Brookfield DV2T - Page 41

Brookeld Engineering Labs., Inc. Page 41 Manual No. M13-167
value.Thezerovalueshouldnotshiftovertime,however,iftheuserdeterminesthat
thezeroisnotcorrect,youcanforceanAutoZerotobeperformedwithoutpowering
downtheviscometer.WhentheAutoZerofunctionisselected,theDV2Tisimmediately
settoAutoZeromodeandtheuserispresentedwiththeAutoZeroscreen(FigureII-2).
Uponcompletion,theuserwillbereturnedtotheDeviceSetupmenu.
Oscillation Check: TheOscillationCheckisacheckoftheperformanceofthelowerbearingof
theDV2TViscometer.ThislowerbearingiseitherPointandJewelorBall
Bearing.  Correct performance of the lower bearing is essential for proper
operationoftheviscometer.Afailedlowerbearingwillnormallycauseviscosity
measurementstobelowerthanexpected.
AnOscillationCheckisperformedasfollows:
• RemovethespindleandleveltheDV2TViscometer
• Gentlypushupontheviscometercoupling.
• Turnthecouplinguntilthe%Torquereadingis10–15%.
• Gentlyletgoofthecoupling.
• Watchthereading.The%Torquereadingshoulddecreasesmoothly
andoscillateabout0.0%.
SelectingOscillationCheckintheDeviceSetupmenuwillpresenttheuser
rstwithascreeninstructingtoleveltheviscometerandremovethespindle.
Conrmation of level and spindle removal will present the user with the
OscillationCheckscreenasshownbelow.
Figure IV-3
AsuccessfulOscillationCheckwillshowaverysmoothdecreaseof%Torque
withanalvaluewithin+/-0.2of0.0.Anyvalueabove0.2%orbelow-0.2%
indicatesthatacalibrationcheckshouldbeperformed(seeAppendixE).
TIP:HigherTorqueranges(HAandHB)willquicklyreturntothezero
valuewithoutdisplayingmuchoscillation.Thisisnormalbehavior.
TheOscillationCheckisnotaguaranteeofpropercalibration.Itisonlyan
indicationoftheperformanceofthelowerbearingoftheviscometer.Calibration
canonlybeveriedthroughtheuseofacalibrationstandardsuchasBrookeld
Silicone and Mineral Oil standards.