cover the temperature measurement tools

2. TEMPERATURE MEASUREMENT
AND ITS SCALE

3. GROUP MEMBERS
• Nauman Aslam 13-ME-47
• Raja Sami 13-ME-49
• Rameez Raja 13-ME-51
• Saeed Anwar 13-ME-53
• Shshbaz Haider 13-ME-55

4. TEMPERATURE
• Definition
 Correlates to molecular kinetic energy

5. TEMPERATURE
 Units
 Centigrade (C)
 Fahrenheit (F)
 Kelvin (K)
• Symbol
 T

6. TEMPERATURE MEASURING
SCALES
• Centigrade
 Denoted by °C
 Water freezes at O°C and boils at 100°C
• Fahrenheit
 Denoted by °F
 Water freezes at 32°F and boils at 212°F
• Kelvin
 Denoted by K
 Water freezes at 273K and boils at 373K

7. INTER CONVERSION
• C to F
• F=9/5C+32
• F to C
• C=5/9(F-32)
• C to K
• K=c+273

8. TEMPERATURE MEASUREMENT
• Expansion thermometers
• Thermocouples
• RTDs (Resistive Temperature Devices)
• Thermistors
• Integrated Circuits
• Optical pyrometers
• Infrared thermometers

9. EXPANSION THERMOMETER
• Expansion thermometers
• Common
• Inexpensive
• Huge thermal mass
• Very slow to respond

10. EXPANSION THERMOMETER
• Mercury glass thermometer
• Thermal expansion
• Commonly used in clinics

11. EXPANSION THERMOMETER
• Alcohol thermometer
• Thermal expansion
• Commonly used in Labs

12. BI METALLIC STRIP THERMOMETER
• Bimetallic strip thermometers
• Dial
• Convenient
• Inexpensive
• Poor accuracy and precision

13. THERMOCOUPLES
• Two different metals are joined together
• Change in temperature cause magnetic field
• Seekbeck effect
• Voltage can be interpreted in readable temperature

14. THERMOCOUPLES
• Seebeck Effect
• Any conductor subjected to a temperature gradient generates a potential difference
• Working principle of thermocouples

15. THERMOCOUPLES
• Type K
• the most common general purpose thermocouple
• −200 °C to +1350 °C
• constituent metals is Nickel
• Cause magnetic field @ curie temperature
• @ 354 °C.

16. THERMOCOUPLES
• Type E
• It is non-magnetic.
• Cryogenic use
• 68 µV/°C
• Type J
• Less popular then K type
• −40 to +750 °C
• 50 µV/°C
• The Curie point of the iron 770 °C

17. COMPARISON

18. RTD
• Electronic technology
• resistance temperature detectors
• correlating the resistance
• element is usually quite fragile
• Pure material, typically platinum, nickel or copper
• slowly replacing the use of thermocouples (<600 C)

19. RTDS TYPE
• wire wounded
• Coil and type

20. RTDS TYPE
• Thin film type

21. THERMISTORS
• Resistance is dependent on temperature
• ceramic or polymer
• −90 °C to 130 °C

22. THERMISTOR TYPES
• Positive temperature coefficient (PTC)
• Negative temperature coefficient (NTC)
• Silistor

23. COMPARISON

24. IC TEMPERATURE SENSORS
• Two terminal integrated circuit
• Produce an output current
• Sensor package is small
• low thermal mass and a fast response
• 55 to 150°C

25. COMPARISON

26. OPTICAL PYROMETER
• Body of interest must emit in the visible
• Ancient technology
• Temperature measured at least 650 C

27. INFRARED THERMOMETERS
• Thermal detectors
• Bolometers, pyroelectric detectors
• Radiation causes temperature of detector to rise