Brookfield DV3T - Page 110

Brookeld Engineering Labs., Inc. Page 110 Manual No. M13-167-A0415
BrookeldViscosityStandardsFluidsareaccurateto(+/-)1%oftheirstatedvalue.
Example:
 CalculatetheacceptablerangeofviscosityusingDV3TRVwithRV-3Spindleat
2RPM;BrookeldStandardFluid12,500withaviscosityof12,257cPat25°C:
1) Calculatefullscaleviscosityrangeusingtheequation:
Full Scale Viscosity Range [cP] = TK
*
SMC
*
10,000
RPM
Where:
TK-1.0fromTable D-2
SMC=10fromTable D-1
Full Scale Viscosity Range
1
*
10
*
10,000
=
50,000 cP
2
 Theviscosityisaccurateto(+/-)500cP(whichis1%of50,000)
2) Theviscositystandarduidis12,257cP.Itsaccuracyis(+/-)1%of12,257or
 (+/-)122.57cP.
3) Totalallowableerroris(122.57+500)cP=(+/-)622.57cP.
4) Therefore,anyviscosityreadingbetween11,634.4and12,879.6cPindicatesthattheRheometer
isoperatingcorrectly.AnyreadingoutsidetheselimitsmayindicateaRheometerproblem.
ContacttheBrookeldtechnicalsalesdepartmentoryourlocalBrookelddealer/distributor
withtestresultstodeterminethenatureoftheproblem.
Example:
Calculate the acceptable accuracy for viscosity measurement using DV3TLV
withSC4-21spindleinSmallSampleAdapterat6,12,and30RPM.Brookeld
viscositystandarduid100cPshasanactualvalueof101.5cPat25ºC.
1) Calculatethefull scale viscosity rangeeitherby using theSpindleRange Coefcient in
AppendixBofMoreSolutionstoStickyProblemsorbyusingtheAutoRangebuttononyour
rheometer.
 TheSpindleRangeCoefcientforthe21spindleonanLVTorqueinstrumentis4,688.
 At6RPM,theFullScaleRange(FSR)viscosityis781cP.Allow+/-1%fortherheometer
and+/-1%fortheSmallSampleAdapter.Totalallowableaccuracyis:
  +/-2%x781cP=+/-15.6cP
 Asimilarcalculationat12RPMgivesFSR=391cP:+/-2%x391cP=+/-7.8cP
 Asimilarcalculationat30RPMgivesFSR=156cP:+/-2%x156cP=+/-3.1cP
2) TheViscosityStandardFluidis101.5cP.Itsaccuracyis:
  +/-1%x101.5cP=+/-1.015cPorroughly+/-1.0cPforfurthercalculations.
3) Totalaccuracyisthesumofthevaluesn(1)and(2):
  At6RPM,accuracyis:15.6cP+1.0cP=+/-16.6cP
  At12RPM,accuracyis:7.8cP+1.0cP=+/-9.8cP
  At30RPM,accuracyis:3.1cP=1.0cP=+/-4.1cP