pengukuran tempertur

Temperature Temperature MeasurementsMeasurementsMeasurementsMeasurements

In Jumanda KIn Jumanda [email protected]@gmail.com

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TemperaturTemperatur

�� Temperatur/suhu merupakan parameter fisik yang Temperatur/suhu merupakan parameter fisik yang banyak digunakan sebagai parameter kondisi operasi banyak digunakan sebagai parameter kondisi operasi pada suatu proses.pada suatu proses.

�� Suhu merupakan ukuran derajat aktivitas termal partikel Suhu merupakan ukuran derajat aktivitas termal partikel dalam material. dalam material. dalam material. dalam material.

�� Satuan temperatur dalam SI: Satuan temperatur dalam SI: ooC dan KC dan K

�� Satuan temperatur dalam British: Satuan temperatur dalam British: ooF dan RF dan R

Temperature MeasurementsTemperature Measurements 22Measurement Fundamental Measurement Fundamental -- IJK & IJK &

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TermometerTermometer�� PengukuranPengukuran suhusuhu menggunakanmenggunakan termometertermometer

memanfaatkanmemanfaatkan pemuaianpemuaian//penyusutanpenyusutan cairancairanakibatakibat kenaikankenaikan//penurunanpenurunan suhusuhu

�� PembacaanPembacaan suhusuhu dilakukandilakukan melaluimelalui pembacaanpembacaantinggitinggi permukaanpermukaan cairancairan padapada pipapipa kapilerkapiler..

�� CairanCairan dalamdalam temperaturtemperatur dandan rentangrentangpengukurannyapengukurannya::pengukurannyapengukurannya::


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Respon Dinamik ThermometerRespon Dinamik Thermometer


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ThermocouplesThermocouples

�� Prinsip Kerja ThermocouplesPrinsip Kerja Thermocouples

–– Seebeck in 1821 discovered that Seebeck in 1821 discovered that thermal thermal electromotive force (t.e.m.f.) is generated in a closed electromotive force (t.e.m.f.) is generated in a closed circuit of two wires made of dissimilar metals if two circuit of two wires made of dissimilar metals if two junction are at different temperaturesjunction are at different temperatures. . junction are at different temperaturesjunction are at different temperatures. .

–– One junction is inserted into a measuring media, and One junction is inserted into a measuring media, and it is called ait is called a hothot or or measuring junctionmeasuring junction. .

–– Another one, called a Another one, called a coldcold or or reference junctionreference junction, is , is kept either at 0 kept either at 0 °°C or at ambient temperature and is C or at ambient temperature and is connected to a measuring instrument (millivoltmeter). connected to a measuring instrument (millivoltmeter).


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11 -- hot junction;hot junction;

22 -- metal A;metal A;

33 -- metal B;metal B;

44 -- connection head;connection head;

55 -- extension wires;extension wires;

6, 76, 7 -- positive and negative terminals, respectively, of a measuring positive and negative terminals, respectively, of a measuring instrument;instrument;

88 -- measuring instrument.measuring instrument.


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Temperature MeasurementsTemperature MeasurementsMeasurement Fundamental Measurement Fundamental -- IJK & IJK &

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Thermocouples AssemblyThermocouples Assembly


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TermokopelTermokopel�� TipeTipe TermokopelTermokopel

TabelTabel TipeTipe termokopeltermokopel MenurutMenurut Standard Instrument Society Of Standard Instrument Society Of America America (ISA)(ISA)

TipeTipe BahanBahan RentangRentang SuhuSuhu(C)(C)

GGL (V)GGL (V)

BB Platina, 6% Rodium (+) Platina, 6% Rodium (+) dan Platina, 30% Rodium (dan Platina, 30% Rodium (--))

0… 18200… 1820 0… 13,8140… 13,814

RR Platina (+) Platina (+) dan platina, 13% Rodium (dan platina, 13% Rodium (--))

--50… 176850… 1768 --0,226… 21,1080,226… 21,108

SS Platina (+) Platina (+) dan platina, 10% Rodium (dan platina, 10% Rodium (--))

--50… 176850… 1768 --0,236… 18,6980,236… 18,698

JJ Besi (+) dan Konstantan (Besi (+) dan Konstantan (--)) --210… 760210… 760 --8,096… 42,9228,096… 42,922

KK Khromel (+) dan Alumel (Khromel (+) dan Alumel (--)) --270… 1372270… 1372 --6,458… 54,8756,458… 54,875

TT Tembaga (+) dan Konstantan (Tembaga (+) dan Konstantan (--)) --270… 400270… 400 --6,258… 20,8696,258… 20,869

EE Khromel (+) dan Konstantan (Khromel (+) dan Konstantan (--)) --270… 1000270… 1000 --9,835… 76,3589,835… 76,358


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Experimental curves Experimental curves

thermal electromotive forcethermal electromotive force vs vs temperaturetemperature..

30

40

50

60

Th

erm

al e

lect

rom

oti

ve f

orc

e, m

V

Type K

Type J

-10

0

10

20

30

-300 0 300 600 900 1200 1500 1800

Temperature, C

Th

erm

al e

lect

rom

oti

ve f

orc

e, m

V

Type J

Type T

Type S


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Pembangkitan TeganganPembangkitan Tegangan

PersamaanPersamaan TermokopelTermokopel

( ) ( )22 TTβTTαE −+−= ( ) ( )22

2121 TTβTTαE −+−=

Process Variable Process Variable MeasurementMeasurement 1111Measurement Fundamental Measurement Fundamental -- IJK&teamIJK&team


LATIHANLATIHAN--11

TermokopelTermokopel menghasilkanmenghasilkan GGLGGL sebesarsebesar1212 mVmV padapada suhusuhu titiktitik dingindingin 2020ooCC.. JikaJika ααadalahadalah 33,,55 xx 1010--22 dandan ββ adalahadalah 88,,22 xx 1010--66,,adalahadalah 33,,55 xx 1010--22 dandan ββ adalahadalah 88,,22 xx 1010--66,,hitunghitung berapaberapa suhusuhu titiktitik panaspanas..



LATIHANLATIHAN--22

DiketahuiDiketahui konstantakonstanta materialmaterial termokopeltermokopelαα == 33,,55 xx 1010--22 dandan ββ == 88,,22 xx 1010--66..TentukanTentukan tegangantegangan termokopeltermokopel (mV)(mV) jikajikaTentukanTentukan tegangantegangan termokopeltermokopel (mV)(mV) jikajikatitiktitik panaspanas 220220 ooCC dandan titiktitik dingindingin 2020 ooCC..


Resistance Temperature Resistance Temperature DetectorsDetectors (RTD)(RTD)

�� The principle of resistance temperature The principle of resistance temperature detectors (RTD) is based on the variation of detectors (RTD) is based on the variation of electrical resistance of metals with temperature. electrical resistance of metals with temperature.

�� For this purpose several metals are used, For this purpose several metals are used, namely, platinum, copper, nickel. namely, platinum, copper, nickel. namely, platinum, copper, nickel. namely, platinum, copper, nickel.

�� When temperature increases the resistance of When temperature increases the resistance of these metals increases. these metals increases.

�� Temperature function of resistance for metals in Temperature function of resistance for metals in a narrow temperature interval can be expressed a narrow temperature interval can be expressed by a relationship:by a relationship:


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Resistance Temperature Resistance Temperature DetectorsDetectors (RTD)(RTD)

�� The principle of resistance The principle of resistance temperature detectors (RTD) is temperature detectors (RTD) is based on the variation of based on the variation of electrical resistance of metals electrical resistance of metals with temperature. with temperature.

�� When temperature increases the When temperature increases the resistance of these metals resistance of these metals increases. increases.

�� For this purpose several metals For this purpose several metals are used, namely, platinum, are used, namely, platinum, copper, nickel. copper, nickel.


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R T DR T D

�� Temperature function of resistance for metals in a Temperature function of resistance for metals in a narrow temperature interval can be expressed by a narrow temperature interval can be expressed by a relationship:relationship:

RRϑϑ = R= R00 (1 + (1 + αϑαϑ))RRϑϑ = R= R00 (1 + (1 + αϑαϑ))

�� RRϑϑ and and RR00 -- are the values of electrical resistance of a are the values of electrical resistance of a metal conductor at temperatures metal conductor at temperatures

�� αα -- thermal coefficient of electrical resistance, thermal coefficient of electrical resistance,


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Resistance vs temperature for Resistance vs temperature for Platinum and Copper RTD.Platinum and Copper RTD.

250

300

350

400R

, Oh

m

Platinum RTD

Copper RTD

0

50

100

150

200

-300 -100 100 300 500 700 900

t, oC

R, O

hm


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Platinum and Copper RTDPlatinum and Copper RTD

�� Platinum RTDs are used for temperature Platinum RTDs are used for temperature measurements from measurements from --220 to 850 oC 220 to 850 oC

�� copper RTD copper RTD -- from from --50 to 150 oC, and 50 to 150 oC, and Nickel RTD Nickel RTD -- from from --215 to 320 oC.215 to 320 oC.Nickel RTD Nickel RTD -- from from --215 to 320 oC.215 to 320 oC.


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Pengaruh Suhu pada Resistansi Pengaruh Suhu pada Resistansi

�� DETEKTOR SUHU RESISTANSI DETEKTOR SUHU RESISTANSI ((Resistance Temperature DetectorResistance Temperature Detector, RTD) , RTD)

( )TRR α+= 1( )TRR o α+= 1

( )21 TTRR o βα −+=





LATIHANLATIHAN

Sensor PTSensor PT--100 memiliki hubungan antara suhu 100 memiliki hubungan antara suhu dan resistansi sebagai berikut.dan resistansi sebagai berikut.

R = 100 + 0,385 TR = 100 + 0,385 T

Jika R pada suhu T 111,3 ohm, berapa suhu T?Jika R pada suhu T 111,3 ohm, berapa suhu T?


Sistem Termal IsianSistem Termal Isian(Filled Thermal System)(Filled Thermal System)

�� Sistem termal isian bekerja berdasarkan prinsip Sistem termal isian bekerja berdasarkan prinsip pemuaian fluida.pemuaian fluida.

�� Piranti ini dibedakan menjadi dua jenis, yaitu berdasar Piranti ini dibedakan menjadi dua jenis, yaitu berdasar perubahan volume dan tekanan.perubahan volume dan tekanan.perubahan volume dan tekanan.perubahan volume dan tekanan.

�� Pada jenis pertama, sensor berisi cairan. Pada jenis Pada jenis pertama, sensor berisi cairan. Pada jenis kedua, sensor berisi gas atau campuran uap dan cair.kedua, sensor berisi gas atau campuran uap dan cair.

�� SAMA (Scientific Apparatus Makers Association) SAMA (Scientific Apparatus Makers Association) memberikan klasifikasi sistem termal isian.memberikan klasifikasi sistem termal isian.


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Tabel Klasifikasi SAMA untuk sistem isianTabel Klasifikasi SAMA untuk sistem isian

KlasifikasiKlasifikasi UraianUraian

IILiquid Liquid ––filled volume filled volume ––change (selain merkuri)change (selain merkuri)IA IA –– Full compensationFull compensationIB IB –– Case compensationCase compensation

VaporVapor--filled pressurefilled pressure--changechange

IIII

VaporVapor--filled pressurefilled pressure--changechangeIIA IIA –– Dirancang untuk suhu di atas suhu lingkunganDirancang untuk suhu di atas suhu lingkunganIIB IIB –– dirancang untuk suhu dibawah suhu lingkungandirancang untuk suhu dibawah suhu lingkunganIIC IIC –– Dirancang untuk suhu diatas dan bawah suhu lingkunganDirancang untuk suhu diatas dan bawah suhu lingkunganIID IID –– Dirancang untuk seluruh suhuDirancang untuk seluruh suhu

IIIIIIGasGas--Filled pressureFilled pressure--changechangeIIIA IIIA –– full compensationfull compensationIIIB IIIB –– case compensationcase compensation

IVIVMercuryMercury--filled volume changefilled volume changeVA VA –– full compensationfull compensationVB VB –– case compensationcase compensation


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�� Sistem Isian CairSistem Isian Cair



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�� Sistem Isian UapSistem Isian Uap

Kelas IIAKelas IIA Kelas IIBKelas IIB


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�� Sistem Isian GasSistem Isian Gas

Kelas IICKelas IIC Kelas IIDKelas IID


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Filled Thermal SystemFilled Thermal System

�� KeunggulanKeunggulan�� small dimensions of thermal bulb.small dimensions of thermal bulb.

�� KelemahanKelemahan�� KelemahanKelemahan�� narrow temperature range, from narrow temperature range, from --50 to 300 50 to 300 °°C;C;

�� slow response time (time lag) of about 20 slow response time (time lag) of about 20 seconds;seconds;

�� nonnon--uniformity of the temperature scale.uniformity of the temperature scale.


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Saturation (vapour pressure) curve Saturation (vapour pressure) curve for methyl chloride.for methyl chloride.

2.0

2.5

3.0

3.5

Vap

ou

r (s

atu

rati

on

) p

ress

ure

, MP

a

Methyl chloride

0.0

0.5

1.0

1.5

2.0

0 20 40 60 80 100Temperature, C

Vap

ou

r (s

atu

rati

on

) p

ress

ure

, MP

a


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Termometer BimetalTermometer Bimetal(Bimetallic Strip Thermometer)(Bimetallic Strip Thermometer)

�� Bekerja dengan prinsip bahwa logam akan memuai Bekerja dengan prinsip bahwa logam akan memuai jika dikenai panas dan koefisien pemuaiannya untuk jika dikenai panas dan koefisien pemuaiannya untuk setiap jenis logam akan berbeda.setiap jenis logam akan berbeda.

�� Elemen yang sensitif terhadap suhu adalah campuran Elemen yang sensitif terhadap suhu adalah campuran antara dua jenis logam yang dikeraskan menjadi antara dua jenis logam yang dikeraskan menjadi antara dua jenis logam yang dikeraskan menjadi antara dua jenis logam yang dikeraskan menjadi lempengan berbentuk pita.lempengan berbentuk pita.


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ThermistorsThermistors( ‘thermally sensitive resistor’). ( ‘thermally sensitive resistor’).

�� If semiconductors or heatIf semiconductors or heat--treated metallic oxides treated metallic oxides (oxides of cobalt, copper, iron, tin, titanium, (oxides of cobalt, copper, iron, tin, titanium, etc.) are used as the materials for producing etc.) are used as the materials for producing temperature sensitive elements. temperature sensitive elements.

�� These oxides are compressed into the desired These oxides are compressed into the desired �� These oxides are compressed into the desired These oxides are compressed into the desired shape from the specially formulated powder. shape from the specially formulated powder.

�� After that, the oxides are heatAfter that, the oxides are heat--treated to treated to recrystallise them. recrystallise them.

�� As the result of this treatment the ceramic body As the result of this treatment the ceramic body becomes dense.becomes dense.


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TERMISTORTERMISTOR

�� Termistor terbuat dari bahan semikonduktorTermistor terbuat dari bahan semikonduktor

�� Koefisien negatif: Koefisien negatif: NTCNTC

Koefisien positif:Koefisien positif: PTCPTC�� Koefisien positif:Koefisien positif: PTCPTC

�� Hubungan antara R dan T,Hubungan antara R dan T,

R = A eR = A eB/TB/T





�� KeunggulanKeunggulan TermistorTermistor

–– UkuranUkuran sensorsensor cukupcukup kecilkecil..

–– TidakTidak adaada problemproblem resistansiresistansi kawatkawat penghubungpenghubung((sebabsebab resistansiresistansi termistortermistor cukupcukup tinggitinggi))..((sebabsebab resistansiresistansi termistortermistor cukupcukup tinggitinggi))..

–– PerubahanPerubahan resistansiresistansi sangatsangat besarbesar ((kirakira--kirakira 1010 kalikaliRTD)RTD)..

–– TahanTahan goncangangoncangan..



KelemahanKelemahan TermistorTermistor

�� HubunganHubungan resistansiresistansi termistortermistor terhadapterhadap suhusuhu sangatsangattidaktidak linierlinier

�� HanyaHanya dapatdapat digunakandigunakan untukuntuk rentangrentang suhusuhu yangyang�� HanyaHanya dapatdapat digunakandigunakan untukuntuk rentangrentang suhusuhu yangyangsempitsempit ((dibatasidibatasi suhusuhu maksimummaksimum semikonduktorsemikonduktor yangyangratarata--ratarata sampaisampai 150150 ooCC))..


PirometerPirometer

�� PirometerPirometer digunakandigunakan untukuntuk mengukurmengukur suhusuhu berdasarberdasarprinsipprinsip radiasiradiasi termaltermal yangyang dipancarkandipancarkan bendabenda..

�� KelebihanKelebihan pirometerpirometer adalahadalah,, tidaktidak menyentuhmenyentuh objekobjekterukurterukur..

�� DenganDengan demikiandemikian pengukuranpengukuran hampirhampir tidaktidak�� DenganDengan demikiandemikian pengukuranpengukuran hampirhampir tidaktidakmempengaruhimempengaruhi suhusuhu bendabenda..

�� PirometerPirometer banyakbanyak digunakandigunakan untukuntuk mengukurmengukur lelehanlelehanbesibesi dandan suhusuhu tanurtanur pembakaranpembakaran..


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Perbandingan Beberapa Metode

Sensor Type Limits of Application (°C)

Accuracy1,2 Dynamics:t (s)

Advantages Disadvantages

Thermocoupletype E:

chromel-constantan-100 to 1000

±1.5 or 0.5% for 0 to 900 °C

see note 3

-good reproducibility

-wide range -minimum span of 40 °C

-temperature vs. emf

not exactly linear

-drift over time

-low emf corrupted by

noise

type J:

iron-constantan0 to 750 ±2.2 or 0.75%

type K:chromel-nickel

0 to 1250 ±2.2 or 0.75%

type T:copper-constantan

-160 to 400±1.0 or 1.5% for

-160 to 0 °Ccopper-constantan -160 to 0 °C

RTD -200 to 650 0.15 + 0.2|T| see note 3-good accuracy

-small span possible

-linearity

-self-heating

-less physically rugged

-self-heating error

Thermister -40 to 150 ± 0.10 °C see note 3-good accuracy

-little drift

-highly nonlinear

-only small span

-less physically rugged

-drift

Bimetallic - ± 2% --low cost

-physically rugged-local display

Filled system -200 to 800 ± 1% 1 to 10-simple and low cost

-no hazards

-not high temperatures

-sensitive to external

pressure


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pengukuran tempertur