1569‐PT060EE1 Rev.7 Page40of62
5.5 Calibration
5.5.1 Theoretical calibration procedure
Ingeneral,thebestcalibrationmethodconsistsinapplyingaknownweight(sampleweight)ontheweighingsystem.
Thismethodisnotalwayspossibletoexecute,whenweightsboastingatoohighmassareused.Othersystems
implemented,incaseoflargesizetanks,consistof:useoftestedlitre
countersorfillingwithaspecificwaterquantity.
Incaseoftanksoflargecapacity,whensufficientcalibrationweightsarenotavailableorgeometriesdonotallow
loadinglargemasses,calibrationiscarriedwithsubstituteweights:
1. Thetankisloadedwithknownweightmasses
2. Thevaluereadby
theindicatorisrecorded
3. Theknownweightsareremoved
4. Thetankisloadedwiththematerial(orwater,ormaterialusedbythesystem)untilreachingtheweight
valueindicatedinpoint1
5. Re‐loadthesameweightspreviouslyloadedinpoint1
6. Thevaluereadbytheindicatorisrecorded
7. Theknownweightsareremovedonceagain
8. Thetankisloadedwiththematerialuntilreachingtheweightvalueindicatedinpoint3
9. Repeatsteps1and2untilreachingthenominalload,thencorrectthecalibrationcurve(SPAN)ifneeded.
Duringthe
calibrationphase,byusingknownmasses,itispossibletochecktheinterferencesanderrorscausedbythe
applicationoftheloadonmechanicalpartsorloadcells.
AftercarryingouttheconfigurationstepsoftheTHEORETICALcalibration(settingofthenominalcapacityoftheload
cellssystemandrelativesensitivity),
itisagoodpracticetocheckthesystem’scalibration.
Calibrationconsistsofthefollowingsteps:
Tarewithpermanentstorage
Calibrationofthezerovalue
Calibrationoffullscale
Linearization
Zeroandfullscalecalibrationsdefinetheinstrument’scalibrationcurve.
OFFS 1
Permanenttare.Thisfunctionallowscalibratingandstoringthereset
valueinanon‐volatilememory,differentlyfromthevaluereset
throughinput,whichislostwhentheequipmentisturnedoff.
Resettingdoesnotaltertheslopeofthecalibrationcurve.
2ERO 1
Zerocalibration
SPAN 1
Fullscalecalibration
LIN 1-2-3-4-5-6-7-8-9
Linearization