8/7/2019 Weigh Balance
1/12
Care and Maintenance
of the Weigh Balance
8/7/2019 Weigh Balance
2/12
Ohaus Voyager SeriesOhaus Voyager Series
Weigh BalanceWeigh Balance
8/7/2019 Weigh Balance
3/12
Importance of CalibratingImportance of CalibratingWeigh BalanceWeigh Balance
To ensure that the instrumentTo ensure that the instrumentaccurately weighs substances foraccurately weighs substances forreagent preparationreagent preparation
8/7/2019 Weigh Balance
4/12
Weigh Balance LocationWeigh Balance Location
Best environment for aBest environment for aweigh balance:weigh balance:
Free of vibrationFree of vibration
No large temperatureNo large temperature
fluctuationsfluctuations
No direct sunlight andNo direct sunlight and
No draftsNo drafts
8/7/2019 Weigh Balance
5/12
Weigh Balance CalibrationWeigh Balance Calibration
Calibration is important toCalibration is important toensure that the instrumentensure that the instrumentaccurately weighsaccurately weighssubstances for reagentsubstances for reagentpreparationpreparation
Test results may beTest results may be
incorrect due to instrumentincorrect due to instrumentmalfunctionmalfunction
8/7/2019 Weigh Balance
6/12
Use NIST Class S weights forUse NIST Class S weights forcalibrationcalibration
Verify that class S weights and balanceVerify that class S weights and balancepan are free from dust and fingerprintspan are free from dust and fingerprints
Only UserOnly User calibration will becalibration will be
discussed herediscussed here Note:Note:NEVERNEVERtouch the weights or thetouch the weights or the
balance pan with bare hands!balance pan with bare hands!
Weigh Balance CalibrationWeigh Balance Calibration(continued)(continued)
8/7/2019 Weigh Balance
7/12
The User method is used to calibrateThe User method is used to calibratethe balance using a mass of knownthe balance using a mass of knownvaluevalue
Three readings should be taken for theThree readings should be taken for thesix specified weights: 50, 100, 200,six specified weights: 50, 100, 200,500, 2000 and 4000500, 2000 and 4000
Record value in gramsRecord value in grams
User Calibration MethodUser Calibration Method
8/7/2019 Weigh Balance
8/12
Place selected mass value onPlace selected mass value on
balance panbalance pan
Record reading of weight of theRecord reading of weight of thecalibration masses. Removingcalibration masses. Removing
masses from pan returns balance tomasses from pan returns balance toweighing mode.weighing mode.
User Calibration MethodUser Calibration Method(continued)(continued)
8/7/2019 Weigh Balance
9/12
Balance Calibration WorksheetBalance Calibration Worksheet
Document eachDocument eachtime the balance istime the balance iscalibratedcalibrated
How often?How often?
Log should containLog should containat least theat least thefollowingfollowinginformation:information:
Balance Calibration Worksheet
Laboratory: ___________________
Balance: ______________________
alibration
heckDate: __________
Technician: ____________________
Precision/Repro
cibility: 0.1 mg
1 mg 10 mg 50 mg1. ______ 1. ______ 1. ______
2. ______ 2. ______ 2. ______
3. ______ 3. ______ 3. ______ Avg. ____ Avg. ____ Avg. ____
1 g 100 g1. ______ 1. ______ 2. ______ 2. ______
3. ______ 3. ______
Avg. ____ Avg. ____
ensitivity
erification:
Date Tech 10 mg 10 mg + 1 mg 50 mg 50 mg + 1 mg 100 g 100 g + 1 g
eviewed by: ____________________ Date: _____________
8/7/2019 Weigh Balance
10/12
Verify Sensitivity of the BalanceVerify Sensitivity of the Balance
To check sensitivity of the balance, keepTo check sensitivity of the balance, keepweighing paper on balance panweighing paper on balance pan
Make sure the balance reads zeroMake sure the balance reads zero Using tweezers, gently place the 10 mgUsing tweezers, gently place the 10 mg
weight on the balance weighing panweight on the balance weighing pan
fter the balance stops fluctuating, readfter the balance stops fluctuating, readthe weighing and record on the alancethe weighing and record on the alanceCalibration WorksheetCalibration Worksheet
8/7/2019 Weigh Balance
11/12
Verify Sensitivity of the BalanceVerify Sensitivity of the Balance
(continued)(continued)
While the 10 mg weight remains on theWhile the 10 mg weight remains on thebalance pan, using the tweezers, gentlybalance pan, using the tweezers, gently
add the 1 mg weightadd the 1 mg weight fter the balance stops fluctuating, recordfter the balance stops fluctuating, record
the reading in the alance Calibrationthe reading in the alance CalibrationWorksheetWorksheet
Repeat the above steps for each weighingRepeat the above steps for each weighingto complete the Sensitivity Verificationto complete the Sensitivity Verificationsection on the alance Calibrationsection on the alance Calibration
WorksheetWorksheet
8/7/2019 Weigh Balance
12/12
Maintenance and Care of BalanceMaintenance and Care of Balance
Keep balance cleanKeep balance clean -- daily, wipedaily, wipebalance with a damp clothbalance with a damp cloth
mild detergent may be usedmild detergent may be used
Never weigh materials directly onNever weigh materials directly onweigh panweigh pan
Keep calibration masses in a safe, dryKeep calibration masses in a safe, dry
placeplace Never touch the masses with bareNever touch the masses with bare
handshands
Cover balance when not in useCover balance when not in use
Top Related