Temperature measuring devices types\

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2. GROUP MEMBERS
IHTESHAM UL HAQ
SYED SHEHBAZ AHMAD
FARMAN ULLAH
HAROON KHAN
NAVEED KHAN
AMIR HAMZA
Subject:- IPC
Instructor:- Engr ADNAN SUMROO
BUITEMS

3. Temperature
• Definition:- Temperature is the measure of the hotness or coldness of a
substance is known as temperature
• Coldness is caused because of absence of heat energy.
“motion of molecule due to KE”
• Hotness is caused because of presence of heat energy.
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5. Temperature measuring devices
1. Mechanical thermal sensors.
I. Bimetal strip thermometer.
II. Gas thermometer.
III. Vapour pressure thermometer.
IV. Liquid expansion thermometer.
2. Pyrometers
• Radiation pyrometer
• Infrared pyrometer
• Optical pyrometer etc
3. Thermojunctive.
• Thermocouples (heat energy into electrical energy)
4. Thermoresisitive.
• Thermistors
semiconductor resistance v/s temperature Inverssely proportional
• Resistance temperature detector (RTD)
Metal resistance v/s temperature Directly proportional
(Most commonly for relatively low
temperature)
(used for High temperatures).

6. Thermometer:--
• Definition:-Thermometer is a device that measures temperature or
a temperature gradient.Or
oA thermometer has two important elements:
ophysical change occurs with temperature.
ophysical change into a numerical value.
• Working principle:-The basis of the thermometer’s operation is the
thermal expansion of a working fluid(mercury in this case).
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7. Thermometer
Range :- 0 to 100 °C.
liquid-in-glass thermometers can
achieve a measurement uncertainty
of ±0.01 °C in the range 0 to 100 °C.
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1) Vapor pressure thermometers
• Definition :-
• The saturated vapor pressure of a volatile liquid is used as a
measure of the temperature.
• These thermometers are very sensitive but the scale is not linear.

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Working principle:-
• The liquid is partially stored in a closed vessels or container then the space above
the liquid will consist of evaporated vapors of the liquid at a pressure that depends
on the temperature.
• As the temperature increases the vapor pressure in the liquid increases and the
temperature of the material is measured.
Temperature range is from - 20° C to 280° C depending on the nature of the
gas.

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2) Liquid expansion ( thermometer) OR liquid pressure thermometer:-
• Definition:--
It’s a temperature measuring device whose operation is based on thermal expansion of a liquid.
• Working principle :-
• The insides of the thermo-sensor cylinder, capillary, and Bourdon tube are filled with Volatile liquid which
changes volume with varying temperature.
• The liquid in the thermo-sensor cylinder is expanded and contracted as the temperature changes, and the
pressure change in the Bourdon tube that is transmitted through the capillary is indicated as a temperature.
• Liquid filled thermometers have scales with divisions from 10° to 0.01°C.
• The measurement accuracy depends on the depth of immersion of the thermometer in the medium to be
measured.
• Range:- 80-400 ℃.

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Liquid pressure thermometer
1. A common application of this type of thermometer is measurement of outside temperature from the inside
of a building.

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Gas Thermometer:-
• Definition:- The type of sensors in which the gas is used in the tank which
is increase with the increase in the temperature.
• Working principle:-This sensors is based on basic law of gases, if gas is
kept in a container the pressure and volume is constant and the temperature
is changing. The ratio of gas pressure and temperature is a constant.
OR
• Pressure of a gas at constant volume with increase in temperature.
• The gas thermometer convert temperature information directly into pressure
signals. Useful in pneumatic systems.
• Mostly used inert gases Nitrogen gas is also used.

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Range:- -200 °C to 800 °C.

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4) Bimetallic Thermometer:
Definition:--A bimetallic strip is used to convert a temperature change into mechanical displacement.
The temperature is measured by means of a bimetal system inside the temperature sensor.
Working Principle:-
• The bimetal is made from two metal strips, permanently joined together, each metal
having a different thermal expansion coefficient.
• This causes the strip to deflect in proportion to the temperature variation.
• The actual bimetal system consists of a bimetal strip that is either helically or spirally
wound, depending on the size of the sensor and the temperature range to be measured.
• Any temperature variation causes the bimetal to rotate an attached spindle and it
is indicated by a pointer on a dial.

15. It is used for ON/OFF control in a system.
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• Range:- -70 to 600 °C OR -65 to 430 °C

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Bimetal Helix

17. Radiation Pyrometer:-
• Definition:- its is a type of thermometer which is used for measuring
temperature without any physical contact.
• Working principle:-When body is heated it emit a thermal energy
known as heat radiation. These radiation is passed into a better focus
and passes to a detector then the detector convert these signal into
electric signal and the AD converter convert the signal show measured
value on the display screen.
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18. RANGE:- 103 to 104 °K. For pyrometer -50 to 4000 °C RANGE DEPEND UPON FOR DIFFERENT APPLICATION
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20. Thermistor:-
• Definition:-An electrical resistor whose resistance is greatly reduced
by heating, used for measurement and control of temperature.
• Working principle:-It's resistance is depends upon temperature.
When temperature changes, the resistance of the thermistor changes in
a predictable way. Advantages,The benefits of using a thermistor is
accuracy and stability.
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Range:- −90 °C to 130 °C

22. Resistances temperature detector:-(RTD)
• Definition:- A Resistance Temperature Detector (RTD) is a device with
a significant temperature coefficient (that is, its resistance varies
with temperature)
• Working Principle:-Metal resistance increases with increase in
temperature.
• Valance electron in metal creates the increases in resistance with
temperature.
• Free electron in the valence shell.
• No gap between the valence and conduction band.
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24. Thermocouple:-
• Definition:-A Thermocouple is a sensor used to measure temperature.
• Working principle:-
• Thermocouples consist of two wire legs made from different metals.
• The wires legs are welded together at one end, creating a junction.
• This junction is where the temperature is measured.
• When the junction experiences a change in temperature, a voltage is
created also the change can be measured by an voltmeter.
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Range:-FOR j type= -150 to 745 °C
Range :- For s type= upto 1765 °C (other have above or below)

26. References:-
1. https://www.amazon.com/Process-Control-Instrumentation-Technology-8th/dp/0131194577
(by CURTON D JHONSON)
2.
https://books.google.com.pk/books/about/Principles_and_Methods_of_Temperature_Me.html?id=qfmS7g4JzjwC&redir_esc=y
( by Thomas D. McGee)
3. http://www.hayashidenko.co.jp/en/info04.html
4. http://www.wika.us/upload/BR_RF_Handbook_en_us_18447.pdf
WIKA-Handbook Pressure and Temperature Measurement U.S. Edition
5. https://www.youtube.com/results?search_query=nptel+lec+on+instrumentation+and+process+control
6. https://www.slideshare.net/anandprithviraj/mechanical-temperature-measuring-devices
( by Anand prith viraj)
7. https://www.slideshare.net/mohamedmusmar?utm_campaign=profiletracking&utm_medium=sssite&utm_source=ssslideview
(by Mohamed musmar )
8. https://docs.google.com/file/d/0Bz_j50pBnEarX3JUTDJ6ckFxU2c/view Chemical process controle by George Stephen apolus
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27. Q/A
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Quartz Crystal Thermometer for Measuring
Temperature Deviations in the 10−3 to 10−6 °C Range

28. Thank You
4/26/2018 Mechanical Temprature Mesurement 28