Brookfield DV2T Viscometer Instrukcja Użytkownika Pobierz pdf (Strona 65)

Brookeld Engineering Labs., Inc. Page 65 Manual No. M13-167-B0614

1) Viscositymeasurementsshouldbeacceptedwithintheequivalent%TorqueRange

from10%to100%foranycombinationofspindle/speedrotation.

2) Viscositymeasurementsshouldbetakenunderlaminarowconditions,notunder

turbulentowconditions.

Therstconsiderationhastodowiththeprecisionoftheinstrument.AllDV2TViscometers

haveanaccuracyof+/-1%oftherangeinuseforanystandardspindleorcone/platespindle.

(Notethataccuracyvaluesmaybehigherthan1%whenusingaccessorydeviceswiththe

DV2T).Wediscouragetakingreadingsbelow10%ofrangebecausethepotentialviscosity

errorof+/-1%isarelativelyhighnumbercomparedtotheinstrumentreading.

Thesecondconsiderationinvolvesthemechanicsofuidow.Allrheologicalmeasurements

ofuidowpropertiesshouldbemadeunderlaminarowconditions.Laminarowisow

whereinallparticlemovementis in layers directedbytheshearingforce.Forrotational

systems,thismeansalluidmovementmustbecircumferential.Whentheinertialforces

ontheuidbecometoogreat,theuidcanbreakintoturbulentowwhereinthemovement

ofuidparticlesbecomesrandomandtheowcannotbeanalyzedwithstandardmath

models.Thisturbulencecreatesafalselyhighviscometerreadingwiththedegreeofnon-

linearincreaseinreadingbeingdirectlyrelatedtothedegreeofturbulenceintheuid.

Forthefollowinggeometries,wehavefoundthatanapproximatetransitionpointtoturbulent

owoccurs:

1) No.1LVSpindle:  15cPat60RPM

2) No.2LVSpindle:  100cPat200RPM

3) No.1RVSpindle:  100cPat50RPM

4) ULAdapter:   0.85cPat60RPM

TurbulentconditionswillexistinthesesituationswhenevertheRPM/cPratioexceedsthe

values listed above.

Eect on accuracy when using accessory devices

TheBrookeldviscometerhasastatedaccuracyof+/-1%oftherangeinuse.Thisstated

accuracyapplieswhentheviscometerisusedinaccordancewiththeoperatinginstructions

detailedintheinstrumentinstructionmanualandthecalibrationtestuidisusedinaccordance

with the instructions provided by the uid supplier (including the critical parameters of

temperaturecontrolandstateduidaccuracy).Brookeld’saccuracystatementof+/-1%of

therangeinuseappliestotheBrookeldrotationalviscometerwhenusedwiththestandard

spindlessuppliedwiththeinstrument,includingLVspindles1through4(suppliedwithLV

seriesviscometers),RVspindles2through7(suppliedwithRVseriesviscometers),andHV

seriesspindles2through7(suppliedwithHAseriesviscometersandHBseriesviscometers)

ina600mLlowformGrifnbeaker.

BrookeldoffersarangeofaccessoriesforusewiththeBrookeldviscometertoaccommodate

specialmeasurementcircumstances.Theseaccessories,whileofferingaddedcapability

totheuser,alsocontributetoanexpandedmeasurementtolerancebeyondtheinstrument

accuracyof+/-1%oftherangeinuse.Thisexpandedmeasurementtoleranceisafunction

of many parameters including spindle geometry, accessory alignment accuracy, sample

volumerequirement,andsampleintroductiontechniques.Theeffectoftheseelementson

measurementtolerancemustbeconsideredwhenverifyingthecalibrationofyourBrookeld

viscometer.Sampletemperatureinalltestcircumstancesisveryimportant,andwillalso

addanadditionalexpandedtolerancedependingonthetemperaturecontrolsystemandthe

calibrationvericationtestsbeginwiththestandardviscometerspindlesasdetailedabove.

Oncethecalibrationoftheviscometeritselfis conrmed, the expandedtoleranceofthe

measurementsystemmaybedeterminedusingaccessorydevices.Inmanycases,this

additionaltolerancewillbeveryminimal,butasageneralstatement,theadditionof+/-1%

oftherangeinuseisreasonableforaccessories.

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Sachin Vaijanath Ashture 05 Mar 2025 | 15:48:33

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Brookfield DV2T Viscometer Instrukcja Użytkownika Strona 65

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