Metal Samples CORR VELOX MS2801E User manual

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Ultra Resolution ER RS-485 Transmitter
(Model MS2801E)
Operator’s Manual
Metal Samples
ADivisionof Alabama SpecialtyProducts, 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
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MS2801Etransmitter..........................................................................................4
B.Installation.................................................................................................................................4
1.PhysicalMountingandProbeConnection...................................................................4
a.Direct‐ProbeMounting......................................................................................4
b.RemoteMounting.............................................................................................5
2.PowerandDataConnections......................................................................................6
a.MakingConnections........................................................................................6
b.Grounding.........................................................................................................7
c.SafeAreaInstallation........................................................................................7
d.HazardousAreaInstallation..............................................................................7
3.SetupandOperation......................................................................................................9
a.ProbeSettings.................................................................................................9
b.RS‐485CommunicationSettings..................................................................10
i.BaudRateandDefaultCommunicationParameters.............................11
ii.DeviceAddress......................................................................................11
iii.CommunicationProtocols.....................................................................11
iv.TerminationResistor.............................................................................11
v.DataRegisters.......................................................................................12
c.CalibrationandTesting................................................................................12
i.Calibration..............................................................................................12
ii.Testingoutputzeroandspan
.................................................................12
iii.TestingtheMS2801EtransmitterwiththeMeterProver......................13
d.InterpretingData...........................................................................................14
i.MetalLoss................................................................................................14
ii.CalculatingCorrosionRate......................................................................15
e.Commissioning..............................................................................................16
C.Maintenance............................................................................................................................16
D.Troubleshooting.......................................................................................................................17
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III.ServiceandWarrantyInformation.......................................................................................................18
A.Warranty..................................................................................................................................18
B.ObtainingServiceandReturningtheInstrumentforRepair...................................................18
C.InstrumentRepairForm...........................................................................................................19
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AppendixA–RevisionHistory....................................................................................................................20
AppendixB–HazardousAreaCertificationDetails...................................................................................21
AppendixA‐Drawings..............................................................................................................................22
ControlDrawing(HazardousAreaWiringDiagram)....................................................................22
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1
I. Introduction
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A.GeneralDescription
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ThemodelMS2801ECorrVelox transmitterisanultra‐highresolutioninstrumentdesignedto
measureandtransmitcorrosion(metalloss)datafromanElectricalResistance(ER)probetoaplant
controlsystemorotherrecordingdevice.TheCorrVelox transmitterutilizesRS‐485
communicationwhichallowsmultipleunitstobedaisy‐chained,simplifyinginstallationandreducing
associatedcosts.TheuseoftheRS‐485protocolalsoallowsthetransmittertobeplacedgreat
distancesfromthecontrolsystemorrecorderwhilemaintaininggoodnoiserejection.Practical
distancescanbeupto4000feet.Additionally,theCorrVelox transmitteroffersuser‐selectable
RTUorASCIIcommunicationprotocolsmakingithighlyversatile.
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TheCorrVelox transmitteriscompatiblewithalltypesofMetalSamplesERprobes,aswellasany
standardERprobefromothermanufacturers.Unlikecompetitors’products,theCorrVelox
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.)
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TheCorrVelox transmitterisavailableasdirect‐mountorremote‐mount.Thedirect‐mountversion
ismounteddirectlytotheERprobe.Thisoptionoffersthesimplestinstallationandminimizesnoise
problems.Theremote‐mountoptionallowstheCorrVelox transmitter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pages5and6formountingdiagramsandspecifications.)
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B.PrinciplesofOperation
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TheCorrVelox transmitter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.
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TheCorrVelox transmitter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.
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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

ElementType Compatibility Thickness ProbeLife
(Span)
TubularLoop Compatible 42
84
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
52.5
10 5
20 10
40 20
Table1.StandardERProbeElements
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TheCorrVelox transmittermeasuresanERprobeutilizingahigh‐resolution,20‐bitmeasurement.
Thisallowstheunittodetectmuchsmalleramountsofmetalloss,thusrespondingfastertocorrosion
eventsandupsets. At20‐bitresolutiontheCorrVelox transmittercanmeasuremetallossamounts
assmallas0.0001%oftheprobelife. Forhighlysensitiveprobessuchasthe5‐millargeflushshown
above,thatresultsinadetectionlimitoflessthanoneangstrom.

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MetallossreadingstakenbytheCorrVelox transmitterareoutputasadigitalRS‐485signalwhich
canbefedintoaplantcontrolsystemorotherrecordingdevices.TheMetalLossisrepresented
bya 
20‐bitdigitalvaluebetween0and1,048,575,where:


0=0mils(0%MetalLoss)
1,048,575=ProbeLife*inmils(or100%MetalLoss)


*TheProbeLife(orSpan)oftheprobebeingused(seetable1above.)


TheMetalLossdatacanbeusedtocalculatethecorrosionratebetweenanyperiodsofinterest.
Thisiscoveredinmoredetailonpages13and14. MoreinformationonERprobes,theirtheory,
selection,andusecanbefoundonourwebsiteathttp://www.alspi.com/erintro.htm.

3
C.TechnicalSpecifications
ModelMS2801E CorrVelox HighResolutionERRS‐485ModbusTransmitter
PhysicalData
InstrumentWeig ht: 3.70lb.(1.68Kg)Total
Weightw/Accessories:5.76lb.(2.61Kg)
InstrumentDimensions:8.0"Hx4.0"Wx3.45”D
4.82”W
(12.24cm)
8.0”H
(20.32cmHx12.24cmWx8.76”D)
OperatingTemperature: ‐40°to158°F(‐40°to70°C)
StorageTemperature: ‐40°to176°F(‐40°to80°C)
EnclosureMaterial:CastAluminum(Copper‐Free)
MountingSpecifications:Directprobemountor
Remotemount
(Uptoa2.5”(6.35cm)Dia.pole)
(20.32cm)
3.45”D
(8.76cm)
PerformanceData
MeasurementType:ERmeasurement
Range:0‐100%ofprobelife
Resolution:0.0001%ofProbeLife(20‐bit)
CycleTime:75Seconds
Figure1.OverallDimensions
ElectricalData
PowerRequirements:10to30VDC
MaximumProbeCableDistance:30ft(9.1m)
OutputSpecifications:RS‐485Modbus,RTUorASCIIProtocol(SwitchSelectable)
2400/4800/9600/19.2KSelectableBaud
32MaximumUnits(Addresses1to32)
HazardousLocationCertifications–Transmitter
EuropeandWorldwide
(ATEXandIECEx)Exdb[iaGa]IICT6….T4Gb

Extb[iaGa]IIICT75°CGb
‐40°C≤Ta≤+70°C
ATEXCertificateNo:ITS18ATEX203437X
IECExCertificateNo:IECExETL18.0020X
X‐seeSpecialConditions(page7)
HazardousLocationCertifications–Enclosure
CaseSpecifications:ExplosionProof(FM,CSA,CENELEC,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MS2801ECorrVelox Transmitter

ChecktheCorrVelox Transmitterforanyshippingdamagewhenitisfirstreceived.Whentheunitis
unpacked,verifythatthefollowingitemsareincluded:

Transmitter
MeterProver
User’sManual
ProbeCable(forremote‐mountonly)
MountingHardware(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

CAUTION:Usingthisproductinanywayotherthanthatspecifiedwithinthismanualmayimpairthe
intrinsicsafetyprotection.


InstallationoftheCorrVelox 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CorrVelox transmitteritisimportanttoconsiderthe
surroundingenvironment.Toensureproperoperation:

Donotmountthetransmitterinalocationthatexceedsitsoperatingtemperature.
Avoidmountingthetransmitter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CorrVelox transmitter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CorrVelox transmitter,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.
TomounttheCorrVelox transmitter:

5
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.
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AlignKey
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Insert 
Connector 
Tighten
CouplingNut
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123
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Figure2.DirectMountInstallation
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b.RemoteMounting
Whenitisnotpracticaltodirect‐probemounttheCorrVelox 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.
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Figure3.RemoteMountInstallation

6
2. Power and Data Connections
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a.MakingConnections
TheRS‐485fieldwiringentersthetransmitterthroughthe1/2"femaleNPTconduitportshownin
Figure4below.
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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.
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ProbeConnectorStem
orProbeCable
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1/2”FNPTConduitPortfor
FieldWiringEntry
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Figure4.RS‐485 Connector 
ElectricalconnectionsaremadetothemainPCBviatheterminalblocksJ2andJ9asshowninFigure6.
NOTE:DonotconnectcableshieldingtotheTransmitter.Theshieldmustremainfloatingatthe
Transmitter.
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TheRS‐485protocolallowsupto32transmitterstobedaisy‐chainedwhichsimplifiesinstallationand
reducescosts.Figure5showsanexampleofatypicalarrangement.Fullwiringdetailsareshownon
pages21and22.
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CAUTION:Besuretoobservetheappropriategasgroupratinglistedonpage3forstand‐aloneor
multi‐dropoperation.
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Figure5.Typicaldaisy‐chainarrangement,where‘n’isthenumberofthelast transmitter. 

7
ThemaximumpermissiblelengthofthefieldwiringbetweentheCorrVelox transmitterandthe
controlsystemisdeterminedbythecontrolsystemsupplyvoltage,theelectricalresistanceof
the
cable
andtheloadofthecontrolsysteminput.IftheTransmitteristobeinstalledinasafearea,refer
tosectionc.SafeAreaInstallationfordetails.IftheTransmitteristobeinstalledinahazardousarea,
refertosectiond.HazardousAreaInstallation.
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b.Grounding
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TheCorrVelox transmitter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.
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c.SafeAreaInstallation
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TheCorrVelox transmitterisapprovedforuseinhazardousareas,butcanbeusedinnon‐
hazardousareasaswell.Forbasicsafeareawiring
information refertothecircuitdiagramshownon
page21.
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CAUTION:Whenusedinnon‐hazardousareas,equipmentmustbesuppliedwithapre‐approvedpower
supplyunitorapprovedequipmentwhichmeetstheentityparametersshownbelow.
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Thepre‐approvedequipmentmustbecertifiedtotheelectricalsafetystandardsforequipmentin
ordinarylocations(forexample,EN/IEC/CSAUL61010‐1orEN/IEC/CSAUL60950‐1).Failuretomeet
theserequirementswillvoidtheintrinsicsafetycertificationoftheequipmentandprohibititsfuture
useinhazardousareas.
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d.HazardousAreaInstallation
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CAUTION:Thissectionprovidesgeneralguidelinesforhazardousareawiring.However,regardlessof
anythingstatedhere,theCorrVelox transmittermustbeinstalledinfullcompliancewiththecontrol
drawinglocatedonpage20andallofthelocalarearequirements.
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CAUTION:WhenusedinHazardousareas,equipmentmustbesuppliedwithapre‐approvedpower
supplyunitorapprovedequipmentviaacertifiedintrinsicallysafebarrieroragalvanicallyisolated
barrier)withthefollowingentityparameters.
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Input supply terminal (J1)
Um = 30.0V DC
Um = 6.0V RS485
Probe Connector (J3)
Uo =5.115 Vdc
Io = 0.344 A
Po = 0.44 W
Co = 0.5 uF
Lo = 35 uH

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SpecialConditions
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1.AllCableGlands,blankingelementsandthreadadaptersusedwiththeequipmentshallbesuitable
certifiedExdbparts,providingadegreeofprotectionofIP66andbesuitableforuseinambient
temperaturerangeof‐40DegC.to70Deg.C.
2.NomorethanoneHazardousareareducershallbeusedonanyentry.
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CAUTION:Forhazardousareainstallations,themaximuminductanceandcapacitanceofthefieldwiring
betweentheconnectedequipmentandthetransmittercannotexceedtheentityparameters.
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CAUTION:Non‐MetallicHazardousarealabelontheinstrumentmayposeapotentialelectrostatichazard.
Followingprecautionsmayhelptoreduceriskduringmaintenance/handlingtheequipment.Thestaticcharge
canbedissipatedbyfollowingsimplesteps
a. Usedampenedclothtocleanthelabelsurfacebeforehandlingit.
b. Bodycanbegroundedbyusingground/anti‐staticwristbandsorbyothermeansbeforehandling.
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9
3. Setup and Operation
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a.ProbeSettings
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Theprobeselectionswitchesarelocatedonthetopleftcornerofthemainboardasillustratedin
Figure6below.TheseswitchesareusedtosettheERprobetype.Theyalsoallowtheinstrumentto
beplacedintoseveraltestmodeswhichoutputfixedvalues,allowingverificationoftheoutputsignal.
Table2givestheswitchsettingsforeachprobetypeandthevarioustestmodes.
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Switch1‐Probe
SelectionSwitch
(SeeTable2below)
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PowerandData
Connector
(J2)
ProbeCableConnector
(J1)
Switch2‐RS‐485
ConfigurationSwitches
(SeeTable3below)
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Figure6.ConnectorandSwitchDetails
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Switch1
Setting
Position
1 2 3 4
Operating
Positions
Wire Loop Off (↓)On (↑) On (↑) Off (↓)
Tube Loop/Flush On (↑) Off (↓)On (↑) Off (↓)
Cylindrical
*
Off (↓)Off (↓)On (↑) Off (↓)
MC Probes Off (↓) Off (↓) Off (↓)Off (↓)
Test
Positions
Zero Output (0) On (↑) On (↑) Off (↓)Off (↓)
Maximum Output
(1,048,575) Off (↓)On (↑) Off (↓)Off (↓)
Full Scale Sweep On (↑) Off (↓)Off (↓)Off (↓)
Maintenance
Position Service Registers * * * On (↑)
Table2.ProbeSwitch Settings 
*Cylindricalprobesettingisillust rate d.

10
b.RS‐485CommunicationSettings
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TheRS‐485configurationswitchesarelocatedonthetoprightcornerofthemainboardasillustrated
inFigure6.Theseareusedtosettheinstrumentaddress,baudrate,communicationprotocol,andto
enabletheterminationresistor.Table3givestheswitchsettingsforeachoftheseparameters,and
theyareexplainedinmoredetailbelow.
Switch2(12Positions)
Device
Address
Position
34567
1Off (↓)Off (↓)Off (↓)Off (↓)Off (↓)
2On (↑)Off (↓)Off (↓)Off (↓)Off (↓)
3Off (↓)On (↑)Off (↓)Off (↓)Off (↓)
4On (↑)On (↑)Off (↓)Off (↓)Off (↓)
5Off (↓)Off (↓)On (↑)Off (↓)Off (↓)
BaudRatePosition6On (↑)Off (↓)On (↑)Off (↓)Off (↓)
127Off (↓)On (↑)On (↑)Off (↓)Off (↓)
2400Off (↓)Off (↓)8On (↑)On (↑)On (↑)Off (↓)Off (↓)
4800Off (↓)On (↑)9Off (↓)Off (↓)Off (↓)On (↑)Off (↓)
9600On (↑)Off (↓)10On (↑)Off (↓)Off (↓)On (↑)Off (↓)
19200On (↑)On (↑)11Off (↓)On (↑)Off (↓)On (↑)Off (↓)
12On (↑)On (↑)Off (↓)On (↑)Off (↓)
Communication
Protocol
Position13Off (↓)Off (↓)On (↑)On (↑)Off (↓)
8914On (↑)Off (↓)On (↑)On (↑)Off (↓)
ModbusASCIIOn (↑)Off (↓)15Off (↓)On (↑)On (↑)On (↑)Off (↓)
ModbusRTUOff (↓)Off (↓)16On (↑)On (↑)On (↑)On (↑)Off (↓)
SerialASCIIOn / Off On (↑)17Off (↓)Off (↓)Off (↓)Off (↓)On (↑)
18On (↑)Off (↓)Off (↓)Off (↓)On (↑)
TerminationPosition19Off (↓)On (↑)Off (↓)Off (↓)On (↑)
Resistor1220On (↑)On (↑)Off (↓)Off (↓)On (↑)
ActiveOn (↑)21Off (↓)Off (↓)On (↑)Off (↓)On (↑)
InactiveOff (↓)22On (↑)Off (↓)On (↑)Off (↓)On (↑)
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23Off (↓)On (↑)On (↑)Off (↓)On (↑)
24On (↑)On (↑)On (↑)Off (↓)On (↑)
SparePosition10&1125Off (↓)Off (↓)Off (↓)On (↑)On (↑)
26On (↑)Off (↓)Off (↓)On (↑)On (↑)
27Off (↓)On (↑)Off (↓)On (↑)On (↑)
28On (↑)On (↑)Off (↓)On (↑)On (↑)
29Off (↓)Off (↓)On (↑)On (↑)On (↑)
30On (↑)Off (↓)On (↑)On (↑)On (↑)
31Off (↓)On (↑)On (↑)On (↑)On (↑)
32On (↑)On (↑)On (↑)On (↑)On (↑)
Table3.RS‐485ConfigurationSwitchSettings

11
i.BaudRateandDefaultCommunicationParameters
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ThedefaultcommunicationparametersfortheCorrVelox transmitterareprovidedinTable
4below. 
Ifnecessary,thebaudratecanbechangedusingPositions1and2ofSwitch2,asillustratedinTable3.
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Modbus
RTU
Modbus
ASCII
Serial
ASCII
ParameterValueValueValue
BaudRate19200192002400
DataBits878
ParityEvenEvenEven
StopBits111
ResponseTimeOut3000mS3000mS3000mS
PollingInterval1min1min1min
RTSToggleActiveActiveActive
RTSDisableDelay1mS1mS1mS
Table4.DefaultCommunicationParameters
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ii.DeviceAddress
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Upto32CorrVelox transmittersmaybeconnectedinamulti‐dropnetwork(“daisy‐chained”) usinga 
singlecablerun.However,eachtransmittermustbesettoauniquedeviceaddresstoavoidconflicts.
ThisisdoneusingPositions3through7ofSwitch2,asillustratedinTable3.

CAUTION:Besuretoobservetheappropriategasgroupratinglistedonpage3forstand‐aloneor
multi‐dropoperation.


iii.CommunicationProtocols

TheCorrVelox transmitteroffersuser‐selectableRTUorASCIIcommunicationprotocols,givingthe
unitabroaderrangeofcompatibility.ThecommunicationprotocolissetusingPosition8ofSwitch2,as
illustratedinTable3.

iv.TerminationResistor

Toensureproperoperation,theRS‐485networkmustbeterminatedproperlywithatermination
resistor.Tofacilitatethis,eachCorrVelox transmitterhasabuilt‐in120terminationresistorthat
canbeswitchedonoroffusingPosition10ofSwitch2.Onceallunitshavebeeninstalled,besureto
enabletheterminationresistorofthelastunitinthenetwork.Theterminationresistorsofallother
transmittersshouldbeturnedoff.



12
v.DataRegisters

Table5liststhedataregistersoftheCorrVelox transmitter.DataRegister40024and40025
transmittedfromthetransmitteristhedirectprobereadingvalue.

NoRegister
Address
Description
140024DACValue(Low)
240025DACValue(Hi)

Toaccessallotherregistersformaintenancepurpose,theSwitch1,Position#4(Maintenance)should
beturnedon.

NoRegister
Address
Description
140001DeviceStatus
240002DeviceAddress
340003BaudRate
440024DACValue(Low)
540025DACValue(Hi)
640026ProbeSwitchSetting
Table5.ModbusDataRegisters




c.CalibrationandTesting
i.Calibration
TheCorrVelox transmitterisfullycalibratedwhenshippedfromthefactory.Thecalibration
settingsarefixedtoavoidaccidentalchangewhichcouldresultinerroneousdata.Nofieldcalibration
isrequired.However,itisimportanttotesttheunituponinstallation,andduringperiodic
maintenanceinspections,toensuretheunitisoperatingproperly.

ii.Testingoutputzeroandspan

TheCorrVelox transmitterProbeSelectionSwitches(page9)offerthreetestsettingsthatallowthe
unittobeplacedintovariousdiagnosticmodesasfollows:

1) ZeroOutput–Forcesadigitaloutputof0.
2) MaximumOutput–Forcesadigitaloutputof1,048,575.
3) FullScaleSweep–Causestheoutputtocontinuallycyclefrom0upto1,048,575.

Thesetestmodescanbeusefulwhentroubleshootingcommunicationproblemsbetweenthe
transmitterandtheDCS/PLCsystem.



13
iii.TestingtheCorrVelox transmitterwiththeMeterProver

AMeterProverisprovidedtoallowroutinechecksoftheCorrVelox transmitter.TheMeterProver
simulatesaWireLooptypeprobeatafixedvalue.TotesttheunitwiththeMeterProver:

1) Disconnectpower.
2) DisconnecttheCorrVelox transmitterfromtheprobe(oriftheunitisremote‐mounted,
disconnecttheprobeextensioncablefromtheprobe.)
3) ConnecttheMeterProvertotheprobeconnectorstem(ortotheprobeextensioncableifthe
CorrVelox transmitteris
remote‐mounted.) 
4) LoosentheEnclosureLockScrew.
5) Unthreadandremovethetransmitter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CorrVelox transmitter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16fortroubleshootingorcontactthefactoryfor
furtherassistance.

BesuretoreinstalltheenclosurecoverandtightentheLockScrewwhenputtingtheCorrVelox
transmitterbackintoservice.




14
RS‐485ModbusOutput
d.InterpretingData
i.MetalLoss
TheCorrVelox transmittermeasurestheMetalLossofanERprobeandconvertsthatvaluetoa
digital20‐bitRS‐485Modbusoutput.ThisoutputisdirectlyproportionaltothecumulativeMetalLoss
oftheERprobeatanygiventime.Theoverallspanoftheoutputisproportionaltothelifeof
the
probe
inuse,soforDCS/PLCprogrammingtheRS‐485Modbusoutputcanbescaledasfollows:

0=0mils(0%MetalLoss)
1,048,575=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7.MetalSamplesProbe Tag 

Figure8illustratestherelationshipbetweenthedigitaloutput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.


1048575


786431


524288


262144


0 
0.02.55.07.510.0
New 
Probe MetalLoss(mils)
Probe 
Consumed 



Figure8.Output Relationship 

Asseenhere,thetransmitteroutputbeginsat0foranewprobe(zeroMetalLoss)andincreasesasthe
probeelementcorrodes,eventuallyreachingamaximumof1,048,575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.

15
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)=
∆MetalLoss(mils)
∆Time(days)

x 365


where:

∆MetalLoss(mils)isthedifferencebetweentwoMetalLossreadings
Time(days)isthetimedifferencebetweenthosetworeadings


Itisacommonpracticetoprogramthisformulaintothecontrol(DCS/PLC)systemandhaveit
calculate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9.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.

16
e.Commissioning

OncetheCorrVelox 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.





















Figure10.EnclosureLock Screw 


CAUTION: TheLockScrewontheinstrumentbasemustbetightenedsecurelytopreventunauthorized
personnelfromopeningtheCorrVelox transmitter,andensurethattheintrinsicsafetyisnotviolated.
Onlyqualifiedpersonnelshouldbeallowedtoinstall,operate,andmaintenancetheCorrVelox
transmitter.



C.Maintenance
Onceinstalled,theCorrVelox transmitterrequireslittlemaintenance. However,itisimportanttoverify
the followingitemsperiodicallytoensurecontinuedsafe operation.

CAUTION: BeforeperforminganytestsormaintenanceontheCorrVelox transmitter,ensurethatall
hazardousarearequirementsaremet.


InspectionItem Frequency
Inspecttheenclosureo‐ringforanysigns of damage. Replace as necessary. Annually
Inspecttheprobeconnectoro‐ringforany signs of damage. Replace as necessary. Annually
Inspectallelectricalconnectionsforsigns of corrosion, mechanical damage, or foreign
matterthatcouldcauseimproperoperationorcauseanelectricalshort.Cleanasnecessary.
Annually
Ensurethatthelockingscrewisinplaceand issecure. Annually
Inspecttheenclosureforanysignsofcorrosion or paint damage. Annually
Checkforanysignsofmoistureingresswithin the enclosure. Annually
ContactMetalSamplesforreplacementpartsorifinstrumentrepairisnecessary.