€¦ · Datasheet Documents Hookup Diagrams 3 `Celsius `Fahrenheit Kelvin °F =1.8 ×°C+32 ` `...
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By: Mr Razavipanah By: Mr.Razavipanah 1
Transcript of €¦ · Datasheet Documents Hookup Diagrams 3 `Celsius `Fahrenheit Kelvin °F =1.8 ×°C+32 ` `...
By: Mr RazavipanahBy: Mr.Razavipanah
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General ConceptsGeneral ConceptsPressure Measurement Temperature MeasurementTemperature Measurement Level Measurement lFlow Measurement
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Temperature Measurementp◦ Temperature Units◦ Contact Methods
ThermocouplepRTDThermistorBi-metalFilled DevicesStem Glass
N M h d◦ Non-contact MethodsInfra red method
Th ll◦ Thermowell◦ Datasheet Documents◦ Hookup Diagrams
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CelsiusCelsiusFahrenheitKelvin
328.1 +°×=° CFKelvinRankin
273+°=° CK460+°=° FRKR °×=° 8.1
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Law of Intermediate Law of IntermediateLaw of IntermediateMetals
Law of Intermediate Temperatures
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Tamb=25ºCV=6.5mVTprocess=?
T =25ºC V =1mVTamb=25 C Vamb=1mV6.5mV + 1mV = 7.5mV Tprocess=184ºC
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PlatinumPlatinum◦ PT100◦ PT500PT500◦ PT1000CopperCopperNickel
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2 wire2 wire3 wire
4 wire
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A thermistor is a semiconductor deviceA thermistor is a semiconductor device formed from metal oxides. The principle of temperature measurement with a thermistortemperature measurement with a thermistoris that its resistance changes with temperature.temperature.
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Thermistor types:Thermistor types:◦ NTC (Negative temperature coefficient)◦ PTC (Positive temperature coefficient)PTC (Positive temperature coefficient)
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Advantages:S ll i F t V hi h iti it◦ Small size, Fast response, Very high sensitivity, Polarity insensitive
Disadvantages:Disadvantages:◦ Unstable, Non linear, Narrow span, Fragile, High
resistance, noise problemsresistance, noise problems
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Class I: LiquidC ass qu dClass II: VaporClass III: GasClass III: GasClass IV: Mercury
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Low cost Simplicity No recalibration requiredLow cost, Simplicity, No recalibration requiredLocalised measurement only, Isolated from other control and recording equipmentother control and recording equipment, Fragile
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A+R+T=1NKTTV ε=)( )(
TN λ/14388=
Emissivity:ε
19eTemperaturT
Emissivity::ε
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Removal or replacement of the sensing deviceRemoval or replacement of the sensing device without opening up the process tank or pipingpipingProtection of sensing elementIncreasing response timeIncreasing response time
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Thermowell ThermowellThermowellconnection types:
Thermowellconstruction types:
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h kh kThank youThank youyy
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