Hanna Instruments HI 95734 User manual

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Instruction Manual
HI 95734
Free & Total Chlorine
High Range ISM
www.hannacan.com ThisInstrumentisin
CompliancewiththeCEDirectives

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Allrightsarereserved.Reproductioninwholeorinpartisprohibitedwithoutthewrittenconsent
ofthecopyrightowner,HannaInstrumentsInc.
TABLE OF CONTENTS
PRELIMINARYEXAMINATION...........................................................................................3
GENERALDESCRIPTION..................................................................................................4
ABBREVIATIONS ...........................................................................................................4
SPECIFICATIONS ...........................................................................................................5
PRECISIONANDACCURACY ............................................................................................5
PRINCIPLEOFOPERATION..............................................................................................6
FUNCTIONALDESCRIPTION.............................................................................................7
GUIDETODISPLAYCODES .............................................................................................9
GENERALTIPSFORANACCURATEMEASUREMENT ..........................................................11
OPERATIONALGUIDE...................................................................................................14
MEASUREMENTPROCEDURE ........................................................................................15
VALIDATIONPROCEDURE .............................................................................................17
CALIBRATIONPROCEDURE............................................................................................18
BATTERYREPLACEMENT ...............................................................................................20
ACCESSORIES ............................................................................................................21
CEDECLARATIONOFCONFORMITY ................................................................................21
WARRANTY ............................................................................................................22
HANNALITERATURE ....................................................................................................22
USERNOTES ............................................................................................................23
DearCustomer,
Thank you for choosing a Hanna product. This manual will provide you with the
necessary information for the correct use of the instrument. Please read it carefully
before using the meter. If you need additional technical information, do not hesitate to
e-mail us at [email protected].
This instrument is in compliance with directives.

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PRELIMINARY EXAMINATION
Pleaseexaminethisproduct carefully.Make surethat theinstrumentisnotdamaged.Ifany
damageoccuredduringshipment,pleasenotifyyourDealer.
EachHI95734IonSelectiveMeterissuppliedcompletewith:
•TwoSampleCuvets andCaps
•9V Battery
• Scissors
•InstructionManual
•Rigidcarryingcase
Note:save all packing material until you are sure that the instrument works correctly.
Anydefectiveitemmustbereturnedinitsoriginalpacking.

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TheHI95734isanautodiagnosticportablemicroprocessor meterthatbenefitsfromHanna’s
yearsofexperienceasamanufacturerofanalyticalinstruments.Ithastheadvancedopticalsystem
basedonaspecialtungstenlampandanarrowbandinterferencefilterthatallowsmostaccurate
andrepeatablereadings.Allinstrumentsarefactorycalibratedandtheelectronicandoptical
designminimizestheneedoffrequentcalibration.
WiththepowerfulCALCHECKvalidationfunctionyouareabletovalidategoodperformanceof
yourinstrumentatany time.Thevalidation procedureisextremelyuserfriendly.Justusethe
exclusiveHannaready-made,Nisttraceablestandardstoverifytheperformanceoftheinstrument
andrecalibrateifnecessary.
Allinstrumentsaresplashwaterproofandthelampandfilterunitsareprotectedfromdustordirt
byatransparentcup.Thismakestheinstrumentsfulfillfieldapplications.Displaycodesaidthe
userinroutineoperation.Themeterhasanauto-shutofffeaturethatwillturnofftheinstrument
after10minutesofnonuseorafter1hourifleftinthe calibrationmode .
Themeterusesanexclusivepositive-lockingsystemtoensurethatthecuvetisinthesameposition
everytimeitisplacedintothemeasurementcell.Itisdesignedtofitacuvetwithalargerneck
makingiteasiertoaddbothsampleandreagents.Thecuvetismadefromspecialopticalglassto
obtainbestresults.
TheHI95734meter measuresthefreeandtotalchlorine(Cl2)contentinwatersamples inthe
0.00to10.00mg/L(ppm)range.ThemethodisanadaptionoftheUSEPAMETHOD330.5for
wastewater,andStandardMethod4500-ClGfordrinkingwater.
Thereagentsareinpowderandliquidformandaresuppliedinpacketsandbottles.Theamountof
reagentispreciselydosedtoensurethemaximumrepeatability.
GENERAL DESCRIPTION
ABBREVIATIONS
degreeCelsius
USEnvironmentalProtectionAgency
degreeFahrenheit
milligramsperliter.mg/Lisequivalenttoppm(partpermillion)
milliliter
°C:
EPA:
°F:
mg/L:
mL:

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Range FreeCl20.00to10.00mg/L
TotalCl20.00to10.00mg/L
Resolution 0.01mg/Lfrom0.00to3.50mg/L;0.10mg/Labove3.50mg/L
Precision ±0.06mg/L @ 3.00 mg/L
Typical EMC Deviation ±0.01 mg/L
Light Source Tungstenlampwithnarrowbandinterferencefilter@525nm
Light Detector SiliconPhotocell
Method AdaptationoftheUSEPAmethod330.5andStandardMethod4500-Cl
G.ThereactionbetweenchlorineandtheDPDreagentcausesapink
tintinthesample.
Environment 0to50°C(32to122°F);max95%RHnon-condensing
Battery Type 1x9volt
Auto-Shut off After10'ofnon-usein
measurementmode ;
after1hourofnon-usein calibrationmode .
Dimensions 180x83x46mm(7.1x3.3x1.8")
Weight 290g(10oz.).
REQUIRED REAGENTS
Code Unit Description Quantity/test
HI 93701-0 Free&TotalCl2DPDPowderReagent 1packet
HI 93734B-0 Free&TotalCl2Free&TotalCl2Reagent 5mL
HI 93734C-0 TotalCl2TotalCl2Reagent 3drops
SPECIFICATIONS
Precisionishowcloselyrepeatedmeasurementsagree
witheachother. Precisionisusuallyexpressedas
standarddeviation(SD).Accuracyisdefinedasthe
nearnessofatestresulttothetruevalue.
Althoughgoodprecisionsuggestsgoodaccuracy,
preciseresultscanbeinaccurate.Thefigureexplains
thesedefinitions.
Inalaboratoryusingastandardsolutionof3.00
mg/Lchlorineandarepresentativelotofreagent,an
operatorobtainedwithasingleinstrumentastandard
deviationof0.06mg/L..
PRECISION AND ACCURACY

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Absorptionoflightisatypicalphenomenonofinteractionbetweenelectromagneticradiationand
matter.Whenalightbeamcrossesasubstance,someoftheradiationmaybeabsorbedbyatoms,
moleculesorcrystallattices.
Ifpureabsorptionoccurs,thefractionoflightabsorbeddependsbothontheopticalpathlength
throughthematterandonthephysical-chemicalcharacteristicsofthesubstanceaccordingtothe
Lambert-BeerLaw: -log I/Io= ελc d
or
A = ελc d
Where:
-log I/Io= Absorbance(A)
Io= intensityofincidentlightbeam
I= intensityoflightbeamafterabsorption
ελ= molarextinctioncoefficientatwavelength λ
c = molarconcentrationofthesubstance
d = opticalpaththroughthesubstance
Therefore,theconcentration"c"canbecalculatedfromtheabsorbanceofthesubstanceasthe
otherfactorsareknown.
Photometricchemicalanalysisisbasedonthepossibilitytodevelopanabsorbingcompoundfrom
a specific chemical reaction between sample and reagents. Given that the absorption of a
compoundstrictly depends on the wavelength of the incidentlightbeam,a narrow spectral
bandwidthshouldbeselectedaswellasapropercentralwavelengthtooptimizemeasurements.
TheopticalsystemofHanna'sHI95seriescolorimetersisbasedonspecialsubminiaturetungsten
lampsandnarrow-bandinterferencefilterstoguarantee bothhigh performanceand reliable
results.
HI95seriesBlockdiagram(opticallayout)
PRINCIPLE OF OPERATION

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Amicroprocessorcontrolledspecialtungstenlampemitsradiationwhichisfirstopticallyconditioned
andbeamedtothesamplecontainedinthecuvet.Theopticalpathisfixedbythediameterofthe
cuvet.Thenthelightisspectrallyfilteredtoanarrowspectralbandwidth,toobtainalightbeamof
intensityIoorI.
ThephotoelectriccellcollectstheradiationIthatisnotabsorbedbythesampleandconvertsit
intoanelectriccurrent,producingapotentialinthemVrange.
Themicroprocessorusesthispotentialtoconverttheincomingvalueintothedesiredmeasuring
unitandtodisplayitontheLCD.
Themeasurementprocessiscarriedoutintwophases:firstthemeteriszeroedandthentheactual
measurementisperformed.
Thecuvethasaveryimportantrolebecauseitisanopticalelementandthusrequiresparticular
attention.Itisimportantthatboththemeasurement andthe calibration(zeroing) cuvetsare
opticallyidenticaltoprovidethesamemeasurementconditions.Wheneverpossibleusethesame
cuvetforboth.Itisnecessarythatthesurfaceofthecuvetiscleanandnotscratched.Thistoavoid
measurementinterferenceduetounwantedreflectionandabsorptionoflight.Itisrecommended
nottotouchthecuvetwallswithhands.
Furthermore,inorder tomaintainthesameconditionsduringthe zeroingand themeasuring
phases,itisnecessarytoclosethecuvettopreventanycontamination.
FUNCTIONAL DESCRIPTION
1) LiquidCrystalDisplay(LCD)
2) CuvetHolder
3) Cuvetalignmentindicator
4) ON/OFFkey
5) ZERO/SETkey
6) READ/TIMERkey
7) CALCHECKkey

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KEYPADDESCRIPTION
• ON/OFF:toturnthemeteronandoff.
• ZERO/SET:thisisabi-functionalkey:presstozerothemeterpriortomeasurement,orholdthe
keyfor3secondstoselectthedesiredparameter(freeortotalchlorine).
• READ/TIMER:thisisabi-functionalkey,justpressformakingameasurement,orholdthekey
for3secondstostartapre-programmedcountdownpriortomeasurement.
• CALCHECK:thisbi-functionalkeyallowstoperformvalidationoftheinstrumentjustpressing
theCALCHECKkey,orholdthekeyfor3secondstoenterthe
calibrationmode .
OPERATINGMODES
•
Measurement mode: defaultoperationmode,enablesbothvalidationandmeasurement.
• Calibrationmode: maybeentered bykeepingCALCHECKpressedforthreeseconds(the“CAL”
iconappears),itenablescalibrationoftheinstrument.
DISPLAYELEMENTSDESCRIPTION
1) fourdigitmaindisplayarea.
2) CAL:appearswhentheinstrumentoperatesinthe
calibrationmode.
3) theMonth andDay icons appear abovethe number of monthand day when a dateis
displayed.
4) theblinking“Battery”iconappearswhenthebatteryvoltageisgettinglow.

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Thisprompt appears for 1 second each time the instrument is
turnedon.
Theparametercode,“734f”forfreechlorineor“734t”fortotal
chlorine,indicatesthatthemeterisinareadystateandzeroing
canbeperformed.
SamplinginProgress.Thisflashingpromptappearseachtimethe
meterisperformingameasurement.
Thisindicatesthatthemeterisinazeroedstateandmeasurement
canbeperformed.
Lightoverrange:thecuvetisnotinsertedcorrectlyandanexcess
ambientlight is reaching the detector. Ifthecoveris properly
installed,thencontactyourdealerorthenearestHannaCustomer
ServiceCenter.
Theblinking"BAT"indicatesthatthebatteryvoltageisgettinglow
andthebatteryneedstobereplaced.
Thisindicatesthatthebatteryisdeadandmustbereplaced.Once
thisindication is displayed,themeter will lock up.Changethe
batteryandrestart.
“Configuration”: this indicates that the meter has lost its
configuration.ContactyourdealerorthenearestHannaCustomer
ServiceCenter.
CALIBRATIONMODE MESSAGES
ThedateofthelastcalibrationappearsontheLCDeachtimethe
calibrationmode isentered.Ifcalibrationisperformedforthefirst
time,“F.CAL”appears.
Thisindicatesthatthefactorycalibrationisselected.
GUIDE TO DISPLAY CODES

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Theflashingdigitsindicatethat:
1)themonthcanbeset
2)thedaycanbeset
“Storage”:this prompt appears for1secondat the end of the
calibrationprocedure,to indicate thatthecalibration datahas
beenstored.
“Error”:theconcentrationofthecalibrationsolutionusedisnotcorrect.
Repeatthecalibrationprocedurewiththerightstandardsolution,
andverifyitisnotexpired.Ifthecalibrationprocedurefailsagain,
contactyourdealerorthenearestHannaCustomerServiceCenter.
ERROR MESSAGES
a)onzeroreading
Thisindicatesthatthezeroingprocedurefailedduetoalowsignal-to-
noiseratio.InthiscasepressZEROagain.
“NoLight”:theinstrumentcannotadjustthelightlevel.Pleasecheck
thatthesampledoesnotcontainanydebris.
“LightLow”:thereisnotenoughlighttoperformameasurement.
Pleasecheckthepreparationofthezerocuvet.
“LightHigh”:thereistoomuchlighttoperformameasurement.
Pleasecheckthepreparationofthezerocuvet.
b)onsamplereading
Thereistoomuchlightforthesamplemeasurement.Pleasecheckif
therightsamplecuvetisinserted.
“Inverted”:thesampleandthezerocuvetareinverted.
“Zero”:azeroreadingwasnottaken.Followtheinstructioninthe
measurementprocedureforzeroingthemeter.

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Underrange.Ablinking"0.00"indicatesthatthesampleabsorbs
lesslightthanthezeroreference.Checktheprocedureandmake
sureyouusethesamecuvetforreference(zero)andmeasurement.
A flashing value of the maximum concentration indicates an
overrangecondition.Theconcentrationofthesampleisbeyond
theprogrammedrange:dilutethesampleandre-runthetest.
Aflashingvaluelowerthanthemaximumconcentrationindicates
a lowsignal-to-noiseratiocondition.Inthiscaseaccuracyofthe
resultisnotguaranteed.Repeatthemeasurementprocedure.
Theinstructionslistedbelowshouldbecarefullyfollowedduringtestingtoensurebestaccuracy.
• Colororsuspendedmatterinlargeamountsmay
cause interference, therefore these should be
removedbytreatmentwithactivecarbonandby
priorfiltration.
• Foracorrectfillingofthecuvet:theliquidinthe
cuvetformsaconvexityonthetop;thebottomof
thisconvexitymustbeatthesamelevelofthe10
mLmark.
• Itisimportantthatthesample doesnotcontain
anydebris.Thiswouldcorruptthereading.
• Each time the cuvet is used, the cap must be
tightenedtothesamedegree.
• Wheneverthecuvetisplacedintothemeasurement
cell,itmustbedryoutside,andcompletelyfreeof
fingerprints,oilordirt. Wipeit thoroughlywith
HI731318(tissueforwipingcuvets,seechapter
ACCESSORIES)oralint-freeclothpriortoinsertion.
GENERAL TIPS FOR AN ACCURATE MEASUREMENT

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• Inordertomeasureexactly5mLofreagentwiththe5mLsyringe:
(a) pushtheplungercompletelyintothesyringeandinsertthetipintothereagentbottle.
(b) pulltheplungerupuntiltheloweredgeofthesealisexactlyonthe5mLmark.
(c) takeoutthesyringeandcleantheoutsideof thesyringetip.Besurethatno dropsare
hangingon the tipofthesyringe, if soeliminatethem.Then, keeping the syringein
verticalpositionabovethecuvet,pushtheplungercompletelydownintothesyringe.Now
theexactamountof5mLhasbeenadded tothecuvet.
• Properuseofthedropper:
(a) togetgoodreproducibleresults,tapthedropperonthetableforseveraltimesandwipe
theoutsideofthedroppertipwithacloth.
(b) alwayskeepthedropperbottleinaverticalpositionwhiledosingthereagent.
• Properuseofthepowderreagentpacket:
(a) usescissorstoopenthepowderpacket;
(b) pushtheedgesofthepackettoformaspout;
(c) pour outthecontentofthepacket.
(a) (b) (c)
(a) (b)

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(a) (b) (c)
• Shaking thecuvet cangenerate bubbles inthe sample,causing higher readings.To obtain
accuratemeasurements,removesuchbubblesbyswirlingorbygentlytappingthevial.
• Donotletthereactedsamplestandtoolongafterreagentisadded,oraccuracywillbelost.
• Itispossible totakemultiplereadingsinarow, butitisrecommendedtotakea newzero
readingforeachsampleandtousethesamecuvetforzeroingandmeasurement.
• Afterthereadingitisimportanttodiscardimmediatelythesample,otherwisetheglassmight
becomepermanentlystained.
• Allthereactiontimesreportedinthismanualarereferredto20°C(68°F).Asageneralruleof
thumb,theyshouldbedoubledat10°C(50°F)andhalvedat30°C(86°F).
• Inordertomaximizeaccuracy,priortoameasurementfollowthevalidationproceduretobe
surethattheinstrumentisproperlycalibrated.Ifnecessary,calibratetheinstrument.

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OPERATIONAL GUIDE
• TurnthemeteronbypressingON/OFF.
• WhentheLCD displays“734f”or“734t”itis
ready.Thedisplaycodethatappearsistheone
ofthelastselectedparameter.
• keepZERO/SETpressedtochangeparameter.
Theparameter code will changeeverythree
seconds,until the key is released. Select the
programforfreechlorine“734f”ortotalchlorine
“734t”.
• Afterthedesired parametercode appearson
the display, perform either MEASUREMENT,
VALIDATION, or CALIBRATION PROCEDURE
followingtheinstructionsreportedintherelated
chapter.
Code Parameter
734f FreeChlorine
734t TotalChlorine
or
•ImportantNote:FreeandTotalChlorinehavetobemeasuredseparatelywithfreshunreacted
samplesifbothvaluesarerequested.

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• Select the parameter code for free chlorine
“734f” or total chlorine “734t” by holding
ZERO/SET(seepage14).
• Addtothecuvet5mLofHI93734B-0reagent
bymeansofthe5mLsyringe.
Note: in order to measure exactly 5 mL of
reagentwiththesyringe,followtheinstructions
onpage12.
• Fillthecuvetuptothe10mLmarkwith5mL
of unreacted sample, using the 3 mL plastic
pipette.
Note: rinse the 3 mL plastic pipette several
timeswithsamplebeforeaddingittothecuvet.
• Replace the cap and shake gently for some
seconds.
• Placethecuvetintotheholderandensurethat
thenotchonthecapispositionedsecurelyinto
thegroove.
• Press ZERO/SET and “SIP” will blink on the
display.
• Afterafewsecondsthedisplaywillshow
“-0.0-”.Themeterisnowzeroedandreadyfor
measurement.
• Removethecuvet.
MEASUREMENT PROCEDURE

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• Onlyinthecaseoftotalchlorinemeasurement,
add 3 drops of HI 93734C-0 reagent to the
cuvet.
• Forbothfreeandtotalchlorine,addthecontent
of one packet of HI 93701-0 Free Chlorine
reagent.Replacethecapandshakegentlyfor
20seconds(or 2minutesincaseofseawater
analysis).
• Replacethe cuvet intotheholderandensure
thatthenotchonthecapispositionedsecurely
intothegroove.
• HoldREAD/TIMERforthreeseconds.Thedisplay
willshowthecountdownpriortomeasurement.
Alternatively,waitfor:
FreeChlorine: TotalChlorine:
1minute 2minutesand30seconds
ThenpressREAD/TIMER.
In both cases “SIP” will blink during
measurement.
• Theinstrumentdirectlydisplaysconcentration
inmg/LoffreeortotalchlorineontheDisplay.
or
INTERFERENCES
Bromine(positiveerror) OxidizedManganeseandChromium(positiveerror)
Chlorinedioxide(positiveerror) Ozone(positiveerror)
Iodine(positiveerror)
Alkalinityabove250mg/LCaCO3oracidityabove150mg/LCaCO3willnotreliablydevelopthe
fullamountofcolororitmayrapidlyfade.Toresolvethis,neutralizethesamplewithdilutedHCl
orNaOH.
Incaseofwaterwithhardnessgreaterthan500mg/LCaCO3,shakethesampleforapproximately
2minutesafteraddingthepowderreagent.
forTotal
Chlorine
only
or

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VALIDATION PROCEDURE
• Select the parameter code for free chlorine
“734f” or total chlorine “734t” by holding
ZERO/SET(seepage14).
• PlacetheCALCHECKStandardCuvetAintothe
holderandensurethatthenotchonthecapis
positionedsecurelyintothegroove.
• PressZEROand“SIP”willblinkonthedisplay.
• Afterafewsecondsthedisplaywillshow
“-0.0-”.Themeterisnowzeroedandreadyfor
validation.
• Removethecuvet.
• Placethe CAL CHECK Standard HI95734-11
Cuvet Binto the holder and ensure that the
notchonthecapispositionedsecurelyintothe
groove.
• PressCAL CHECK and “SIP” willblinkduring
measurement.
• Waitforafewsecondsandthedisplaywillshow
thevalidationstandardvalue.
Thereadingshouldbe withinspecificationsas
reportedontheCalCheckStandardCertificate.
Ifthevalueisfoundoutofspecifications,please
checkthatthecuvetsarefreeoffingerprints,oil
ordirtandrepeatvalidation.Ifresultsarestill
foundoutofspecificationsthenrecalibratethe
instrument.
Usethevalidationproceduretoensurethattheinstrumentisproperlycalibrated.
Warning:donotvalidateorcalibratetheinstrumentwithstandardsolutionsotherthantheHanna
CALCHECKStandards,otherwiseerroneousresultswillbeobtained.

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CALIBRATION PROCEDURE
• Select the parameter code for free chlorine
“734f” or total chlorine “734t” by holding
ZERO/SET(seepage14).
• Enterthe
calibrationmode byholdingCALCHECK
forthreeseconds.
• Thedateofthelastcalibration appears(e.g.:
month“01”,day“08”). “F.CAL”means that
thefactorycalibrationisselected.
Note: at this point it is possible to reset the
instrumenttorestoreFACTORYCALIBRATION,
seeinstructionspage20.
• PlacetheCALCHECKStandardCuvetAintothe
holderandensurethatthenotchonthecapis
positionedsecurelyintothegroove.
• PressZEROand“SIP”willblinkonthedisplay.
• Afterafewsecondsthedisplaywillshow
“-0.0-”.Themeterisnowzeroedandreadyfor
calibration.
• Removethecuvet.
• Placethe CAL CHECKStandardHI 95734-11
Cuvet Binto the holder and ensure that the
notchonthecapispositionedsecurelyintothe
groove.
CALIBRATION PROCEDURE
Note:itispossibletointerruptcalibrationprocedureatanytimebypressingON/OFF.
Warning:donotvalidateorcalibratetheinstrumentwithstandardsolutionsotherthantheHanna
CALCHECKStandards,otherwiseerroneousresultswillbeobtained.
or

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or
• PressREAD/TIMERand“SIP”willblinkduring
measurement.
• Theinstrumentwillshowforthreesecondsthe
CalCheckstandardvalue.
Thenthedateoflastcalibration(e.g.:“01.08”)
appearsonthedisplay,or“01.01”ifthefactory
calibration was selected. In both cases the
numberofthemonthisblinking,readyfordate
input.
Note:ifthedisplayshows“ERR”thecalibration
procedurefailed.VerifythatbothCAL CHECK
StandardsHI95734-11 Cuvets,AandB,are
freefromfingerprintsordirtandthattheyare
insertedcorrectly.
DATE INPUT
• KeepREAD/TIMERpressedtoscrolltothedesired
monthnumber(01-12).
• Whenthe correct month has been set, press
ZEROtoconfirm.Nowthedisplaywillshowthe
daynumberblinking.KeepREAD/TIMERpressed
toscrolltothedesireddaynumber(01-31).
Note: it is possible to change from day to
month andviceversabypressingZERO.
• When both the day and month have been
selected,holdCALCHECKforthreesecondsto
storedateandcalibrationvalues.Theinstrument
willshowforonesecond“Stor”,toconfirmthat
thenewcalibrationdatahasbeenaccepted.
• Theinstrumentwillreturnautomaticallytothe
measurementmodeby displayingtheparameter
code(“734f”or“734t”)ontheLCD. or

20
Batteryreplacementmustonlytakeplaceinanon-
hazardousarea.
Simplyslideoff thebatterycoveronthebackof
themeter.Detachthebatteryfromtheterminals
andattachafresh9Vbatterywhilepayingattention
tothecorrectpolarity.Insertthebatteryandreplace
thecover.
9V
SLID
E
OFF
BATTERY REPLACEMENT
or
FACTORYCALIBRATIONRESET
Itispossibletorestorefactorycalibration:
• Enterthe
calibrationmode byholdingCALCHECK
forthreeseconds.
• HoldZERO/SETfor10seconds.Thedisplaywill
showfor2seconds“F.CAL”andtheparameter
code("734f"or“734t”)appears.Thefactory
calibrationis automaticallyrestored andthe
instrumentisreadyformeasurement.