Metal Samples MS2901E User manual

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MS2901E
High Resolution ER 4-20mA HART Transmitter
Operator’s Manual
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Metal Samples Company
A Division of Alabama Specialty Products, Inc.
152 Metal Samples Rd., Munford, AL 36268 Phone: [phone] Fax: [phone]
E-mail: [email protected] Internet: www.metalsamples.com

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Table of
Contents
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I.Introduction..............................................................................................................................................1
A.GeneralDescription...................................................................................................................1
B.PrinciplesofOperation..............................................................................................................1
C.TechnicalSpecifications.............................................................................................................3
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II.InstallationandOperation.......................................................................................................................4
A.ReceivingtheMS2901ETransmitter.........................................................................................4
B.Installation.................................................................................................................................4
1.PhysicalMountingandProbeConnection...................................................................4
a.Direct‐ProbeMounting......................................................................................5
b.RemoteMounting..............................................................................................5
2.CurrentLoopConnection.............................................................................................6
a.MakingConnections.........................................................................................6
b.Grounding.........................................................................................................6
c.WiringforaSafeAreaInstallation....................................................................6
d.HARTConnectionforaSafeAreaInstallation...................................................7
e.WiringforaHazardousAreaInstallation...........................................................8
f.WiringwithHARTatHazardouslocations..........................................................9
3.SetupandOperation.....................................................................................................10
a.ProbeSelectionSwitches..............................................................................10
b.TestingtheCurrentLoop..............................................................................11
i.Calibration...............................................................................................11
ii.Testingloopoutputzero(4mA)andspan(20mA).................................12
iii.TestingtheMS2901EwiththeMeterProver..........................................12
c.InterpretingData............................................................................................13
i.MetalLoss................................................................................................13
ii.CalculatingCorrosionRate.......................................................................14
d.Commissioning..............................................................................................16
C.Maintenance............................................................................................................................17
D.HARTCommunicationandDeviceDescriptor..........................................................................18
E.TheHARTModem.....................................................................................................................33
F.Troubleshooting........................................................................................................................37
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III.ServiceandWarrantyInformation.......................................................................................................38
A.Warranty...................................................................................................................................38
B.ObtainingServiceandReturningtheInstrumentforRepair....................................................38
C.InstrumentRepairForm...........................................................................................................39
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AppendixA–RevisionHistory...................................................................................................................40
AppendixB–HazardousAreaCertificationDetails...................................................................................41
AppendixC–ControlDrawing(HazardousAreaWiringDiagram)............................................................48
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1
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I.Introduction
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A.GeneralDescription
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TheMS2901Eisahigh‐resolutionmeterdesignedtotransmitcorrosion(metalloss)datafromanElectrical
Resistance(ER)probetoaplantcontrolsystemorotherrecordingdevice.TheMS2901Eutilizestraditional
4‐20mAcurrentloopcommunicationandHARTDigitalTransmission.Itisloop‐poweredwithbuilt‐in
isolator,soitrequiresonlyatwo‐wireinterface.Thisresultsinasimpleandlow‐costinstallation.Theuse
ofthe4‐20mAprotocolalsoallowstheMS2901Etobeplacedgreatdistancesfromthecontrolsystemor
recorderwhilemaintaininggoodnoiserejection.Practicalcurrentloopdistancescanbemanythousands
offeet(seepages6and7forexactspecifications).Also,HARTdigitaltransmissionhelpstoconnectthe
transmittertoHARTSystem/PC/Handheld.
TheMS2901EiscompatiblewithalltypesofMetalSamplesERprobes,aswellasanystandardERprobe
fromothermanufacturers.Unlikecompetitors’products,theMS2901ETransmitterdoesnotrequire
factorymodificationtoaccommodatedifferentprobetypes.Theprobetypecanbeeasilychangedatany
timeusingtheon‐boardprobeselectionswitches(seepage9.)
TheMS2901Eisavailableasdirect‐mount(standard)orremote‐mount.Inthedirect‐mountversionthe
MS2901EismounteddirectlytotheERprobe.Thisoptionoffersthesimplestinstallationandminimizes
noiseproblems.Theremote‐mountoptionallowstheMS2901Etobemountedindependentlyfrom(butin
closeproximityto)theERprobe.Itisthenconnectedtotheprobeviaashortprobecable.(Seepage5for
mountingdiagramsandspecifications.)
B.PrinciplesofOperation
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TheMS2901EoperatesontheElectricalResistance(ER)techniqueandisusedinconjunctionwithanER
probe.TheERprobeutilizesaresistivesensingelementmanufacturedfromthematerialofinterest(ora
closeapproximation)whichisexposedtoacorrodingenvironment.ThisiscalledtheExposedorCorroding
Element.TheresistanceoftheExposedElementisdirectlyrelatedtoitsthickness,soastheelement
corrodestheresultinglossofmetalcausesaproportionalincreaseintheelement’sresistance.Theprobe
alsocontainsaninternalReferenceElementwhichisusedtocompensatefortheinfluencesof
temperatureontheExposedElement.
TheMS2901EisdesignedtoworkwithanystandardERprobe,butitisrecommendedthatCylindricaland
LargeFlushtypeprobesbeusedtoensureoptimumperformance.Theirphysicaldesignplacesthe
ReferenceElementincloserproximitytotheExposedElementcomparedtootherprobetypes,providing
moreeffectivetemperaturecompensationandthusreducingtheeffectsofthermalnoise.
Becausetheyaredesignedtocorrode,ERprobesaresacrificialinnature.EachERprobewillhaveafinite
lifethatisbasedontheelementthickness.ERprobesareavailableinanumberofgeometriesand
thicknessesdesignedtosuitawidevarietyofapplications.Table1liststhecommonERelementoptions
availablefromMetalSamplesandtheeffectivelifeofeach.

2
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ElementTypeCompatibilityThicknessProbeLife
(Span)
TubularLoopCompatible
42
84
WireLoopCompatible
4010
8020
Flush(Small)Compatible
42
84
2010
CylindricalPreferred
105
2010
5025
Flush(Large)Preferred
52.5
105
2010
4020
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Table1.StandardERProbeElements
TheMS2901EmeasuresanERprobeutilizingahigh‐resolution,16‐bitmeasurement.Thisallowsthe
MS2901Etodetectmuchsmalleramountsofmetalloss,thusrespondingfastertocorrosioneventsand
upsets(comparedtotraditionalERmeters.)At16‐bitresolutiontheMS2901Ecanmeasuremetalloss
amountsassmallas0.0015%oftheprobelife.
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MetallossreadingstakenbytheMS2901Eareconvertedtoalinearized4‐20mAcurrentloopoutput.
The4‐20mAsignalcanbefedintoaplantcontrolsystemorotherdevicesandscaledaccordinglyto
reflectmetalloss.Thencorrosionratescanbecalculatedbasedonthemetallossdataovertime.Thisis
coveredinmoredetailonpages11and12.MoreinformationonERprobes,theirtheory,selection,and
usecanbefoundonourwebsiteat http://www.alspi.com/erintro.htm.
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3
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C.TechnicalSpecifications

PhysicalData
InstrumentWeight: 5.25lb.(2.38Kg)
TotalWeightw/Accessories:7.31lb.(3.31Kg)
InstrumentDimensions:9.0"Hx5.3"Wx5.0"D
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(22.86cmHx13.46cmWx
12.70cmD)
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OperatingTemperature:‐40°to158°F(‐40°to70°C)
StorageTemperature:‐40°to176°F(‐40°to80°C)
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EnclosureMaterial:CastAluminum(Copper‐Free)
MountingSpecifications:Directprobemountor
Remotemount
(Uptoa2.5”(6.35cm)Dia.pole)
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PerformanceData
MeasurementType:ERmeasurementusinganystandardERprobetype
(WireLoop,TubeLoop,Cylindrical,Flush,Strip,etc.)
Range:0‐100%ofprobelife
Resolution:0.0015%ofProbeLife(16‐bit)
CycleTime:1Minute
ElectricalData
Connection:4to20mAwithHART,2Wire
PowerRequirements:11to28VDC
CurrentConsumption:4to22.5mA
Maximum20mAwithoutalarm/22.5mAwithalarm
ElectricalConnection:½”NPTentrywithExGland
¾”orotherentriesareavailablewithadaptors*
MaximumProbeCableDistance:30ft(9.1m)
OutputData
OutputSignal:4‐20mAoutputwithHARTprotocol
AlarmSignal:‐CurrentOutputConfigurable
‐Digitalinterface
Load:‐min.250OhmsforHARTCommunication
HazardousLocationCertifications–IntrinsicSafety
EuropeandWorldwideExdb[iaGa]IICT6….T4Gb
(ATEXandIECEx)Extb[iaDa]IIICT85°C…T130°CDb
‐40°C≤Tamb≤+70°C
ATEXCertificateNo:ITS14ATEX27981XIECEx
CertificateNo:IECExITS14.0010X
USAandCanadaClassI,Zone1,AExdb[iaGa]IICT6….T4Gb
(ETL)ClassI,Division2,GroupsA,B,C&D,T6…T4

HazardousLocationCertifications–Enclosure
CaseSpecifications:ExplosionProof(FM,CSA,UL)
IP66,NEMA4X,7BCD,9EFG
IncludedAccessories(Direct‐MountModel)
MeterProver,OperationsManual
IncludedAccessories(Remote‐MountModel)
MeterProver,OperationsManual,ProbeCable,MountingHardwareKit

4

II.InstallationandOperation

A.ReceivingtheMS2901ETransmitter

ChecktheMS2901ETransmitterforanyshippingdamagewhenitisfirstreceived.WhentheMS2901E
isunpacked,verifythatthefollowingitemsareincluded:

MS2901ETransmitter
MeterProver
User’sManual
ProbeCable&MountingHardware(optional,forremote‐mountonly)
Intheeventofshippingdamage,quantityshortage,ormissingitems,itisrecommendedthattheevent
isdocumentedimmediatelyandthatdigitalphotographsaretaken.Anyshortagesormissingitems
shouldbereportedtoMetalSamplesimmediately.Intheeventofshippingdamage,aclaimshouldbe
openedwiththeresponsiblecarrier.
B.Installation

Warning:Donotopenwhenanexplosiveatmosphereispresent.Potentialelectrostaticcharginghazard.
Seeinstructions.Referusemanualforinstallationinstructionsandmaximumelectricalinput&output
parameters.
Attention:nepasouvrirenprésenced'uneatmosphèreexplosive.Risquepotentieldecharge
électrostatique.Voirlesinstructions.Consultezlemanueld'utilisationpourlesinstructionsd'installation
etlesparamètresd'entréeetdesortieélectriquesmaximum.

InstallationoftheMS2901ETransmitterinvolvesthefollowingsteps:
1. PhysicalMounting
2. ElectricalConnection
3. SetupandProgramming

1.PhysicalMountingandProbeConnection

WhenselectingalocationtomounttheMS2901Eitisimportanttoconsiderthesurrounding
environment.Toensureproperoperation:
DonotmounttheMS2901Einalocationthatexceedsitsoperatingtemperature.
AvoidmountingtheMS2901Enearsourcesofstrongelectricalnoise.
Ensurethatthereissufficientclearanceforinstallationandtoopenthetransmittercover
afterwards.
a.Direct‐ProbeMounting
TheMS2901Eisdesignedfordirect‐probemountingwhicheliminatestheneedforadditionalhardware
andtransmitter‐to‐probecabling.Thisgreatlysimplifiesinstallation,reducescosts,andminimizes
electricalnoisethatcanbecoupledontoprobecablingfromnearbyelectricalequipment.

BeforemountingtheMS2901E,firstensurethattheprobeisinstalledproperlyandsecurely.During
installationitisimportantthatyoudonotapplyexcessiveforceontheprobeorseals,asdoingsocould
breakthesealandresultinsystemleakage.

5

TomounttheMS2901E:
1. Alignthekeywaysofthetransmitterandprobeconnectors.
2. Insertthetransmitterconnectorplugfullyintotheprobeconnectorreceptacle.
3. Securethetransmittertothetopoftheprobebytighteningthecouplingnut.
NOTE:Hand‐tightissufficient.Donotover‐tightenthecouplingnut.
NOTE:Neverforcetheconnectorstomate.Ifthereisresistance,stopandcheckforbentpinson
theprobeandforforeignmaterialinthefemalesocketsofthetransmitterconnector.Gently
straightenanybentpinsandclearanyforeignmaterialthatmaybefound.











AlignKey




Insert 
Connector 
Tighten
CouplingNut


123

Figure2.MS2901EDirectMountInstallation
b.RemoteMounting
Whenitisnotpracticaltodirect‐probemounttheMS2901Etransmitter,theunitcanberemote
mountedinstead.Inthiscasetheinstrumentismountedtoaseparatemountingpoleusingthe
optionalRemoteMountingHardwareKit.ThetransmitteristhenconnectedtotheERprobeviathe
probeextensioncable.




















Figure3.RemoteMountInstallation

6

2.CurrentLoopConnection

a.MakingConnections
TheMS2901Ecurrentloopconnectionwiringentersthetransmitterthroughthe1/2"femaleNPT
conduitportshowninFigure4below.PleaserefercontroldrawingforwiringandTerminal
identification.

CAUTION:Whenusedinahazardousarea,theconduitorcableconnectionsmustbemadeinsuch
awaythatallhazardousarearequirementsaremet.CableGlandsandblankingplugsmustbe
certifiedforprotectiontypes‘Exdb’or’tb’anditshouldberatedforIP66.
ATTENTION:Lorsqu'ilssontutilisésdansunezonedangereuse,lesconnexionsdesconduitsou
descâblesdoiventêtreréaliséesdemanièreàcequetouteslesexigencesrelativesauxzones
dangereusessoientsatisfaites.Lespresse‐étoupesetlesobturateursdoiventêtrecertifiéspour
lestypesdeprotection«Exdb»ou«tb»etdoiventêtreclassésIP66.



ProbeConnector
StemorProbeCable






1/2”FNPTConduitPortfor
FieldWiringEntry
Figure4.MS2901EcurrentLoopConnector

ThemaximumpermissiblelengthofthecurrentloopwiringbetweentheMS2901ETransmitterand
thecontrolsystemisdeterminedbythecontrolsystemsupplyvoltage,theelectricalresistanceofthe
currentloopcableandtheloadofthecontrolsysteminput.IftheTransmitteristobeinstalledina
safearea,refertosectionc.WiringforaSafeAreaInstallationfordetails.IftheTransmitteristobe
installedinahazardousarea,refertosectiond.WiringforaHazardousAreaInstallation.

b.Grounding

TheMS2901Eenclosureisgroundedinternallythroughthewiringharness,butanadditional,external
groundingterminalisprovidedaswell.Theenclosureshouldbegroundedproperlyusingtheexternal
groundingterminaltoensuresafeoperation.

c.WiringforaSafeAreaInstallation


Forbasicsafeareawiringinformationrefertothecircuitdiagramshownonpage19.Usethefollowing
equationtodeterminemaximumpermissiblecablelength:

𝐷 󰇛𝑉
10󰇜
󰇛4∗10󰇜󰇛𝑅󰇜



7

Where:
D=Max.cablelengthinfeet.
VS=Powersupplyvoltage.
R=Cableresistanceinohmsper1000feet.

Example:
VS=24Volts
R=16.1(22AWGcable)
𝐷 󰇛24 10󰇜
󰇛4∗10󰇜󰇛16.1󰇜21,739 𝐹𝑒𝑒𝑡



d.HARTConnectionforaSafeAreaInstallation


MetalSamplesMS2901EsupportsHARTcommunicationprotocol.HARTisanacronymforHighwayAddressable
RemoteTransducer.TheHARTprotocolmakesuseoftheBell202FSKstandardtosuperimposedigitalsignalsat
alowlevelontopofthe4‐20mASignal.Thisenablestwo‐waycommunicationandmakesitpossiblefor
additionalinformationbeyondjustthenormalprocessvariabletobecommunicatedtoandfromafield
instrument.
MS2901EcanbeconnectedtoHARTmodemtocommunicatewiththecomputerinasafearea.Connectthe
modemacross250Ohmsresistorinlinewithcurrentloopsupplyasshowninfigure.Anycertifiedhandheld
terminalcanbeconnectedtothecurrentloopsupplyoftheinstrumenttocommunicateandaccessthe
variablesandtheprobelifeandotheritemscanbesetfromremoteterminal.(ReferHandheldequipment’s
connectiondetailsforproperconnectiondetails).
Duetothesensitivenatureofcorrosionmeasurement,itisimportanttoprovidegoodelectricalisolation
betweentheI/Osystem/powersupplyandeach4‐20mA/HARTsignalfromMS2901E.MetalSamples
recommendsusingisolatororisolatedI/ocardtoconnecttothePLC/DCSHARTconnections
Forallothergeneralapplications,asignalconditionercapableofrepeatingthe4‐20mA/HART
signalsandprovidingatleast500Vofisolationmustbeused.Ifyouareusing





8

e.WiringforaHazardousAreaInstallation


CAUTION:Thissectionprovidesgeneralguidelinesforhazardousareawiring.However,regardlessof
anythingstatedhere,theMS2901Emustbeinstalledinfullcompliancewiththecontroldrawing
locatedonpage18andallofthelocalarearequirements.
ATTENTION:Cettesectionfournitdesdirectivesgénéralespourlecâblageenzonedangereuse.
Cependant,indépendammentdetoutcequiestindiquéici,leMS2901Edoitêtreinstallé
conformémentauschémadecontrôlesituéàlapage18etàtouteslesexigenceslocales.


Wheneveranelectricallydrivensensorormeasuringdeviceisusedinapotentiallyexplosive
environmentthemeasuringsystemmustbeinstalledinsuchawaythatelectricalenergyiseither
effectivelyisolatedfromtheexplosiveenvironment(viaexplosive‐proofcontainers,cableconduits,
etc.)ortheamountofelectricalenergyproducedinthehazardousareamustbelimitedtoa
permittedlevel.

LimitingelectricalenergyisthemostpracticalmethodofprotectingtheMS2901Emeasuringsystem
whentheTransmitterisinstalledinahazardousarea.IntheMS2901Esystem,electricalenergylimits
aremaintainedusingapowersupplywithUmof28Vinstalledinthe4‐20mAcurrentloopper
standardpractice.Thevoltageshallbemaintainedallthetimeinaccordancewiththeguidancegiven
inIEC60079‐14.

Caution:IngeneralSafetybarriersarenotnecessarybutwhenasafetybarrierisusedwiththe
MS2901Esystem,thecurrentloopcablemustbeconnectedtothebarrier’shazardousareaterminals
andthebarrieroutputvoltageshouldnotexceed28Vatanycircumstances.Allotherconnections
mustbemadetothebarrier’ssafeareaterminals.
ThetypeofrepeatersafetybarrieremployedintheMS2901Esystemdependsonthespecific
classificationofthehazardousenvironmentinquestion.MetalSampleswillprovide,uponrequest,
assistanceandtechnicaladviceintheselectionofarepeatersafetybarrieroritsequivalent.

ThemaximumlengthofthecurrentloopcablethatconnectstheMS2901ETransmittertothe
repeatersafetybarrierisasfollows:


Example:
17.5Volts
22AWGCable=5,434feetmaximum
16AWGCable=21,788feetmaximum

CAUTION:Forhazardousareainstallations,themaximuminductanceandcapacitanceoftheloop
wiringbetweenthesafetybarrierandthetransmittercannotexceedtheentityparametersofthe
selectedbarrier.
ATTENTION:Pourlesinstallationsenzonedangereuse,l'inductanceetlacapacitémaximalesdu
câblagedelaboucleentrelabarrièredesécuritéetletransmetteurnepeuventpasdépasserles
paramètresd'entitédelabarrièresélectionnée.




9

f.WiringwithHARTatHazardouslocations

NoadditionalisolatorsarenecessarytouseMS2901Einhazardouslocations.Pleaseensurethatthe
maximumvoltageappliedtotheinstrumentshouldbebeloworequaltoUm=28V.

Anycertifiedhandheldterminalcanbeconnectedtothecurrentloopsupplyoftheinstrumenttocommunicate
andaccessthevariablesandtheprobelifeandotheritemscanbesetfromremoteterminal.(ReferHandheld
equipment’sconnectiondetailsforproperconnectiondetails).






































10

3.SetupandOperation

a.ProbeSelectionSwitches
HousedwithintheMS2901Eenclosureareprobeselectionswitcheswhichallowtheinstrumenttobe
setforanystandardERprobetype.Theyalsoallowtheinstrumenttobeplacedintoseveraltest
modeswhichoutputfixedvalues,allowingverificationofthecurrentloopconnectionandDCS
program.


Figure5.ConnectorandSwitchDetails


Setting
Switch
1
Switch
2
Switch
3
Switch
4
Operating
Positions
Wire Loop Off (↓)On (↑) On (↑) Off (↓)
Tube Loop/Flush On (↑) Off (↓)On (↑) Off (↓)
Cylindrical*Off (↓)Off (↓)On (↑) Off (↓)
Test
Positions
4mA Output On (↑) On (↑) Off (↓)Off (↓)
20mA Output Off (↓)On (↑) Off (↓)Off (↓)
4-20mA Sweep On (↑) Off (↓)Off (↓)Off (↓)
Table2.ProbeSwitchSettings
*Cylindricalprobesettingisillustrated.

ProbeSelectionSwitch
(Seedetailbelow)
4‐20mACurrent
L
oop

Co
nn
ecto
r
ProbeCableConnector

11

b.TestingtheCurrentLoop
i.Calibration

TheMS2901Eisfullycalibratedwhenshippedfromthefactory.Thecalibrationsettingsarefixedto
avoidaccidentalchangewhichcouldresultinerroneousdata.Ingeneralnofieldcalibrationis
required.However,itisimportanttotesttheMS2901Euponinstallation,andduringperiodic
maintenanceinspections,toensuretheunitisoperatingproperly.Followtheprocedureasbelow,if
calibrationbecomesabsolutenecessary.

Note1:Notedowntheswitchsettingsbeforeproceedingtothebelowprocedure.

1) 4.00mACalibration
a. Powerdowntheinstrument
b. TurnOffSwitch1,2and3
c. TurnOnSwitch4
d. ConnectmeterinseriestotheinstrumenttomeasurecurrentinmA.
e. Power‐uptheinstrument
f. ChecktheLoopCurrent,Nocalibrationnecessaryifthemeterreads4.00mA,if
notproceedbelow.
g. Toincreasetheloopcurrentinstepsof0.025mA,toggletheSwitch‐2toUpand
Down.EachTogglewillincreaseloopcurrentby0.025mA
h. Todecreasetheloopcurrentinstepsof0.025mA,toggletheSwitch‐3toUpand
Down.EachTogglewilldecreaseloopcurrentby0.025mA
i. Ensurecurrentreadingisequalto4.00mA.
j. TurnOffSwithc‐4.Waitforasecond
k. TurnoffthePower.

2) 20.00mACalibration
a. Powerdowntheinstrument
b. TurnOffSwitch2and3
c. TurnOnSwitch1and4
d. ConnectmeterinseriestotheinstrumenttomeasurecurrentinmA.
e. Power‐uptheinstrument
f. ChecktheLoopCurrent,Nocalibrationnecessaryifthemeterreads20.00mA,if
notproceedbelow.
g. Toincreasetheloopcurrentinstepsof0.025mA,toggletheSwitch‐2toUpand
Down.EachTogglewillincreaseloopcurrentby0.025mA
h. Todecreasetheloopcurrentinstepsof0.025mA,toggletheSwitch‐3toUpand
Down.EachTogglewilldecreaseloopcurrentby0.025mA
i. Ensurecurrentreadingisequalto20.00mA.
j. TurnOffSwithc‐4andwaitforasecond
k. TurnoffthePower.
Nowthenewcalibrationvaluesregisteredinthenon‐volatilememory.

Note2:SettheSwitchwithrespecttoprobeconnectedtotheinstrumentbeforeputinto
service.
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12
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ii.Testingloopoutputzero(4mA)andspan(20mA)

TheMS2901EProbeSelectionSwitches(page9)offerthreetestsettingsthatallowtheunittobe
placedintovariousdiagnosticmodesasfollows:

1) 4mAOutput–Forcesaconstant4mAoutputonthecurrentloop.
2) 20mAOutput–Forcesaconstant20mAoutputonthecurrentloop.
3) 4‐20mASweep–Causestheoutputtocontinuallycyclefrom4mAupto20mA.

Thesetestmodescanbeusefulwhentroubleshootingproblemswiththecurrentloopwiringand
DCS/SCADAsystem.

iii.TestingtheMS2901EwiththeMeterProver

AMeterProverisprovidedtoallowroutinechecksoftheMS2901E.TheMeterProversimulatesa
WireLooptypeprobeatafixedvalue.TotesttheMS2901EwiththeMeterProver:

1) Disconnectpower.
2) DisconnecttheMS2901Efromtheprobe(oriftheMS2901Eisremote‐mounted,disconnect
theprobeextensioncablefromtheprobe.)
3) ConnecttheMeterProvertotheMS2901Eprobeconnectorstem(ortotheprobeextension
cableiftheMS2901Eisremote‐mounted.)
4) LoosentheMS2901EEnclosureLockScrew.
5) UnthreadandremovetheMS2901Ecover.
6) ChangetheProbeSelectionSwitchestotheWireLoopposition(seepage9.)
7) Reconnectpowerandallowtheinstrumenttomeasureforseveralminutestostabilize.
8) Afterseveralminutesobservethetransmitteroutput.Theoutputshouldcloselymatchthe
valueprintedontheMeterProverlabel.

IfthetransmitteroutputmatchestheMeterProvervalue,youmayreturntheProbeSelection
SwitchestotheirprevioussettingandreconnecttheMS2901Etotheprobe.Ifthetransmitteroutput
showsasignificantdifferencecomparedtotheMeterProvervalue,furthertroubleshootingmaybe
required.Refertopage14fortroubleshootingorcontactthefactoryforfurtherassistance.

BesuretoreinstalltheenclosurecoverandtightentheLockScrewwhenputtingtheMS2901Eback
intoservice.
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13

c.InterpretingData

i.MetalLoss
TheMS2901EmeasurestheMetalLossofanERprobeandconvertsthatvaluetoalinearized4‐20mA
currentloopoutput.The4‐20mAoutputisdirectlyproportionaltothecumulativeMetalLossofthe
ERprobeatanygiventime.Theoverallspanofthe4‐20mAoutputisproportionaltothelifeofthe
probeinuse,soforDCS/SCADAprogrammingthe4‐20mAsignalcanbescaledasfollows:

4mA=0mils(0%MetalLoss)
20mA=ProbeLifeinmils(100%MetalLoss)

TheProbeLifecanbefoundinTable1andisalsolistedontheMetalSamplesprobetag(asthe
“Multiplier”.)



Figure6.MetalSamplesProbeTag
Figure7illustratestherelationshipbetweenLoopCurrentandMetalLoss.Inthisexampleaprobe
witha10‐millifeisassumed.However,theXaxiscouldbechangedtorepresentanyProbeLife.
Figure7.OutputRelationship
Asseenhere,thetransmitteroutputbeginsat4mAforanewprobe(zeroMetalLoss)andincreasesas
theprobeelementcorrodes,eventuallyreachingamaximumof20mAwhentheprobesensing
elementhasbeencompletelyconsumedbycorrosion(inthiscase,10milsofMetalLoss.)Atthistime
theprobehasreacheditsend‐of‐lifeandmustbereplaced.
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14

ii.CalculatingCorrosionRate

Asexplainedpreviously,ERprobesandinstrumentsreportMetalLoss.However,thevaluethatisof
ultimateinterestisCorrosionRate.TheCorrosionRateisessentiallyMetalLossovertime,sothe
CorrosionRatecanbecalculatedusingthefollowingformula:
Corrosion Rate󰇛mpy󰇜∆Loop Current󰇛mA󰇜
16 365 ∆Time󰇛days󰇜Probe Life󰇛mils󰇜

where:
  LoopCurrent(mA)isthedifferencebetweentworeadings

 Time(days)isthetimedifferencebetweenthosetworeadings
Itisacommonpracticetoprogramthisformulaintothecontrol(DCS/SCADA)systemandhaveit
calculatedCorrosionRateonacontinualbasisfromtheMetalLossdata.Thechallengeindoingthisis
selectinganappropriatetimeinterval.Usinganintervalthatistooshortmaygiveerraticresults,
whileselectinganintervalthatistoolongmaygiveresultsthatareinsensitivetosystemupsets.The
idealtimeperioddependsonmanyfactorsandwillvaryfromsystemtosystem.Itmaytakesome
trialanderrortosettleonthebesttimeperiodforyourinstallation.

Insomecases,itmaybenecessarytoreviewtherawMetalLossdataandmanuallyapplythe
CorrosionRateformulatoperiodsofinterest.Forexample,lookatthegraphbelowandseehow
muchthecalculatedCorrosionRatecanvarydependingonthetimeperiodused.

Figure8.CorrosionRatescalculatedfromMetalLossdata
Whileeachoftheresultsisvalidfortheselectedtimeperiod,theoneofmostinterestisthevalueof
11.81mpywhichrepresentssometypeofsystemupset.WhentheCorrosionRateiscalculated
automaticallyonapre‐selectedtimeperiod,thereisnoguaranteethattheselectedtimeperiodwill
alwayscoincidewithsystemupsetssuchasthis.Thatiswhymanualreviewandinterpretationof
MetalLossdataisalsohelpful.
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

15

AlarmlimitsandCurrentRanges

Aguaranteedlinearover‐rangeisprovided.Devicemalfunctioncanbeindicatedbyup‐scalecurrent.
Currentvaluesareshowninthetablebelow.

DirectionValues(percentof
range)
Values(mAorV)
Linearover‐rangeDown‐0.6%0.1%3.89to3.92mA
Up+105.0%1.0%20.64to20.96mA
Devicemalfunction
indication
Down:lessthan‐1.8%3.70mA
Up:greaterthan+115.0%22.50mA
Maximumcurrent+115.0%22.50mA
Multi‐Dropcurrentdraw4.0mA


16

d.Commissioning

OncetheMS2901Etransmitterhasbeeninstalled,tested,andproperlyconfiguredfortheprobe
inuse,itcanthenbeclosedandputintoservice.First,performonelastvisualinspectionto
ensurethatallelectricalconnectionsaresecureandthattheenclosureo‐ringisinplaceandisin
goodcondition.Thenthreadtheenclosurelidontothebasefully.Oncethelidhasbeen
threadedintoplace,tightentheLockScrewtopreventunauthorizedtampering.









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










Figure10.Enclosure
Lock
Screw 


CAUTION: TheLockScrewontheinstrumentbasemustbetightenedsecurelytoprevent
unauthorizedpersonnelfromopeningtheMS2901Etransmitter,andensurethattheflameproof
safetyisnotviolated.Onlyqualifiedpersonnelshouldbeallowedtoinstall,operate,and
maintenancetheMS2901Etransmitter.

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