitive and more stable

3. In a three wire RTD bridge

a. One lead each is in the two adjacent arms and a third lead goes to detector

b. One lead each is in the two opposite arms and the third lead goes to the detector

c. One lead is in the RTD arm, while the other two go to the source and the detector respectively

d. None of the above

4. The metal normally used in a RTD is a.Copper b. Iron c. Platinum d. Silver

5. A thermister is inherently suitable for temperature measurements involving a. High span but low sensitivity b. high span and high sensitivity c. Low span but high sensitivity

6. A thermocouple is

a. Two similar metals joined together b. Two dissimilar metals joined together c. Two wire wound resistors joined together d. Two inductive coils joined together

7. A transducer suitable for high temperature and fast response time is called a

a. Thermistor b. RTD c. Thermocouple d. Resistance thermometer

8. For high temperatures, nearing 1550 deg C, the suitable thermocouple is a. Copper/constantan b. iron/constantan c. Chromel/constantan d. platinum/platinum/rhodium

9. For measuring temperature in the range of 1200 deg C to 3200 deg C we use:

a. RTD b. thermocouple c. thermistor d. total radiation pyrometer

10. The parameter of a semiconductor diode sensitive to temperature, is a. Forward voltage drop b. reverse voltage drop c. forward saturation current

11. The following should be incorporated in an RTD, to make the sensor most

sensitive a. Platinum b. nickel c. copper d. thermistor

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12. In a thermocouple , heat energy transferred to the hot junction is converted into

electrical energy by the following effect a. Johnson’s effect b. Seebeck effect c. Hall effect d. Piezoelectric effect

13. A thermocouple is needed to measure temperature in the range of 2000 to 2800

deg C. Suggest the suitable material a. Copper/constantan b. chromel /constantan c. iron/constantan d. tungsten/tungsten/rhenium

14. Using parallel combination of thermocouples it is possible to measure a. Small temperature differences between the two points b. Large temperature differences between the two points c. Average temperature of a number of points on the heated surface d. None of the above

15. Which one of the following is capable to measure the temperature of an object which is

either moving or idle a. Thermister b. thermocouple c. total radiation pyrometer d. Filled-in-system thermometer

16. Type J thermocouple has the following pair of wires joined together a. Iron/constantan b. copper/constantan c. chromel/constantan d. chromel/alumel

17. Type T thermocouple is suitable for temperature measurement in the range of – deg C a. -270 to 400 b. -50 to 1750 c. -270 to 1000 d. -270 to 1350 Answer Table

1.b 2. a 3. a 4. c 5. c 6. b 7. c

8. d 9. d 10. a 11. a 12. b 13. b 14. c

15. c 16. a 17.a

Pyrometer 18. In pyrometer the function of optical system is to focus the ----- onto the detector

e. Electromagnetic radiation b. thermal radiation c. nuclear fusion d. gamma ray

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19. A pyrometer is a non-contacting device that measures a. Electromagnetic radiation b. thermal radiation c. nuclear fusion d. gamma ray

20. Total radiation pyrometers are used to measure temperature in the range of --- deg C

a. 0 t 600 b. 1200 to 3500 c. 0 to 300 d. 3500 to 5000

21. Temperature range of radiation pyrometers is (in deg C) a. 0-500 b. 500-1000 c. -250 to 500 d. 1200 to 2500

Answer Table 18.b 19.b 20.b 21.d

Fill in the blanks with appropriate word/s 22. The most widely used metal for a RTD is ----- due to its high stability and wider --- range. 23. ----- wire is used as the sensing element in a RTD 24. Thermocouples in series or parallel are termed as ------- 25. A thermocouple consists of two ------ metals joined together 26. Temperature measurement using a thermocouple is based on the ------effect 27. Pyrometers measure the --------- emitted by a hot object 28. Most commonly used optical pyrometer is the-------- pyrometer 29. If the temperature of optical pyrometer filament equals that of the hot object, then the

filament ----- against the hot object 30. The basic principle of thermocouples is based on the --- effect 31. A -------is a device that converts one form of energy into another form

Answer Table

22.platinum, working 23.platinum 24. thermopile 25. dissimilar 26. Seebeck 27. thermal radiation 28. disappearing filament 29. vanishes 30. Seebeck 31. transducer

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True/false 32. Filled type thermometers are active transducers 33. Filters are used in optical pyrometers 34. Output of thermocouple can be measured by potentiometer circuit 35. Optical pyrometers function on the principle of light 36. Pyrometers work on the principle of thermal radiation 37. Platinum and copper are normally used in the construction of RTDs 38. Radiation pyrometers have high speed of response 39. Thermal response of thermistor is fast 40. Thermocouples are inexpensive than resistance thermometers 41. Bimetallic elements are used in high-frequency measurement applications

Answer Table

32. T 33. T 34. T 35. T 36. T 37. T 38. T 39. T 40. T 41. F

Assignment questions and solutions: Thermometers/ Thermocouples/ Thermopiles (Sub-module 2.1, 2.2) 1. List several thermometers used in practice and also thermometric property as well as

the symbol used to indicate it Ans:

Thermometer Thermometric property Symbol

Gas thermometer at constant volume

Pressure P

Electric resistance thermometer under constant tension

Electrical resistance R

Thermocouple Thermal electromotive force E Saturated vapor of a pure substance

Pressure P

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Blackbody radiation Spectral emissive power Acoustic thermometer Speed of sound a

2. What is a reference junction in thermocouple? Ans: When a thermocouple is used to measure temperature, one of its two junctions is

placed on the object whose temperature is to be measured. The voltage across the output terminals of the thermocouple depends upon the temperature at both junctions. This means that the temperature at the second junction must be either known or controlled to at least the accuracy expected from the measurement. This second junction is generally known as the reference junction

3. Mention a few applications of bayonet thermocouples

Ans: 1. Air-conditioning and refrigeration systems 2. Chemical and petrochemical industries 3. Energy and power plant technology 4. Machinery, plant and tank measurement 5. Oil and gas industries 6. Pipeline control 7. Plastics and rubber industries 8. Power and utilities 9. Pulp and paper 10. Water and wastewater treatment

4. What are advantages and limitations of common thermocouples Ans: Advantages: 1.Compact units, hence mounting is easy 2. Strong and low cost construction, they can withstand rough handling 3. No moving parts 4. Reasonably good dynamic response 5. Reasonable repeatability and good accuracy (+/- 0.2 to +/- 0.75% of fsd) 6. Output in the form of electrical signals, hence signals can be transmitted over a reasonable distance 7. Wide range of temperature (-200 to 3000 deg C) 8. Output signal is independent of wire size 9. Good stability for a long period of time Limitations: 1. Insulation needed while using in conducting fluids 2. Output signal requires amplification

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3. Less sensitive, normally 50 microV/deg C or less 4. Requires a well-known temperature reference normally ice water 5. Non-linearity exists, hence calibration curves are needed

Resistance thermometry (Sub-module 2.3)

5. What is basis for resistance thermometry? Ans: The change in resistance of some materials, which varies in a repeatable manner with temperature, is the basis of this measurement method. The materials in use generally fall in two categories: conductors and semiconductors. In general, the resistance of the highly conducting materials increases with increase in temperature. Whereas, the resistance of semiconductor materials generally (not always) decreases with increase in temperature.

6. Mention the normally used materials in the construction of resistance thermometers Ans: Materials used: Metals such as platinum, copper, tungsten, silver and nickel are used to fabricate resistance thermometers. Resistance thermometers may also be fabricated by depositing the thin films of platinum, nickel or copper on a ceramic substrate. Semiconducting materials such as oxides of copper, manganese, nickel, cobalt, lithium and titanium are used to make resistance thermometers (known as thermistors)

Thermistors( Sub-module 2.4) 7. What are thermistors? Mention the different types of thermistors .

Ans: Thermistor is a thermally sensitive variable resistor prepared by ceramic semiconducting materials. They are used to measure temperature. These are available in different shapes and sizes. Types: Small bead type, thin disc type, thin wafer type, rod type.

Sub-module 2.5 (Pyrometer) 8. Present the approximate values of temperature for different colors (colour scale) used in

optical pyrometry. b. Dark red (540 deg C) c. Medium cherry red (680 deg C) d. Orange (900 deg C)

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e. Yellow (1010 deg C) f. White (1205 deg C)

9. Mention a few applications of pyrometers Ans: Pyrometers are used in the following situations:

1. Reliable and continuous measurement of the melt temperature for effective control of the operation.

2. At very high working temperatures, with intense heat transfer between the molten salt and the steel being treated, precision is maintained by measuring the temperature of the molten salt.

3. A steam boiler may be fitted with a pyrometer to measure the steam temperature in the super heater

4. A hot air balloon is equipped with a pyrometer for measuring the temperature at the top of the envelope in order to prevent overheating of the fabric.

5. Used to measure temperatures of liquid metals or highly heated materials. 6. Can be used to measure furnace temperatures.

Systematic errors in temperature measurement (sub module 2.7)

10. Discuss the temperature measurement in solids and in moving fluid. Ans: Measurement of temperature within a solid: A hole is drilled in the solid whose temperature is to be measured. The thermocouple junction is fixed at the bottom of a blind hole made in the solid. The clearance between the thermocouple lead wire and hole is filled with a heat conducting material. The lead wire is exposed to the ambient as it comes out the hole. The lead wire conduction must be compensated by heat conduction into the junction from within the solid. Hence, it is expected that the solid temperature to be greater than the junction temperature (this is the temperature that is indicated) which is greater than the ambient temperature. Measurement of temperature of a moving fluid: Sometimes it is necessary to measure the temperature of a fluid flowing through a pipe. To prevent leakage of the fluid and to prevent direct contact between the fluid and the thermal sensor, a thermometer well is made. The sensor is fixed to the bottom of the well. The indicated temperature is the temperature of bottom the well (which is assumed to be similar to the moving fluid temperature due to heat conduction between the fluid and the duct wall). For schematic diagrams please refer web resource nptel.iitm.ac.in/courses/IIT-MADRAS/Mechanical_Measurements (sub module 2.7)

Self answered questions and answers:

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1. Discuss briefly with necessary diagrams Peltier effect, Thomson effect and Seebeck effect.

Ans: Visit website nptel.iitm.ac.in/courses/IIT-MADRAS/ Mechanical_Measurements (sub-module 2.2)

2. Sketch and explain a basic thermocouple circuit Ans: Visit website nptel.iitm.ac.in/courses/IIT-MADRAS/ Mechanical_Measurements (sub-module 2.2)

3. Discuss a practical thermocouple circuit

Ans: Visit website nptel.iitm.ac.in/courses/IIT-MADRAS/ Mechanical_Measurements (sub-module 2.2)

4. Explain the laws of thermoelectric circuits

Ans: Visit website nptel.iitm.ac.in/courses/IIT-MADRAS/ Mechanical_Measurements (sub-module 2.2)

5. Write a list of common thermocouple materials Ans: Visit website nptel.iitm.ac.in/courses/IIT-MADRAS/ Mechanical_Measurements

(sub-module 2.2, table 4)

6. Mention the standard thermocouple types Ans: Visit website nptel.iitm.ac.in/courses/IIT-MADRAS/ Mechanical_Measurements

(sub-module 2.2, table 5)

7. Mention the accuracy and range values of some thermocouple sensors Ans: Visit website nptel.iitm.ac.in/courses/IIT-MADRAS/ Mechanical_Measurements

(sub-module 2.2, table 7). Also refer : http://www.omega.com/prodinfo/thermocouples.html

8. How is insulation achieved in thermocouples? List some insulation materials

Ans: Visit website nptel.iitm.ac.in/courses/IIT-MADRAS/ Mechanical_Measurements (sub-module 2.2, table 8 and 9).

9. How are thermocouple junctions formed? Illustrate the various types of thermocouple junctions.

Ans: Visit website nptel.iitm.ac.in/courses/IIT-MADRAS/ Mechanical_Measurements (sub-module 2.2, Fig.17,18). Also refer: http://in.images.search.yahoo.com/search/images?_adv_prop=image&fr=yfp-t 704&va=thermocouple+junctions and

http://www.ehow.com/list_7598326_thermocouple-junction-types.html

10. Illustrate Bayonet or pencil type of thermocouple probe

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Ans: Visit website nptel.iitm.ac.in/courses/IIT-MADRAS/ Mechanical_Measurements (sub-module 2.2, Fig.19) also refer

http://www.wika.co.in/upload/BR_TC53_en_us_18312.pdf

11. Explain the thermocouple arrangements in series and parallel Ans: Visit website nptel.iitm.ac.in/courses/IIT-MADRAS/ Mechanical_Measurements

(sub-module 2.2, Fig.20,21,22 and 23).

12. Discuss a typical platinum resistance thermometer (PRT) with three wire arrangement Ans: Visit website nptel.iitm.ac.in/courses/IIT-MADRAS/ Mechanical_Measurements (sub-module 2.3, Fig.25).

13. Derive Callendar equation using usual notations. Also show a typical plot of Callendar correction as a function of the platinum resistance temperature

Ans: Visit website nptel.iitm.ac.in/courses/IIT-MADRAS/ Mechanical_Measurements (sub-module 2.3, Fig.26).

14. Discuss a bridge circuit with lead wire compensation with three wire and four wire arrangement.

Ans: Visit website nptel.iitm.ac.in/courses/IIT-MADRAS/ Mechanical_Measurements (sub-module 2.3, Fig.27, 28).

15. Sketch different types of thermistors

Ans: : Visit website nptel.iitm.ac.in/courses/IIT-MADRAS/ Mechanical_Measurements (sub-module 2.4, Fig.29). Also refer https://www.google.co.in/search?q=thermistor+types&tbm=isch&tbo=u&source=univ&sa=X&ei=C8sqUpmNCcOPrQeqroDQDw&sqi=2&ved=0CFAQsAQ&biw=1280&bih=677

16. Discuss errors in temperature measurement due to surface radiation. Ans: Visit website nptel.iitm.ac.in/courses/IIT-MADRAS/ Mechanical_Measurements (sub-module 2.7)

17. Illustrate schematically, a black body furnace Ans: Visit website nptel.iitm.ac.in/courses/IIT-MADRAS/ Mechanical_Measurements (sub-module 2.5, figure 37)

18. Sketch and explain vanishing filament pyrometer. Ans: Visit website nptel.iitm.ac.in/courses/IIT-MADRAS/ Mechanical_Measurements (sub-module 2.5, figure 39)

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19. Mention the approximate surface emissivity values of the target materials, for temperature measurement using pyrometers.

Ans : Visit website nptel.iitm.ac.in/courses/IIT-MADRAS/ Mechanical_Measurements (sub-module 2.5, table 11)

20. Explain the working principle of a two colour pyrometer. Ans: Visit website nptel.iitm.ac.in/courses/IIT-MADRAS/ Mechanical_Measurements (sub-module 2.5, figure 43)

21. Explain the basics of transient temperature measurement

Ans: Visit website nptel.iitm.ac.in/courses/IIT-MADRAS/ Mechanical_Measurements (sub-module 2.6). Also refer: www.techbriefs.com/dl/ims122109.php?i=5003&d=1 and http://rsi.aip.org/resource/1/rsinak/v31/i3/p334_s1?isAuthorized=no

22. List the assumptions made in thermometer well problem

Ans: Please refer web resource nptel.iitm.ac.in/courses/IIT-MADRAS/Mechanical_Measurements (sub module 2.7)

Test your skills: 1. The temperature of boiling water at one standard atmospheric pressure is 100 deg C. What is its temperature in Kelvin?

Ans: 373.15K 2. If the temperatures of the two junctions of the thermocouple are same, what will be the voltmeter reading?

Ans: Zero

3. Identify the following:

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( a )

( b )

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