Understanding Ultrasonic Level Measurement - Gilson Eng

Understanding

Ultrasonic Level

Measurement

third edition SIEMENS

Gilson Engineering | 1-800-866-4499 | www.gilsoneng.com

AcknowledgementsAsyoucanimagine,aprojectlikethisinvolvestheeffortsandcontributionsofmanypeople.Tobeginwith,theauthorswanttothankthegenerationsofengineers,designers,applicationspecialists,salespeople,supportstaff,andmanagementwhohavedevelopedthetechnologyandtheproductsovertheyears.Allofusalsooweahugedebtofgratitudetoourcustomerswhohaveallowedustogrowandtoshareintheirsuccessesbyparticipatinginourvision.Alltogether,theyhavecreatedtheSITRANSLUT400,therevolutionaryultrasoniccontrollerwithonemillimeteraccuracythemarketshavebeenwaitingfor.

Theauthorsalsowanttothankallofthewritersandphotographerswhohavecontributedmaterialusedinthisbook,bothinspecificcontentandforgeneralbackgroundinformation.Theyaretoonumeroustomention,buttheirenthusiasmforthetechnologyandtheireffortsaremuchvalued.TheartisticcontributionsofPeterFroggattarealsoappreciated.Overtheyears,hisdrawingsandphotoshavehelpeddefinetheproductline,andhisworkgracesmanyofthepagesinthishumbletome.Thosewhotookthetimetoeditandprovidecommentsandotherinputalsohaveourgratitude.

Specifically,wewanttothanktheeditingandorganizationalskillsofJamieChepeka.Herdedicationtotheprojectwasunwavering,eveninthefaceofloomingdeadlinesandcreativeangst.Withouthermanagementguidance,wewouldstillbestaringatourscreens.

Lastly,theauthorsapologizeinadvanceforanyandallmistakes,inaccuracies,andomissions.Wetakefullresponsibilityandassureyouthatwewilldobetternexttime.

Contents

ChapterOneHistoryofultrasonicsUltrasonicsandlevelmeasurementProductdevelopmentmapUltrasonictheorySoundUsingsoundFrequencyandwavelengthMeasurementprincipleThemediumandthemessageSoundintensitySoundvelocityandtemperatureSoundvelocityandgasSoundvelocityandpressureSoundvelocityandvacuumSoundvelocityandattenuationSoundreflectionSounddiffractionSoundpressurelevel(SPL)Soundintensitychanges

Summary

ChapterTwoUltrasonicinstrumentationThetransducerTransducerenvironmentsTransduceraccuracyTransducerresolutionandaccuracyImpedancematchingAxisoftransmissionBeamwidthBeamspreadingRingdownThecontrollersDigitalfilteringAveragingechoesEchoextractionalgorithms

Summary

ChapterThreeThesoundandtheslurryTopicsTransducersandultrasonicsystemsSinglesystemsCompoundsystems

TransducersTemperatureandtransducermaterialTemperaturesensors

SoundanddifferentialamplifiersSingle-endedreceiverDifferentialreceiverApplicationtemperatureHousingmaterialRangeandpowerConditionsTransducerselectionBlankingdistanceandheightplacementTemperatureInstallationTransducerdesign:theheartofthematter

Summary

ChapterFourEchoprocessingTopicsEchoprocessing-intelligenceUnderstandingechoprocessingShotsandprofilesFindingthetrueechoEchoqualityFigureofmeritEchoparameterfinetuningEchoprofilesProfilecomponentsEchoprofileRingdownTVTcurve(TimeVaryingThreshold)EchomarkerEcholockwindowEchoprocessingparametersEchoconfidenceTheechoEchostrength

NoiseNoiseinterferenceDeterminingthenoisesource

Non-transducernoisesourcesCommonwiringproblemsReducingelectricalnoiseAcousticnoiseReducingacousticnoise

Summary

ChapterFiveInstallationTopicsSelecttherighttransducerLocationObstructionsClosedvesselsTanksTankaccessOpenvesselsOpenchannelmeters:weirsandflumesFlumesTransducerlocationLiftstationsPositioncontrolHazardousapprovalsApprovalsControllerinstallation

Summary

ChapterSixApplicationsApplicationsTopicsCementMiningChemicalstorageAggregateBlendingsilosandstoragebunkers

EnvironmentalCollectionsystem:liftstation/pumpstation/wetwellWastewatertreatmentplantEnvironmentalapplicationsFoodindustryChemicalindustry

Otherindustries

ChapterSevenBestinclass–theultrasonicproductlineSITRANSLUT400Keybenefits

SITRANSProbeLUKeybenefits

TheProbeKeybenefits

MultiRanger100/200Keybenefits

SITRANSLU10Keybenefits

HydroRanger200Keybenefits

EchomaxTransducersXRS-5Keybenefits

XPS/XCTSeriesKeybenefits

XLTSeriesKeybenefits

ST-HKeybenefits

Conclusion

GlossaryWorksCited

ChapterOne

HistoryofultrasonicsHowsweetthatjoyoussound,wheneverwemeet.1

SiemensMilltronicsProcessInstrumentshasalongandsuccessfulhistoryspecializinginthemanufactureofequipmentforindustrialprocessmeasurement.BasedinPeterborough,Canada,SiemensMilltronics(PI2)isnowakeymemberoftheSensorsandCommunicationdivisionwithintheSiemensIndustrydivision,supplyinginstrumentationacrosstheglobe.

Foundedin1954byStuartDaniel,aformeremployeeofCanadianGeneralElectric,thecompanybeganasMilltronicsandengineeredelectronicballmillgrindingcontrolsforthecementandminingindustry.Fromthis,thecompanyexpandedanddiversifieditsproductlinetodevelopawiderangeofprocessmeasurementdevices.Ithasbecomealeaderinlevelmeasurementtechnology.TheSiemensMilltronicsrangeofinstrumentationnowincludesultrasonic,radar,andcapacitancetechnologies,butthefoundationofitsinnovationandsuccessfuldesignandtechnicalexpertiseliesinitsultrasonicecho-rangingtechnology.

SiemensMilltronicsultrasonicecho-rangingtechnologycompriseshighlysophisticatedinstrumentationapplyingdigitalcircuitrytoultrasonicecho-ranging.Thisinnovationhasproducedarangeoftechnologicallyadvancedproductscapableofmonitoringliquidandsolidslevelsfromafewcentimeterstoover60meters(200ft).Todate,over1,000,000pointsoflevelonadiverserangeofmaterial,includingsolids,liquids,slurries,andresins,aremonitoredacrosstheglobebySiemensMilltronics,manyinhostileandhazardousenvironments.

TheSiemensMilltronicsultrasonicproductlineisconstantlyimprovingastechnologicaladvancesareimplemented,newproductsaredeveloped,andnewapplicationsaretackledandwonover.Complementedbyateamofhighlyskilledapplicationsengineers,servicepersonnel,andadedicatedSiemenssalesforce,SiemensMilltronicscontinuestoprovide

reliableandinnovativelevelsolutionstoindustryacrosstheglobe.

UltrasonicsandlevelmeasurementThemeasurementoflevelhasbeenintegraltohumandevelopmentsincepre-industrialtimes.

“Egypt,”Herodotusremarkedmorethan2000yearsago,referringtothevastirrigationprojectthatsustainsthatcountry’sagriculture,“isthegiftoftheriver.”EveryJune,assnowmeltsfromtheTanzanianHighlandsandspringrainfromtheCongobeginaccumulatingintheNile,itselevationbeginstorise.ItrisesgentlytoacrestinlateSeptemberorearlyOctober,thensubsidesbylateDecember.Seedgoesintotherich,freshlydepositedsiltassoonasthefloodrecedes.

Egyptianengineersbegancapturingtheriverforirrigationprojectsabout7,000yearsago.Becausethesystemreliesonacomplicatedsystemofgatestodistributewateracrossabroad,relativelyflatarea,it’svitalthatengineersknowtheheightoftheriverinadvanceofitsarrival.Thefirstsolutionwastosimplymarktheriverbanksandconveyinformationbacktoheadquartersviarunners.Later,engineersdevelopedalargevarietyof“nilometers,”devicesusedto

measuretheriverheight.Most,however,consistedofordinarygraduatedscalesthatprojectedverticallyupwardfromtheriverbedandwerereaddirectly.

Today,theU.S.GeologicalSurveyandtheNationalOceanicandAtmosphericAdministrationusesimilardevices:graduatedpolesstuckintothewater.Techniciansreadmostofthemmanually,buttherearesomeinflood-proneareasthattransmitinformationdirectlytotheagencyviaradio.Thoughmillennia-oldsolutionsformeasuringriverlevelarestillinuse,therearethousandsoflevel-determinationproblemsinindustrythatdemandmuchmoresophisticatedsolutions.Liketheirforebears,contemporaryengineershaverespondedwithimpressiveingenuity.2

IngenuityisalsothekeytothesuccessofSiemensMilltronicsultrasonictechnologyasitmeetsthedemandsoflevelmeasurementintheprocesssystemsmarket.TheneedforprocessmeasurementdatesbacktotheIndustrialRevolutionwhenthedevelopmentofthesteamenginecreatedarequirementfortheaccuratemeasurementoftemperature,pressure,andflow.

Bytheearlytwentiethcentury,processengineersweredeterminingprocessmeasurementsusingavarietyofmechanicaldevicesincludingfloats,sightglasses,thermometers,gauges,andarmatures.Accuracywasoftenelusive,andthesedevicesweresupplementedbyhumanexperience.Processengineersoftenreliedontheirsensestocomplementthetechnology:usingsight,sound,touch,smell,andeventexture,engineerswouldexamineprocesssmoke,liquidclarity,texture,andsmelltodetermineproductquality.However,chemicalcompounds,safetyrestrictions,systemcomplexity,andawarenessnowmakethistypeoftactileverificationimpossible,requiringmeasurementtobemadebytheinstrumentalone.

Processmeasurementincorporatesavarietyofsolutions,frompressureandtemperaturetoflowandlevel.WhileSiemensSCPIoffersinstrumentationtomeasureallofthese,SiemensMilltronicsspecializesinthecalculationoflevel.

Levelmeasurementinstrumentationcurrentlyemploysavarietyofsophisticatedtechnologies,withultrasonicmeasurementasthecornerstone.Theoriginsofultrasonicmeasurementtechnologylieinearlyusebysubmarinesofsonarfordepthgaugingandmarinedetection,butitwasn’tuntil1949thattheseprincipleswereappliedtolevelmeasurement.BobRedding,ofEvershedandVignoles,developedanultrasonicinstrumentwithservocontrolthatautomaticallymeasuredoillevelandthentransferredthatinformationtoaremoteindicator.

OthertechnologieswerealsoappliedtoremotelevelmeasurementbycompanieslikeMagnetrol,whichapplieditsmagneticswitchingtechnologytothecontrolofpumpsandotherdevicesforuseinwaterlevelalarming.Thedevicetransmittedlevelchangestotheswitchmechanismwithoutanymechanicalorelectricalconnectionandeliminatedmechanicaldevicessuchasdiaphragmsandstuffingboxes.

In1963,MagnetrolintroducedModulevel©3,thefirstmagneticallycoupledpneumaticproportionallevelcontrol.Thefirstsignificantsensinginstrument,itledthewaytonewmarketsincontinuousprocesslevelcontrol.Bythe1970s,ultrasonictechnology,alreadyusedinshipandplanedetection,wasdevelopedforthemeasurementindustries.Sonarprincipleswereappliedtouseinair,usingmodifiedlowfrequencysonarequipmentwithpiezoelectriccrystalstogenerateechoranging.Thesenewsensorswereappliedtoprocesscontroltaskssuchaspointlevel,continuouslevel,concentration,andfullpipeapplications.Inthemid-1980s,analoginstrumentationwentdigitalandoffered4to20mAsignal,openingupcommunicationpossibilities,andgreatlyincreasingitsvalueascontrolinstrumentation.

Milltronicsenteredthemarketintheseearlydaysofultrasonicdevelopment.In1973,afterbeingthemainRaytheon®4distributorinCanadaandtheUSA,MilltronicsacquiredtheRaytheonUltrasonicRangingbusinesssegmentandtheAiRangerIIproduct.Overthenext30years,Milltronics®5hasbecomethemarketleaderandthemosttrustednameinultrasonicslevelmeasurement.AftertheSiemensacquisitionin

2000,theMilltronicsbrandhascombinedwiththeTotallyIntegratedAutomationvisionofSiemenstoofferultrasoniclevelmeasurementequipmentasanintegralcomponentofcompletesystemdesign.

Productdevelopmentmap

Ultrasonictheory

Ultrasonicmeasuringtechnologyoperatesonthesimpleprincipleofmeasuringthetimeittakessoundtotraveladistance.Whiletheideaissimple,theprocessofcreating,controlling,andmeasuringthesoundtravelisnot.

SoundSoundistheinterpretationofelectricalsignals.Thesesignalsarederivedfromacousticpressurewavesthatactivateatransducersimilartothehumanear.Thisorganictransducerinterpretstheelectricalsignalschanneledintotheearcanal.

Thesoundsignalsarecausedbythemechanicalvibrationoftheobject.Thevibrationistransferredtothegasmodulesinthesurroundingmediumwithinwhichitiscontained.Thetransferoccursasthevibrationsalternatelycompressanddecompressthemoleculesnexttotheobject,spreadingoutwardliketheringsinapondintowhichastonehasbeenthrown.Astheobjectmovesintothegas,itsmoleculescompressintoasmallerspace.

Astheobjectmovesoutofthegas,itsmoleculesdecompressintoalargerspace.Thispatternorwaveofcompressionanddecompressiontravelsoutwardfromthevibratingobjectthroughthegasandmanifeststhephenomenoncalled“sound.”Ifthereisnogas,asinaperfectvacuum,thentherewillbenopropagationofsound.

Soundlevelsintheeverydayworld

Thesound,ornoise,ofeverydaylifesurroundsusfromourbreakfasttohouseholdchores,work,andtravel.Soundiseverywhereanditsoccurrenceseemsanaturalpartofourenvironment.Sound,however,canalsobeused,notjustfordirectcommunicationasinspeechormusic,butalsoasaresourcetobeharnessedandthenappliedtoamethodofmeasurement.

UsingsoundSoundcanbeusedasameasurementtoolbecausethereisameasurabletimelapsebetweensoundgenerationandthe“hearing”ofthesound.Thistimelapseisthenconvertedintousableinformation.Ultrasonicsensingequipmenthastheabilitytogenerateasoundandthenthecapacitytointerpretthetimelapseofthereturnedecho.Itusesatransducertocreatethesoundandsensetheecho,andthenaprocessortointerpretthesoundandconvertitintoinformation.

Frequencyandwavelength

Vibrationofthesoundwavesisrelatedtotimeandiscalled“frequency.”FrequencyismeasuredinHertz(Hz)andreferstothenumberofcyclespersecond.Apuresoundwaveofaparticularfrequencyexertssoundpressurewhichvariessinusoidallywithtime.Onewavelengthorcycleisdefinedasthedistancefromonecompressionpeaktothenext.Thewavelengthofaspecificfrequencyisrelatedtothevelocityatwhichthesoundtravels:

ThenumberofcyclesthatoccurinoneseconddefinesthefrequencyinHertzatwhichthesoundisbeinggenerated.Forourpurpose,thefrequencyisconstant.Atbest,thehumanearcandetectsoundsrangingfrom20to20,000Hertz.Thesoundrangeabovethisfrequencyisknownasultrasonics.

MeasurementprincipleApiezoelectriccrystalinsidethetransducerconvertsanelectricalsignalintosoundenergy,firingaburstofsoundintotheairwhereittravelstothetarget,afterwhichitisreflectedbacktothetransducer.Thetransducerthenactsasareceivingdeviceandconvertsthesonicenergybackintoanelectricalsignal.Anelectronicsignalprocessoranalyzesthereturnechoandcalculatesthedistancebetweenthetransducerandthetarget.Thetimelapsebetweenfiringthesoundburstandreceivingthereturnechoisdirectlyproportionaltothedistancebetweenthetransducerandthematerialinthevessel.Thisverybasicprincipleliesatthemeasurementheartofthetechnologyandisillustratedinthisequation:

Thespeedofsoundthroughairisaconstant:344meterspersecondwithinanambientairtemperatureof20°C.Therefore,ifittakes58.2millisecondsfortheechotobedetected,wehavethisresult:

ThemediumandthemessageForanultrasonicmeasuringsystemtohaveanyvalue,itmustprovideaconsistentoutputvalueforthesamephysicallevelconditionsoveralongperiodoftime.Thisrepeatabilitydependsmostlyonconditionsofthesoundmediaandthetargetmaterial.Thevelocityofsound(344m/sec)isdeterminedthroughthestandardmediumofairandattheidealtemperatureof20°C.However,oftentheconditionsunderwhichultrasonicmeasurementoccurarenotidealastherecanbenumerousfactorsinfluencingthemedium,therebyalteringthesoundtransmissionspeedandaffectingmeasurement:

temperaturemediumtype(gas)mediumstratificationvacuum

SoundintensitySoundintensitydescribeshowmuchenergythereisinawaveofsound.Theunitsofsoundintensityarewattspersquaremeter(W/m2).Whensoundintensitiesarecomparedtooneanother,itisusualtousethedecibelasaunitofmeasure.TheratiooftwosoundintensitiesI1,andI2isgivenbythisequation:

Forsoundinair,theusualreferenceintensitychosenasthe0dBpointis0dB=10-12W/m2.Usingthatreferencepoint,120dBdescribesasoundintensitythatis120dBlargerthanthe0dBreferenceintensity,whichisanintensityof1W/m2.120dBisconsideredthethresholdofpainforthehumanear.Thedecibelscaleisusedbecauseofitsabilitytoeasilycomparesoundintensitieswhichmayvaryoveranenormousrangeofvalues.

SoundvelocityandtemperatureTemperaturechangesaffectthevelocityofsoundinair,andthevariationsintemperaturerequirecompensationtocalculateaccuratemeasurement.Ifthetemperatureoftheairbetweenthetransducerandthetargetisuniform,thencompensationisachievedandanaccuratemeasurementcanbemade.

Thetemperatureoftheapplication,orthemediumthroughwhichthesoundtravels,isrequiredtocalculatethevelocity.However,SiemensMilltronicstransducershavebuilt-intemperaturesensors,andatemperaturereadingistakeneachtimethetransducerisfiredtocompensatefortemperaturefluctuations.

Thischarttrackstheincreaseinthevelocityofsoundasthetemperatureincreases.

SoundvelocityandgasThevelocityatwhichsoundpropagatesinagasisconstant,aslongastherearenochangesinthegas.Thefollowingformulacalculatesthevelocityforagas:

Example

At(20Celsiusor293Kelvin),thevelocityofsoundis:

Notethatthespeedofsoundvarieswithabsolutetemperature.Inairatnormalambienttemperatures,whichisabout300K,achangeof1KorC(to301K)causesthespeedofsoundtoincrease:

SoundvelocityandpressureSoundvelocityinamediumexperiencingvariablepressuresiscalculatedusingthefollowingformula:

Thisformulasuggeststhatthespeedofsoundvarieswithpressureasitdoeswithtemperature.

Thevaporsaturationinairofvariouschemicalsmustalsobeaccountedfor.Thesaturationlevelisrelevanttothedifferentvaporpressuresofeachchemicalasillustratedinthenextchart.Notethatthecurvedlinesarefor100%saturationandthetruesoundvelocityisinbetweentheapplicablecurveandthatshownforair.

SoundvelocityandvacuumIfatreefallsinavacuum,doesitmakeanynoise?No.Soundrequiressomethingtovibrate,andinavacuum,thereisnomediumtovibrate.Thusanapplicationthatoperatesinavacuumhastorelyonanalternatetechnologyforlevelmeasurement.

SiemensMilltronicshasacomprehensivelineofradarinstrumentsfornon-contactingmeasurement,andathoroughrangeofcapacitanceinstrumentsandguidedwaveradarforlevelandinterfacecontactmeasurement.Allthesetechnologiesoperateperfectlywellinavacuum.

SoundvelocityandattenuationAttenuationreferstoadecreaseofsignalstrengthasitmovesfromonepointtoanother.Forsoundsignals,ahighdegreeofattenuationgenerallyoccurswheretherearehighlevelsofdust,humidity,orsteam.Attenuationalsooccurswheretargetmaterialsarehighlyabsorbentto

sound,foamforexample.Insuchapplications,impedanceandfrequencyselectionareessentialinordertotransferasmuchpoweraspossiblefromthetransducerintotheairandviceversa.

Wherethemediumbetweenthetransducerandthetargetisotherthanthenaturalcompositionofair,thevelocityofsoundcanalsochange.Ifthemediumishomogeneous,compensationcanbeachieved.If,however,themediumisstratifiedsothepropagationofsoundundergoeschangesinvelocityatvariouslevels,thenonlyanapproximationcanbemadebyusingtheaveragevelocityofthemediumtocalculatethedistancethatthesoundhastraveled.

SoundreflectionWhenasoundwavearrivesataninterfacebetweenmediaofdifferentdensity(e.g.airandwater),someofthesoundenergyisreflectedandsomeofitistransmittedthroughthesecondmedium.Theratioofenergyreflectedtoenergytransmittedisdependentupontheacousticimpedancesofeachmedia.Thegreatertheratioordifference,thegreatertheamountofenergythatwillbereflected.

Theangleofthereflectedsoundwave(onasmoothsurface)isequaltotheangleoftheincidentsoundwave,buttotheoppositesideofthenormaltotheplaneofthesurface.Ideally,formeasuringlevel,thisangleiskepttoaminimum.

Asurfaceisconsideredsmoothiftheroughness,expressedasthepeaktovalleydifference,is1/8orlessoftheincidentwavelength.Anyabsorptionofthesonicenergyisignoredforthisexample.

SounddiffractionDiffractionoccurswhenthesoundwavebendsaroundanobjectsuchthatthereislittleornoreflection.Foragivensizeobject,diffractiondecreaseswithadecreaseinwavelength(increaseinfrequency).

Soundpressurelevel(SPL)Soundpressurelevel(SPL)isthepressureofsoundincomparisonwiththereferencepressurelevelwherePrefisthereferenceforsoundpressureinair(20.4mPaat1KHz).TheSPLcanbemeasuredbyamicrophone.

SoundintensitychangesWhensoundpropagateswithinagas,itspreadsoutsothattheenergyitcarriesisdiffusedoveranincreasingareaasthewavetravelsfurtherfromitssource.Excludinglossescausedbyotherfactorsdescribedlater,soundintensitydecreasesataratethatisinverselyproportionaltothesquareofthechangeindistance.

Thatistosay,iftheintensityofsoundisXatapointlfromthesource,thentheintensitywillbeX/4atadistanceof2lfromthesource.

SummaryThesoundwavesareaffectedbymanyfactorswithintheapplicationenvironment,andtheapplicationengineermustalwaysverifythatalltheseconditionsareknownbeforesettinguptheapplication:

temperaturemediumabsorbency(dust,steam)mediumtypepressuremediumstratificationvacuumreflectivityofmaterial

SiemensMilltronicsultrasonicinstrumentationtacklesapplicationsthatinvolveoneormoreoftheseconditions.Ourexperiencedsalesapplicationengineerswilldesignaninstrumentconfigurationthatwillprovidereliableandaccuratemeasurement.

1VanMorrison,“JoyousSound.”APeriodofTransition,1977.2Felton,Bob.“LevelMeasurement:AncientChore,ModernTools.”ISA,August2001.3ModulevelisaregisteredtrademarkofMagnetrol.4®RaytheonisaregisteredtrademarkoftheRaytheoncompany.5®MilltronicsisaregisteredtrademarkofSiemensMilltronicsProcessInstruments.

ChapterTwo

UltrasonicinstrumentationStop,children,what’sthatsound1

Measurementrepeatabilityisdependentonthesignalprocessorbeingused.Thespecifiedaccuracyvaluestakeintoaccountsuchfactorsaslossofresolution,supplyvoltagevariation,operatingtemperature,circuitlinearity,andloadresistance.Thesefactorsdependontheinstrumentationhardwareandsoftware,nottheapplicationconditions.

Ultrasoniclevelmeasurementinstrumentationrequirestwocomponents,onetogeneratethesoundandreceivetheecho(transducer),andonetointerpretthedata,deriveameasurement,andaffectareactionofthecontroller.Eventhoughsomeultrasonicinstrumentscombinethecomponentsinoneunit(SITRANSProbeLU,PointekULS200),theindividualfunctionalityremainsdistinct.Theoperationandtechnicalspecificationsregardinginstrumentperformancewillbediscussedindetailinsubsequentchapters.

ThetransducerAdvancesinthedesignofultrasonictransducershavesignificantlycontributedtothesuccessofultrasonicsasalevelmeasurementtechnology.Transducersarethevocalchordsandearsofanultrasoniclevelmeasurementsystem.Thesoundpulseiscreatedbythetransducerwhichconvertstheelectricaltransmitpulseintosonicenergy,effectivelyradiatingthatsonicenergyintotheairandtowardsatarget.

Afterthetransmissionprocessiscomplete,thetransducerthenactsasthereceivingdeviceforthereturningechosignal.Thisinformationisthenprocessedandturnedintoameasurementvalue.

Theeffectiveacousticenergyisgeneratedfromthefaceofthetransducerandisradiatedoutward,decreasinginamplitudeatarateinverselyproportionaltothesquareofthedistanceastheunitenergyisdissipatedoveralargerarea.Maximumpowerisradiatedaxially(perpendicular)tothefaceinalinereferredtoasthe“axisoftransmission.”Whereoff-axispowerisreducedbyhalf(-3dB)withrespecttoanon-axispointequidistantfromthetransducer,aconicalboundaryisestablished.Thediametricalmeasurementoftheconeindegreesdefinesthehalf-powerbeamangle.Althoughthebeamangleforaroundfacetransducercanbederivedempirically,itcanbepredictedbythefollowingformula:

TransducerenvironmentsTransducerscarryafullrangeofhazardousapplicationapprovalsfromCSAandFMtoATEX(EuropeanUnionExplosiveAtmospheresprotection).Constructedfromthemostadvancedmaterialcompounds,transducersareavailableforsomeoftheharshestindustrialenvironments:

Forcorrosiveapplications,transducersarefabricatedwithmaterialssuchasPVDForPTFE,allowingultrasonicstobeusedwithacidsandsolvents.Industyapplications,acousticimpedancematchingmaterialssuchaspolyurethaneandpolyethylenefoamareusedbecausetheirelasticpropertiesamplifythecrystal’svibration.

Forlong-rangesolidsapplications,long-rangetransducersdeliverhighpoweroutputtomeasuresolidmaterialsaccuratelytodistancesover200feet.Theflexuralmodetransducerdeliversmorepowerbydrivingalargecentraldiscwiththecentralpiezoelectriccrystal.Thelargemetaldiscismadetovibratealongwiththepiezoelectriccrystal,producingastandingwaveonitssurface.Holespunchedinconcentricringsalloweveryotherantinodetobedelayedtothepointthattheybecomeinphasewiththeothers.Theneteffectisanintensesoundpressurewavewhichistransmittedintotheair.Thistypeoftransducerisverywellsuitedfordustyenvironments.

TransduceraccuracyTheaccuracyofanyinstallationisdependentonthecaretakentoensuretheelectronicsagreewiththephysicalmeasurementandtheaccuracyofthiscalibration.Duetothedesignoftheelectronics,insitucalibrationiseasyandhighaccuracyisreadilyobtainable.Traceabilitytoknownstandardsisdependentonthemethodandequipmentusedasthereference.

TransducerresolutionandaccuracyTheminimumchangeorincrementofdistancethatcanbedetectedisreferredtoastheresolutionofthemeasurementsystem.Resolutionisdependentonthewavelengthandthetimingresolutionoftheelectronics.Theshorterthewavelength,thesmallertheincrementthatcanberesolvedgivenaspecificsignalprocessor.TheSITRANSLUT400,hasadesignresolutionoflessthanonemillimeter(0.078")andaonemillimeteraccuracyspecification.

Inscience,engineering,industryandstatistics,accuracyisdefinedashowclosethemeasurementsystemquantityistothemeasurementofthatquantity’sactualvalue.

Impedancematching

Thevibrationofthetransducerfaceactsuponthesurroundingairtoproduceasoundwave.However,forefficienttransferofpowerfromthecrystaltotheair,impedancematchingmaterialsmustbeused.Matchingmaterialstepsdownthehighimpedanceofthecrystaltothelowimpedanceofair.OnSiemensMilltronicstransducers,aspeciallowdensitymaterialisusedasaninterface.

Theimpedancematchingcanbefurtherenhancedbyanadditionalfacingmaterial.However,thisisnotalwaysrequirednorpracticalfromanapplicationstandpoint.

Acousticimpedancematchingisimprovedbythesematerialsastheirelasticpropertiesamplifymagnitude(D)ofthecrystal’svibration.Asexpressedbythisformula:

Moreamplitudeisnowpossiblewithagivenforcebyincreasingthedistancethevibrationhastraveledthroughthetransducerface.

AxisoftransmissionSoundenergyisgeneratedfromthefaceofthetransducerandradiatesoutward.

Theenergygeneratedatthefaceofthetransducerdecreasesinamplitudeatarateinverselyproportionaltothesquareofthedistancetraveled.Maximumpowerisradiatedaxially(perpendicular)tothefaceinalinereferredtoasthe“axisoftransmission.”

BeamwidthBeamwidthisdefinedas“twicetheangleatwhichoff-axistransmissionis3dBlessthanthetransmissionaxisacousticpressurelevels(asmeasuredequidistantfromthetransducerface).”Therefore,adiametricalpowermeasurementoftheconeindegreesdefinesthehalf-powerbeamangle.

Beamwidthisafunctionofthetransducerradiatingsurfacearea,frequency,andplane.

Forultrasoniclevelmeasurement,widedispersionisundesirable.Thenarrowerthebeamwidth,thelesslikelyvesselobstructionswillbedetected.

Forshortandwidevessels,a12°beamwidthisidealtosimplifyaiming.Fortall,narrowvessels,a5°to6°beamwidthwillavoidvesselwallseamorcorrugationdetectionformaximumreliability.

BeamspreadingAswellasthemainbeam,sidelobesofamuchlowerintensitymayradiateintheformofaconicalshell,concentrictothemaincomponent.Themaincomponentandthesidelobesmaybedepictedonapolarplotinordertovisualizethepatternofsound.Itisdesirabletohaveasmuchenergyaspossibleconcentratedinthemainbeaminordertoreduceunwantedechoesgeneratedfromthesidelobes.Similarly,itisnecessarythatenergybepreventedfromradiatingfromtheendoppositethetransducerface.Aswellasgoodoutputpower,thetransducermustbesensitivetotheweakreturnechoesasnoamountofelectronicscan

compensatefornon-detectionofanecho.Thus,propertransducerdesignisfundamentallyimportantinputtingthetheoryofultrasonicechorangingintopractice.

RingdownTheprimaryactivecomponentofthetransducerisapiezoelectriccrystalthatexhibitsanexpansionandcontractionofitslengthwhensubjectedtoalternatingvoltage.Whenthevoltageisremoved,thecrystalisnolongerexcitedanditsmechanicalvibrationbeginstodecay.Theinherentnatureofthecrystalandthesurroundingtransducermassistocontinuevibrating.Thisvibrationiscalled“ringing.”Thetimeittakesforthisringtostopisoftencalled“ringdown.”

Thelevelofringingdependsnotonlyonthecrystalitselfbutalsoonthematerialsandconstructionoftheentiretransducer.Moderntransducershavesignificantlylessringdownthanearlierversions.Duetoresearchintothelatestconstructionmaterialsandtechniques,theblankingdistanceofthenewestultrasonicinstrumentsliketheSITRANSProbeLUisnowonly0.25meters(10").

Thecontrollers

Thetransducerscanbelikenedtothescoutsofalevelmeasurementsystem.Theygooutandgettheinformationandbringitback.Thecontrollersanalyzethatinformationandthenturnitintosomethinguseful.

Sinceitsinception,ultrasoniclevelmeasurementtechnologyhasimprovedgreatlywithadvancesinelectronicsignalprocessors.Digitalsystemstransmitinthesamemannerasanalogsystems,butdigitizetheanalogreceivedsignalofthereturnechoandstorethecompleteechoasaprofile.

Theprocessor,insidethecontroller,thenanalyzestheprofileusingsoftwarealgorithms,extractingoneechofromtheprofileasthemostprobabletobethetargetecho.Then,thesignalprocessorconvertsthetimedifferentialbetweenthetransmitandthetimeoftheselectedtargetechointodistance.

Digitalultrasonicmeasurementalsohastheabilitytousesoftwarefilteringtechniquesandintelligentechoextractionalgorithmstodeterminedistance.Themicroprocessorgivesthesignalprocessortheabilitytoperformhighspeedmanipulationofthedatagatheredfromanechoprofile.Usinganalog-to-digitalconversion,echoprofilesreceivedbythetransduceraredigitizedbythereceivingdeviceandstoredinmemoryforfutureevaluation.Storingtheechoprofileinmemorymakesitpossibletoperformthemanytestsonthedatanecessarytodeterminethetruematerialecho.

DigitalfilteringDigitalfilteringremovesunwantednoisefromtheechoprofile,includingelectricalnoisealwayspresentinanindustrialenvironment.

Forexample,variablespeedmotordrivesproducehighlevelsofelectricalnoisethatareusuallyveryhighinamplitudeyetveryshortindurationwhencomparedtothedatabeinggatheredfortheechoprofile.Therefore,digitalfilteringisusedtoremoveanydatafromtheprofilebelowagivenlimitinduration,significantlyreducingtheeffectofthenoiseontheoverallmeasurementquality.

AveragingechoesInapplicationsthatcreatehighlevelsofdustoracousticnoise,highspeeddatamanipulationpermitstheaveragingofmanyechoprofilestodevelopacompositethatcanbemoreaccuratelyanalyzed.Averagingofechoprofilesperformsseveralusefultasks:randomsourcesofinterferencesuchasacousticnoiseoraircurrentsareaveragedoutoftheechodataandechoesareenhancedindustyandotherwisechallengingapplications.

EchoextractionalgorithmsEchoextractionalgorithmsaresoftware-basedfunctionsusedtoevaluateanechoprofile.Anechoprofilecanbeevaluatedinmanyways,witheachmethodhavingparticularadvantagesindifferentapplications.Beforemicroprocessors,analogsignalprocessorsevaluatedtheechoprofileasitreturnedandthenthereceiverlookedforanyechoaboveasetthreshold.Onceanechoofsufficientamplitudewasdetected,thedistancewascalculatedandtheoutputwasgenerated.Unfortunately,analogsignalprocessorswereunabletodifferentiatebetweenrealbuterroneousreturnsandthetrueechoindifficultapplications.

Digitalsignalprocessorsapplyechoextractionalgorithmsaftertheentireechoprofilehasbeenreceived,andthenusemanytechniquestodeterminewhichechorepresentsthetruemateriallevel.

Onemethodofechoextractioninvolvesstoringaprofileoftheemptybin.Thisstoredprofileisthenusedasatemplate,allowingtheprocessortoignoreobstructionsinthebin.Forexample,inabinfabricatedwithbracingaroundtheinsidesurface,thereturnechoescanindicatebracingandnotlevel.Whentheechoprofilefortheemptybiniscaptured,theprofileshowsechoreturnsindicatingthebracings.Inordertodiscriminateagainsttheseerroneousechoes,thesignalprocessorcompareseachechoprofiletothetemplateprofileinitiallytakenandstoredinmemory.Thistemplateprofilecontainstheechoesproducedbythebracing.Thus,usingthiscomparison,theechoesfromthebracingareignoredandthetruematerialechoisselected.Anothermethodevaluatestheechoprofilebasedonthecharacteristicsoftheechoanditslocationintheechoprofile.Thismethodfirstselectsthemostlikelyechointheprofilebyusingathresholdsimilartothatusedbytheanalogsignalprocessor.Oncethemostlikelycandidateshavebeenselected,thealgorithimsbegintoevaluateeachechobasedonthetypeofmaterialbeingmeasured.Ifthematerialisliquid,thentheprogramevaluatestheechoonamplitudeanditslocationintheechoprofile.Forexample,whenmeasuringaliquidsurfacethecharacteristicechoisnarrowandhighinamplitude.Liquidisveryreflectivetoultrasonicfrequencies;therefore,thetrueliquidlevelwillusuallybethefirstechoreceived;andinaliquidapplication,thealgorithmwouldselectthefirstechoreceivedwiththehighestamplitude.Forsolidsmeasurement,theprocessorselectsthemostlikelyechoesinthesamemanner,onlyusingdifferedselectioncriteriabasedonthedifferingcharacteristicsofthatsolidmaterial.Inthiscase,theprogramlooksforanechowhichisoflesseramplitudeandwiderthanthatofaliquidecho.Theechoiswiderbecausemostsolidmaterialshaveanangleofreposewhichreflectsmanydifferentechoesfromdifferingpointsontheangleofrepose.Thealgorithmmustnowlookfortheselectedechowhichisthehighestinamplitudeandthewidest.Therefore,theprocessorwillselecttheechowiththegreatestarea.

SummaryDigitalsignalprocessingandadvancedechoextractionalgorithmsmakeultrasonicsareliableandaccuratemethodofmeasuringsolidsandliquids.Ultrasonicinstrumentationisthusavaluableadditiontomanyoperations,providinglongtermandcost-effectivemeasurement.Thisbookprovidesathoroughlookatultrasonicleveltechnology,attheinstrumentation,andatthewidevarietyofapplicationsbestsuitedforitsuseasthisproventechnologycontinuestobeapreferredsolutiontomanymeasurementneeds.

1BuffaloSpringfield,“ForWhatIt’sWorth.”BuffaloSpringfield,1967.

ChapterThree

ThesoundandtheslurrySomebody'sshoutingUpatamountain

Onlymyownwordsreturn1

Thetransduceristhespeakerandmicrophoneintheultrasoniclevelsystem,producingtheultrasonicwavesandthensensingtheechoesastheyreturnsothecontrollercanrespondasprogrammed.SiemensMilltronicstransducershaveaprovenandextensiveapplicationhistory,andarethereliableeyesandearsofthousandsofapplicationsaroundtheworld.

Thischapterexaminestheroleofthetransducerinanultrasonicsensingsystem,howitismade,andhowitworks.

Topicsultrasonicsystemstransducersblankingdifferentialamplifiersechoprocessingreducingnoisebeamangleprofiles

TransducersandultrasonicsystemsTheultrasonicsensingsystemisavailableintwoformats:

singlesystems:thetransducerandthecontrollerelectronicsareintegratedintooneenclosure

compoundsystems:thetransducerandthecontrollerareseparateentities

SinglesystemsAsingleunitsystemisoftenreferredtoasa“leveltransmitter.”TheSiemensSITRANSProbeLUleveltransmittercombinestheelectronicsandtransducerinacompactsystemideallysuitedforliquidlevelmeasurementupto12meters(40ft).

ThetransducerportionoftheSITRANSProbeLUisinthelowerhalfofthedevice;thecontroller,electronicsandwiringareaareintheupperhalf.Leveltransmittersareversatileandaresuitableformanyapplications,includingbothgeneralpurposeuseinsafeareasanduseinhazardousareas,dependingonapprovals.

CompoundsystemsCompoundsystemsseparatetheultrasonictransducerfromthecontroller.Thetransducerismountedonthevesselwhilethecontrollerisinasafeareaawayfromtheapplicationinacontrolroomorafieldmountedelectricalpanel.Siemensoffersawidevarietyofcontrollersandtransducers,liketheSITRANSLUT400andEchomaxXRS-5,thatcanbematchedtosuitmanyapplications.

Transducerscarrymanysafetyapprovalsformountingandforuseinhazardousareas,andtheyaredesignedtowithstandruggedindustrialenvironments.Thetransducerisconnectedtothecontrollerbycable(eitherco-axialortwistedpair),receivestheelectricaltransmitpulse,andthensendsthereturnechopulsealongthesamewire.Thetransducerandcontrollercanbeseparateduptoadistanceof365meters(1200ft).

TransducersAtransducerissimplyadevicethatconvertsoneformofenergyintoanother.Thus,devicessuchasthespeakersconnectedtoanentertainmentsystemaretransducersbecausetheyconvertelectricalsignalsgeneratedbytheamplifierintothemusicyouhear.Amicrophoneisthereverseofaspeaker:atransducerconvertingsoundintoelectricalsignals.

Thetimerequiredtochangefromtransmittoreceivemodeisfinite.See“Blanking."

Theultrasonictransducerperformsbothfunctions.Likeaspeaker,itconvertsthehighfrequencyelectricalpulsefromthecontrollerintohighfrequencysound,andthenprojectsthesoundintothevessel.Andlikeamicrophone,itconvertsthesoundechobackintoanelectricalpulse,transmittingthissignalbacktothecontrollerforprocessing.Thetransducerdoesnottransmitandreceivesimultaneously,butconstantlychangesfromtransmitmodetoreceivemodemanytimespersecond.

Theheartoftheultrasonictransducerisapiezoelectricceramiccrystalthatvibrateswhenahighvoltagepulseisapplied,sendingoutsoundwaves.Conversely,whenthesoundwavesreturn,thevibrationscausethepiezoelectriccrystaltoproduceanelectricalsignalwhichisthensentbacktothecontrollerforinterpretation.Thedifferencebetweenthe

transmittedsignalandreceivedsignal,issignificant,andtheoutgoingtransmitcanbeseveralhundredvolts,whilethereceivedsignalisinthemicrovolttomillivoltrange.

Becausethereturnsignalissoslight,itcanbeaffectedbyanynumberofsituationalinfluences:mediumtemperatures,attenuation,andobstructions.Toachievemaximumperformancebenefitfromtheultrasonicsystem,alltheapplicationconditionsneedtobeconsideredwhendesigninganultrasoniclevelsystem.

TemperatureandtransducermaterialThetemperatureoftheapplicationcanaffecttheperformanceofthetransducer,asdoesitsconstancy,becausefluctuationsalsoaffectthereadingreliability.Transducerscompensatefortheseconditionsbyincorporatingtemperaturesensorsandbyusingtemperatureresistantmaterialsintheirconstructionsothatthereadingsareunaffectedbytheseconditions.Thetemperaturevariationeffectisgenerally0.17%foreverydegreecentigrade;soforeverydegreetheapplicationtemperaturefluctuates,thelevelmeasurementisaffectedby0.17%.

TemperaturesensorsWhentransducerswerefirstdeveloped,temperaturevariationsweremediatedbytheuseofanexternalsensorwhichtransmitteddatatothecontroller,whichthencompensatedforfluctuationsbyadjustingthereadingaccordingly.Theneedfortheexternalsensorwaseliminatedwhenanambientairtemperaturesensorwasincorporatedintothebodyofthetransducer.Makingthesensorpartofthetransducercircuitryalso

allowsthesensortousethesamewiresettotransmittemperaturedatatothecontroller.Siemensaddedtothisconveniencebyplacingthetemperaturesensorinapocketjustbehindthetransducerfaceandbyimprovingthecircuitry,enhancingsensorfunctionbyacceleratingthetemperatureprocessing.

Built-intemperaturecompensationimprovestheaccuracyofthesystemandreducesinstallationcost.

SoundanddifferentialamplifiersWhilenoisecanaffectthesystemfromoutside,itmayalsooccurwithinthesystemitself.Thisinfluenceisaconsequenceofthesystem'selectricalfunctionalityandthecablingrequirementsthatcreateoramplifynoise.Siemenshasdevelopedadifferentialreceiverinterfacethateliminatesorgreatlyreducesinducednoiseonboththepositiveandnegativewiresofatwistedpaircable.2

Transmissionandreceiptofbothelectricalandultrasonicsignals

Figure1:Theelectricalpulsesreceivedbythetransceivertendtobesmallerthantheinitialpulsesoutputbythedevice.

Therefore,accuratedistancemeasurementrequiresamplificationoftheelectricalsignals.

Forthedevicetocalculateadistanceaccurately,itmustamplifythereturningelectricalpulsesandanalyzethereturneddatausingechoprocessingalgorithms.Unfortunately,theamplificationprocedureusedonthereturningsignalsissensitivetotheeffectsofnoiseandthisiswherethedifferentialreceiverinterfacehasanumberofadvantagesoverthecommonsingle-endedreceiverinterface.

Single-endedreceiverTheamplifierwithinthecontrollerisresponsibleformagnifyingthereturningelectricalpulsesexistingbetweentheamplifier’spositiveandnegativeinputs.Forthecommonsingle-endedreceiverinterface(seeFigure2),thepositiveinputoftheamplifierisconnectedtothepositiveterminalofthetransducer,andthenegativeinputisconnectedtoground.Whenthedevicereceivessignalsfromthetransducer,itamplifiesthesignalexistingatthepositiveterminalwithrespecttoground.Fornow,ifthegroundisassumedtobeideal,theoutputoftheamplifierwillsimplybeamagnifiedversionofthesignalreturningalongthepositiveterminal.

Commonsingle-endedreceiverconnection

Figure2:Inacommonsingle-endedreceiverconnection,thepositiveinputoftheamplifierisconnectedtothepositiveterminalofthetransducerandthenegativeinputisconnectedtoground.

Intheeventwherethesignalalongthepositiveterminaliscontaminatedbynoise(i.e.environmentalnoiseproducedbymotors,near-byantennae,wirelessdevices,etc.),sincethegroundisassumedtobeideal,theamplifierwouldmagnifythisnoise(seeFigure3).Thisnoisecouldleadtoinaccuratedistancecalculationsbythedevice.

Theeffectsofnoiseonacommonsingle-endedconnection

Figure3:Theeffectofnoiseonacommonsingle-endedconnectionismagnifiedandmayleadtoinaccuratedistancecalculationsbythetransceiver.

DifferentialreceiverInthedifferentialreceiverconnection,thevoltageexistsbetweenthepositiveandnegativewiresofthecable.Thepositiveinputoftheamplifierconnectstothepositiveterminalofthetransducerandthenegativeinputconnectstothenegativeterminal.

Differentialreceiverconnection

Figure4:Inadifferentialreceiverconnection,thepositivewireisconnectedtothepositiveterminalofthetransducersandthenegativeinputisconnectedtothenegativeterminal.

Wherethepositiveandnegativewiresareinverycloseproximitytoeachother(common),anyenvironmentalnoiseoccurringononewirewillalsoexistontheother.Sinceadifferentialamplifiermagnifiesthedifferencebetweenthetwowires,anynoisecommontobothwires(hencetheterm“common-mode”noise)willnotappearattheoutputoftheamplifier(seeFigure5).

Theeffectsofnoiseonadifferentialconnection

Figure5Becauseadifferentialamplifiermagnifiesthedifferencebetweenthetwowires,anynoisecommontobothwireswillnotappearattheoutputoftheamplifier.

WhenaconnectionbetweenadevicewithadifferentialreceiverinterfaceliketheSITRANSLUT400andatransduceristobemade,ashieldedtwisted-paircableshouldbeused.Inthiscase,thepositivewireconnectstothepositiveterminalofthetransducer,thenegativewireconnectstothenegativeterminal,andtheshieldconnectstoground.Notethatneitherthepositivenorthenegativeterminalsarelinkedtoground.Sincethepositiveandnegativewiresaretwistedtogether,thereisahighlikelihoodthattheenvironmentalnoiseexistingonbothwireswillbe

essentiallythesame.Therefore,environmentalnoisewillbepresentintheformofcommon-modenoise,whichtheamplifierwillbeabletoeffectivelyremove.Alsovoltagesinducedontheshieldduetogroundloopswillhavenoeffect,sincethesignalexistsacrossthepositiveandnegativewires.

Differentialinterfacecombinedwiththephysicaltwistingofthewiresinthetwistedshielded-paircableenhancesthecommon-modenoiserejectionability,helpingtonegatenoiseinterference.

Applicationtemperature3

Ultrasonicinstrumentshaveahightemperaturetolerance.Formostapplications,hightemperatureisnotanissue,butinhotprocessapplicationswherethematerialcomesfromakilnordryer,thetransducerrequiresahightemperaturetolerance.Tomeetthesedemands,designadvanceshaveextendedthemaximumtemperaturerangeofmanytransducersto150°C(300°F).

Ultrasonictransducersremainextremelystableovertheiroperatingrangebecauseoftheiron-boardsensorsandtwo-wiredatatransmission,evenduringextremetemperaturefluctuationscommontomanyoperations.

HousingmaterialChemicalcompatibilityisanimportantapplicationconsideration;thetransducerhastobecompatiblewiththematerialbeingmeasured.Transducersareavailableinavarietyofmaterials,includingPTFE,ETFE,PVDF,CPVC,andCFM,andcanbematchedwithavarietyofapplicationmaterialconditions.

Attenuationisthedecreaseinthesoundsignalasitpassesthroughvariousmediaandtheinitialpower/vibrationofthesoundisabsorbedbyotherinfluences.

Theusershouldalwaysverifymaterialsuitabilitybycontactingthetransducermanufacturerorbyusingachemicalcompatibilitychartprovidedbythetransducermaterialmanufacturer.ChemicalcompatibilitychartsarealsoreadilyavailableontheInternet.

RangeandpowerThemaximumrangeofatransducerisnormallyproportionaltotheamountofpoweravailableandthefrequencyoftransmission.Thehighertheinitialtransmitpower,thebetterthechanceofgettinganecho.Thethickerthemediumthroughwhichthesoundtravels,themoreforceisrequiredtopushthesoundthroughit.Lowerfrequenciesarelessattenuatedwhentheypassthroughair,whichiswhyfoghornsaresolow-pitched.

Rangesquotedinthespecificationsheetsandinstructionbooksshouldbetakenasamaximum.Donotexceed!

Thematerialspresentinthemediumabsorb(attenuate)thesoundandaffectperformance.Thisgraph4showstheattenuationindecibelsofvarioussoundfrequencieswhenthetemperatureandhumiditylevelsareconstant:

Soat41kHz,theroundtripattenuationisapproximately55dBatarangeof15meters(50ft).Anechoof30dBatthemaximumratedrangeofatransducerisstrongenoughtoprocessandexceedthenoiselevelsinherentinmanyapplications;however,insomeinstances,echoesasweakas5dBcanbeprocessedwithhighconfidence.Knowingthis,thecontrollermustsendoutapulsetothetransducerthatisstrongenoughsothatintheafter-round-tripattenuationof55dBat41KHzata15meterrange,thereissufficientreturnechostrengthtoprocessthesignal.

Long-rangetransducersaredesignedtooperateatlowerfrequenciestotakeadvantageoflowerattenuationratesthatprovideastrongerechotothetransceiverforprocessing.Inexchangefortheextrapower,however,someresolutionislost.Butinlong-rangeapplicationsofgrains,powders,orpellets,thisgenerallydoesnotpresentaproblemasaccuracyrequirementsmaynotbeasstringent.

ConditionsConditionsaffectperformancebecausethesoundwavesneedtogothroughthemediumandareinfluencedbyotheroccupantsofthatspace.Dust,steam,andhighhumidityattenuatesoundandtherequireddistanceformeasurementmaynotbemet.Withoutanecho,thereisnothingfortheelectronicstoworkwith.Conversely,withaverysmallstainlesstank,itmaybebettertogotoalowerpowertransducerbecausemultipleechoesmayrequirechangingthealgorithm,aninconveniencetothecustomer.

Rule:iftheapplicationisonthelimitofthetransducer’srange,stepuptothenexttransducerforbetterreliability!

Mostsolidapplicationsaredusty.Inareaswheredustisextremelyheavy,keepingthetransducercleaniscriticalbecausematerialbuildupreducesthetransducer’sabilitytotransmitandreceive.Siemenstransducersusematerialswithgoodreleasecharacteristicswhich,combinedwithpulsatingdisplacement,oftenpreventbuild-upfrombeginning.

StillingwellsIfanapplicationisveryagitated,dusty,orhasalotofsurfacefoam,theseconditionsmaybeneutralizedusingastillingwell.Thestillingwellisasecondarypipeaccessingthetankcontentsandreflectingthesamecontentlevel.

Inaverysmallstainlesstank,gotoalowerpowertransducerbecausemultipleechoesmayrequirechangingthealgorithm.

Withstillingwells,lowerpowermaybebettersincethereisnospreadinglossbecausethesonicenergyiscontainedwithinthepipe.Inlaboratoryconditionsequivalenttoanemptywarehouse,oroutsideonacalmday,echoeshavebeenobtainedatmuchgreaterdistancesthanthenominalratingofthetransducers.However,inreal-worldapplications,usetheguidelinesdetailedabove.

Foamfacing

Impedancematchingfoamfacingcanimproveatransducer’spowerandrange.Impedancematchingprovidesgreateracousticpoweroutputandisveryusefulindustysituationswheretheparticlesintheaircauseattenuation.

Animpedancematchingpolypropyleneclosed-cellfoamfaceisdesignedforEchomaxXPStransducers.Theclosedcellpolypropylenehasahightemperatureratingof95°C(203°F)andisnotbotheredbydustormoisturegettingintothefoam.

MoistureontransducerfaceThefaceoftheXPStransducersisactiveandwillultrasonicallyevaporatethedroplets.Ifthereisabitofaslopetothetransducer(mountadegreeortwooffvertical),theextravibrationwillcausethedropletstomovetotheedgeandfalloff.

TransducerselectionSelectingtherighttransduceraffectsperformance,andthecriteriashouldbebasedonrange(distance)andpower.Forexample,insomepowderandplasticpelletapplications,ashorterrangeEchomaxXPS-15(operatingat44KHz)ismoreappropriatethanalong-rangeEchomaxXPS-40(operatingat21KHz)becausethehigherfrequencyyieldsabetterreflectionfromthematerialsurface.Alltheapplicationconditionsneedtobeconsidered,notjustdistance.

BlankingdistanceandheightplacementThelocationofthetransduceralsoinfluencesperformance.Theheartofatransducerisapiezoelectriccrystal;whenatransducerissentatransmitpulse,thepiezoelectriccrystalexpandsandcontractslengthwisetoproducetheultrasonicsoundsignal.Whenthetransmitpulsestops,thecrystalisnolongerexcitedanditsmechanical

vibrationbeginstodecay.Thisdecayhasafinitetimeperiodandisoftenreferredtoas“transducerringdown”duringwhichthetransducercannotreceiveanecho.

Properaiming,location,andmountingareotherimportantfactors.

Thetimeoftheringingisthenconvertedtodistance(D=VT)andrepresentsthespaceinfrontofthetransducerfacewheremeasurementisnotpossible.Thisspace,alsoknownasthe“blankingdistance”or“deadzone,”hasdecreaseddramaticallyovertheyearsastechnologyandresearchadvancedultrasonicmeasurementtechnology.Initially,theblankingdistancewasameterorevenmore,butithasbeenreducedto25centimeters(0.82ft)inthemostrecentsystems.

Otherfactorsliketemperatureandinstallationtechniquesalsoaffecttheblankingdistance:

Theringdownquantitydependsonthecrystalitselfaswellasthematerialsandconstructionoftheentiretransducer.

TemperatureHightemperaturetransducershavealongerblankingdistance.Whileringdowntakesthesameamountoftimeregardlessofthetransducer’stemperature,thespeedofsoundincreaseswithtemperature.ThereforewhenusingD=VT,agreatervelocityresultsinanincreaseddistance.Theblankingdistanceisstatedatthemaximumtransducertemperaturerating.

InstallationIfthetransducerisconnecteddirectlytoametalcouplerorifthemountingthreadsaretorquedtootightly,themountingarrangementactsaspartofthetransducerandwill“ring”witheachtransmitpulse.Toreduceringingonly,hand-tightenthetransducerintoablindflangeorontoaconduitadapter.Ifpossible,useaplasticconduitadapterratherthanametalone.

Foraflangedtransducer,usethesuppliedplasticboltsanddonotover-tighten.Useagasketbetweenthevesselflangeandthetransducerflange.

Transducerdesign:theheartofthematterThephysicaldesignoftoday’stransducerhousesdecadesofresearchandenhancements,distinguishingSiemensfromtherestoftheplayers.ThesetransducerdevelopmentshavemadeSiemensthebestinthebusinessandtheworldleaderinthefield.

Measuringdistanceisnotassimpleastimingthesoundwhenitbouncesback.Italsorequiresintelligencebecausesoundisindiscriminate.Itbouncesfromanythingandeverything,andsincemostapplicationsarefilledwithobstructionsandotherclutterthatinterfereswiththepathofsound,itrequiressophisticatedequipmenttodistinguishthereallevelechofromtherestofthebouncebacks.

Siemensultrasonicinstrumentationhasthesophisticatedtechnologythatevaluatestheechoesanddetermineswhichonesaretrueandwhicharefalse.

SummaryThetheoreticalprincipleofsoniclevelmeasurementissimple.Atransducerlocatedatthetopofabinorwelltransmitsapulseofsoundenergy.Thesoundreflectsfromthematerialsurfaceandtravelsbacktothetransducerwhereitisconvertedintoanelectricalpulse.Thetimedelayfromtransmissiontoreceivedechoisconvertedintodistanceandthemateriallevelisdetermined.

Inpractice,soniclevelmeasurementisabitmorecomplicatedasthereisnotjustasingleechofromthematerial,butmanyechoesreflectingfrombinwalls,beams,pipes,andwiresinthesoundpath.Furthermore,theactualechoqualitiescanvarygreatlyforthefollowingreasons:

soundattenuateswithdistance;thus,thedesiredechofromthematerialsurfacemaybeweakerthantheundesiredechoesthematerialsurfaceofsolidsisusuallyinclined,andthisspreadsandweakenstheechoelectricalnoisefrommotorsorcontrollerscaninterfereorbestrongerthantheecho

Distinguishingamongthemanyechoescanthusbeverydifficult,butitiscrucialforthesystemtobeeffectiveandtherealechoneedstobefound.Thehistoricalprogressionofthetechnologyisbasedonthissearchforthetrueecho.

1DeepPurple,"PicturesofHome."MachineHead,1972.2Thissectionwasfirstpublishedas,Ausder“Klemme”Füllstandmessung-intelligenteSchaltungstechnikvergrößertRauschabstand.GordonLi.MSRMagazin(Messen,Steuern,RegelnundAutomatisieren).Issue1-2(January/February2005)pages:16-17.3DougDuncan.“Ultrasonicsensors:Nowanevenbetterchoiceforsolidmaterialdetection,”InstrumentationandControlSystems.November1998.4From“TheTheoryofUltrasonicsandEchoRanging.”

ChapterFour

EchoprocessingMakinggooddecisionsisacrucialskillatanylevel.1

Ultrasonicstechnologyhasbeenusedforindustrialbinlevelmeasurementsincethe1940s.Sincethen,thetoolshaveevolvedtoovercometheacousticproblemsfacedinrealworldapplications.Complexcircuitrywithtimevaryinggain,automaticgaincontrol,rangetrackinggates,nearandfarblanking,noisesuppressionfilters,phaselockedloops,andotheradvanceshaveexpandedthecapabilitiesofsoniclevelmeasurement.Thesedevelopmentsallhaveonethingincommon:real-timeanalogprocessingofthesignalasitwasreceived.

Whileanalogprocessinggreatlyadvancedultrasonictechnologyaslevelmeasurementinstrumentation,italsohadtwomaindisadvantages:

First,askilledtechnicianwithascrewdriverandanoscilloscopewouldcarefullyadjusttheinstalledelectronicsforeachapplication,andthishadtobedonewhilethebinlevelwascycledupanddownseveraltimes.Thisisacostlyandtime-consumingprocess.Second,sincethesignalisprocessedasitisreceived,thereisnoopportunitytoanalyzeandcomparetheinformationstatisticallytoseeifitisevenpossibleorcorrect.Thusdataloggingwasnot

possible.

Siemensrecognizedthatanalog-basedinstrumentswouldneverbesufficientandfocuseditseffortsonmovingawayfromreal-timeprocessing.Engineerssoonrealizedthatplacingtheentirestreamofechoesintoastoredechoprofileinacomputer’smemorygavetheunittheopportunitytoexamineitsshots.Thecomputerthenprocessesandanalyzesthestoredechoprofiletoselectthetrueechoinamorereliablefashion.ThefirstproducttousethisrevolutionarytechniquewastheMilltronicsAiRangerIV,introducedin1984,andthissystemhasbeenineveryinstrumentsincethen,includingSITRANSLUT400andSITRANSProbeLU.Asaresult,echo-processingadjustmentsarenotgenerallyrequiredinmostapplications.

ThischapterpresentsSonicIntelligencefunctionalityandhowitrefinestheanalyticprocessdeterminingtrueechoandlevel.

TopicsEchoprocessingShotsandprofilesFiltersTimevaryingthreshold(TVT)EchoselectionFigureofmeritEchoprofilesEchoprocessingparametersNoise

Echoprocessing-intelligenceThepatentedecho-processingtechnologyembeddedinultrasoniclevelmeasurementproductsfromSiemensisknownasSonicIntelligence™2.SonicIntelligencedifferentiatesbetweentrueechoesfromthematerialbeingmeasuredandfalseechoesgeneratedbyobstructionsorelectricalnoise.Theresultisrepeatable,fast,andreliablemeasurement.

SonicIntelligenceisfield-proveninover1,000,000applicationsworldwide.

Thistechnologicaladvancementwasdevelopedinconsultationwithfieldserviceengineersandsupportedbyfielddatagainedfromdecadesofexperiencewithapplicationsinmanyindustriesandcontinuestoevolvetoday.Usinghigherordermathematicaltechniquesandalgorithmstoprovideintelligentprocessingofechoprofiles,this“knowledge-based”techniqueproducessuperiorperformanceandreliability.

SITRANSLUT400usesnextgenerationSonicIntelligenceforechoprocessing,providingadaptivedigitalfilteringofthetransducersignal.Forexample,whennoiselevelsarehigh,filtersareadjustedtomaximizethesignaltonoiseratio.ThisadvancedSonicIntelligencenotonlyallowsforbetterfiltering,butprovidesimprovedtrackingofechoes,andmoresophisticatedechopositioningalgorithms.

UnderstandingechoprocessingEchoprocessingisasimpleconceptandacomplexrealityastheinstrumentlooksateachgroupingofechoes(ashot)andprocessesthereturntodeterminethetrueecho.

Theshortshotusesanarrowtransmitpulsewhichreducestransducerringingtoprovideimprovedreliabilityforthedetectionofneartargets.Thelongshotusesawidetransmitpulsetoprovideastrongerreturnechotodetectmoredistanttargets.Bothshortandlongshotsareprocessed,andthenthebestisselectedwithabiasinfavoroftheshortshot.Onceanechoisselected,variousfiltersareappliedtostabilizethereading.

EventhoughSonicIntelligencewillselectthecorrectechoaftereverymeasurement,thereadingitselfmayfluctuateasaresultofchangingconditionswithinthebin.Averagingthereadingsreducesthefluctuationsbutcausesalaginresponsewhenthemateriallevelchanges.SonicIntelligenceusespowerfulstatisticaltechniques,togivestablereadingswhilestillallowingrapidresponsetoactualchangesinthemateriallevel.

ShotsandprofilesSolet’slookathowthesoftwarereadstheshotsandwhatitseesasthefollowingareimplemented:

filtersTimeVaryingThreshold(TVT)application

echoanalysis

TheechoprofileThecompleteprofileincludingtransmitandringdownisdisplayedandtheamountofblankingindexedinthesoftwareisshownonthebottomtrace.Theecholockwindow(orwindow)locksontotheselectedechoinordertoignorespuriousechoesfromagitatorbladesorrandomelectricalinterference.ATimeVaryingThreshold(TVT)curveprovidesareferenceforcomparingechoes.

SITRANSLUT400usesnextgenerationSonicIntelligenceforechoprocessing,providingadaptivedigitalfilteringofthetransducersignal.Forexample,ifnoiselevelsarehigh,filtersareadjustedtomaximizethesignaltonoiseratio.ThisadvancedSonicIntelligencenotonlyallowsforbetterfiltering,butprovidesimprovedtrackingofechoesandmoresophisticatedechopositioningalgorithms.

WhattheLUT400sees(or,moreaccurately,“hears”)fromatransmitpulseinanapplicationisstoredinadigitalformatandisreferredtoasan“echoprofile.”Thisprofileisadigitalrepresentationofthereturnedechoenergyversustime.

Findingthetrueecho

Astheechoesbouncebackfromthesurface,SonicIntelligencesoftwareparsestheinformationinitsgoaltofindthetrueecho.Theprocesscomprisesthreeactivecomponentsworkingtogetherintheselectionprocess:

1. Filters: enhancing the echoes and using Time Varying Threshold(TVT)toselect.

2. Trueecho:selection.

3. Selectedecho:verification.

One:FiltersFiltersarealgorithmprocessesinthesoftwarethattuneoutoutsideinterferencesandenhancetheechoesreturnedfromtheapplication.

ClippingfilterRemovesthehighspikesinthetimedomain,resultinginlessringinginthefilterandreducingtheimpactofhighnoiseontheprobabilityofpickingtherightecho.

DigitalbandpassfilterThismethodpermitsthedesignoftheoptimummatchedfilter,creatingthehighestprobabilityofselectingtherightechoovernoise.Eachtransducerhasabandpassfilterbasedonitstransmissionfrequency.

KalmanfilterThisalgorithmsmoothesandappliesdampingtoreadings,removingjitterandinstability.

TemperaturefilterAKalmanfilteralgorithmthatremovesjitterofthereportedtemperaturevaluecontributestoaccuratecalculationofthesoundvelocity.

SpikefilterElectricalnoiseproducesfalseechoeswhicharenarrowandhighcomparedtowiderechoesfromthematerialbeingmeasured.ThespikefilterinSonicIntelligenceusesthisdifferencetoidentifyandremove

electricalnoise.

Thespikefiltermeasuresthewidthofeachspikeandcutsoffanyspiketoonarrowtobeanecho.Theecholockwindowisthefirstlineofdefenseagainstrandomelectricalnoise,butthespikefiltereffectivelycorrectsforelectricalinterferencefrommachinerysuchasvariablefrequencydrives(VFDs).Thespikefilterwillneverremoveavalidecho.

NarrowechofilterManybinshavetargetsinthepathofthesoundwavethatproducefalseechoesthatcouldinterferewiththemeasurement.Thesemaybepipes,cables,orevenseamsinthebinwall.Inanarrowbin,itmaybeimpossibletomovethetransducerfarenoughawaytoavoidthesetargets.Thesetargetsproduceechoeswhichmakeitdifficulttoselectthecorrectechofromthematerialsurfaceinareliablemanner.

Insolids,theNarrowEchoFiltercanremoveundesiredechoesfromhardtargetssuchaspipes,beams,windows,orseams.That’sbecausetheseechoesarenarrowerthanthetrueechofromaninclinedsolidmaterialsurface.Inuse,thefilterisincreasedbysmallamountsuntiltheundesiredechoesareeliminated.Itisadvisabletomonitoroperationoveracompletefillandemptycycletoavoidsettingtoohighafiltervaluethatcouldwipeoutthetrueechoaswell.Thistechniquedoesnotapplytoliquidmeasurementwherethetrueechoisasnarrowastheundesiredecho.

ReformechoIndeepbins,thesoundwavefacesmanyobstaclesinitsjourneyfromtransducertomaterialsurfaceandbackagain.Theseobstaclesincludereflectionfromthebinwall,dust,aircurrents,changesinairdensity,andirregularitiesatthematerialsurface.Alltheseobstructionscombinetocreateafragmentedorsplinteredecho.Reformechobuildsthefragmentedechobackintoasingle,strong,well-definedechopulse.

Byincreasingreforminsmallamounts,theoperatorcanjointhepeaksofafragmentedechotoproducealarge,smoothecho.Usethisfeaturewithcautionbecauseifthereformistoolarge,thepeaksofunrelatedechoeswillbejoinedtogether.

EchoselectionalgorithmsAftertheechoprofilehasbeenenhanced,thefinaltaskisselectingthebestecho,ataskdeterminedbythebinconditions.

Two:Trueechoselection(selectionofechoreflectedbytheintendedtarget)ThisselectionoccurswhentheportionoftheechoprofileabovetheTimeVaryingThresholdmeetstheevaluationcriteriaofSonicIntelligence.Insignificantportionsoftheechoprofileoutsideofthemeasurementrange(e.g.FarRange)andbelowtheTVTcurveareautomaticallydisregarded.Theremainingportionsoftheechoprofileareevaluatedusingtheechoselectalgorithmandtheechoprofileportionprovidingthebestecho(confidence)isselected.

NOTE:Aconfidencevalueisastatictestofasinglesnapshotprofiletomaintainavalidreading;itrequiresthateachindividualprofilemaintainsitspeakabovethethreshold.Thewindowmaybelockedontheprofileforhoursorevendays,soiftheprofiledropsbelowtheTVTcurvejustonce,lossofechomayoccur.

TimeVaryingThreshold(TVT)Thetimevaryingthreshold(TVT)isusedasareferencetocompareechoesatdifferentpositionsintime.Afarechowillbeweakerbecausethesoundhastraveledagreaterdistance,butnearandfarechoesmust

becomparedinordertoselectthetrueecho.

Foragivenconditionofdust,temperature,orhumidity,theattenuationofsoundisusuallyuniformthroughoutthebin;therefore,theidealTVTisalinewithaslopeequaltotheattenuationofsoundindB/m.Thisslopeiscalculatedfromthedecliningportionoftheechoprofile.

TVTshaper(manualadjustment)TheshaperdividestheTVTcurveintoequalsegments,eachofwhichcanbeadjustedupordown.AnundesiredechocanbeignoredbyliftingtheTVTcurveatthepositionoftheecho.IftheTVTcurveisraisedtoomuch,however,thetrueechowillnotbedetectedwhenitisinthisregion.ItisnotnecessaryfortheTVTtocleartheundesiredecho,justcuttingitinhalfisusuallyenoughtode-emphasizetheundesiredecho.

TheadjustmentsrideupanddownwiththeTVTandmovehorizontallywhenthevelocitychanges.Allcalibrationpointsandrangesshouldbesetbeforeusingtheshaper.

Theshapercannotbeusedonechoesfromreflectionsofmaterialhang-upsbecausethefalseechopositionwillchangeifthematerialfallsoutofitshungupposition.

Autofalse-echosuppression(automaticTVTshaping)Thisfeatureautomaticallydetectsandsuppressesechoesfromvesselobstructions.PriortoactivatingtheAutoFalse-EchoSuppression,emptythetankasmuchaspossible.Ifthereisanagitator,itshouldbeoperating.DuringtheTVTLearnsession,thecontrollerfirespulsesandshapestheTVTaroundanyechofromanobstructionliketheagitator.ThisshapingiseasytoperformanddoesnotrequireaPC.

TheTVTwillthennotdroplowerthanthelearnedposition.

SITRANSLUT400hasadvancedtrackingabilityandcanfindtherealechoamongststationaryclutterechoes.Therefore,eveniftheechodropsbelowtheTVTcurve,itcanbeidentifiedwithnearcertaintyforapproximately30seconds.ThiscapabilityismeasuredbytheFigureofMerit(FoM)setting.

Therearefourselectionmethods:

measuretheareaofeachechomeasuretheheightofeachecho

measurethefirstmovingechoselectthefirstsignificantecho

FortheMultiRanger,LargestorFirstarethepreferredalgorithms.FortheAiRanger,togetherit’sALF.

ThesemethodscanbereferredtoasArea,Largest,andFirstalgorithms(ALF).AnothermethodusesTrackerwheretheuserselects/deselectsthealgorithmstandardsettings.SonicIntelligenceusesallfouralgorithmsoneachmeasurement.Foreachalgorithm,ascoreorconfidenceiscalculatedforeachechothatcrossestheTVTcurve,thenthescoresareaddeduptogiveatotalscoreforeachecho.Theechowiththehighesttotalscoreisdeemedtobethetrueechofromthematerialsurface.Thenetechoconfidenceistheconfidenceofthechosenechominustheconfidenceoftheechowiththenexthighestconfidencelevel;i.e.netconfidenceofthefirstchoiceisfirstchoiceminussecondchoice.

Occasionally,onealgorithmwillgivealowscoretothetrueechoandabetterscoretoafalseecho,buttheotheralgorithmswillpullthetotalscoreofthetrueechoup,andpushthetotalscoreofthefalseechodown.ThefinalselectedechoiscorrectbecauseSonicIntelligenceincorporatesadiversifiedportfolioofapplicationexperience.Foragivenbincondition,asinglealgorithmwillgivehigherechoconfidencebut,asbinconditionschange,anotheralgorithmmayberequired.Generally,usingallfouralgorithmsprovidesformorereliableoperationovertime.However,trainedoperatorscanadjustthedeviceparametersandfine-tunethealgorithmstosuittheirapplication.

SiemensMilltronicsequipmentalsocontainsanechoprocessingalgorithmcall“bLF,”alsoknownas“BestofLargestatFirst.”ThisalgorithmrunstheLargestalgorithmandFirstalgorithmandselectstheechowiththehighestconfidencevalue.ItdoesnotsumthevaluesasintheALFalgorithm.bLFisthebestchoiceforshortrangeliquidapplications.

AnotheralgorithmisTrueFirst(TF).ThisalgorithmselectsthefirstechothatcrossestheTVTcurve.Useinliquidsapplicationsfreeofobstructionswhenconfidenceoffirstechoishigh.

TheTR(TR)Trackeralgorithmselectstheechothatclosesttothetransducerandismoving.AnechothatisbelowtheTVTlineandmovingcanbedetectedbythisalgorithmandwhenitisnottrackinganecho,itbehavesthesameasbLF.

NOTE:OnlyuseTRalgorithminprocessapplicationswitheitherofthesetwoconditions:

continuouslevelchangesariskoffixedobstructionsthatcouldinterferewithtruelevelresultinginlowconfidence.

Three:SelectedechoverificationThisverificationisautomatic.Theposition(relationintimeaftertransmit)ofthenewechoiscomparedtothatofthepreviouslyacceptedecho.WhenthenewechoiswithintheEchoLockWindow,itisaccepted,updatingdisplays,outputs,andrelays.Ifthenewechoisoutsideofthewindow,itisnotaccepteduntilecholockrequirementsaresatisfied.

ThesethreeprocessesworkawayinthebackgroundastheSonicIntelligencesoftwaredeterminesthebestecho.However,theechoescanbefurthertunedshoulditbenecessary.

EchoqualityEchoqualityandconfidencecanbefurthertunedusingtheinformationprovidedbythedevicefromthefollowingfeatures.

Figureofmerit

FigureofMerit(FOM)measuresthequalityofthereportedprocessvalue:highervaluesrepresentbetterquality.Evenwhenalowconfidencevalueexists,ahighFOMwillensurethetrueechohasbeenselected.Approximately20readingsareusedtosupporttheFOMvalue.

EXAMPLEFOMgreaterthan75%=goodqualityFOMlessthan50%=poorqualityContributionstotheFoM:

successofthetracking(howcloselycanthenextlevelversustheactualnextlevelbepredicted)levelofnoiseconfidenceofthelastechotimeintervalsincelastvalidechospeedatwhichtheprocessismovingqualityoftheechoshapeandhowithelpsthecalculationoftheechoposition

NOTE:IfFoMislow,reducethenoiseintheprocess,orchecktheinstallationtoincreasesignalquality.

EchoparameterfinetuningSonicIntelligencesoftwareeliminatestheneedforecho-processingadjustmentsinallbutthemostdifficultapplications(lessthan1%).Iffinetuningisrequired,operatorscanusethemoreadvancedadjustmentparametersavailableinSiemenstransceivers.

Onlyoneortwoecho-tuningparametersshouldbeadjustedatatime,sothattheimpactofeachadjustmentcanbecarefullymonitoredforacompletefillandemptycycle.Adjustmentsmadetoreachaconfidencefigureatacertainbinlevelmaynotholdunderchangingbinlevels.Donotrelysolelyontheconfidencefigure,butlookattheechoprofileanddecideiftheechoiswelldefinedundervariousconditionsandwillprovidereliabletrackingoflevelsfromemptytofull.Thisisespeciallyimportantduringaimingandmounting.

EchoprofilesTheechoprofile,agraphicrepresentationofthereflectedechoreceivedbythetransducer,isanimportantdiagnostictool.Digitallygenerated,theprofileisstoredbythetransceiverandcanbeviewedusingseveraltypesofconfigurationsoftware,includingSIMATICPDM(ProcessDeviceManager),AMS,FDTs,DolphinPlus,andSuperSonex.

Theechostartsoutasananalogsignal:

Thissignalisdigitizedbythetransceiver’sA/Dconverterandchangedintoanechoprofile,whichisameasurementoftheechoenergyversustime.

Toreadtheprofile,startattheleftside,whichrepresentsthetanktop,andmoveacross.Thefartherright,thefartherdownintothetanktheshotgoes,readingthedistance.Theupwardspikesindicateechoesandthestrengthindecibels.

ProfilecomponentsThereareseveralcomponentstoanechoprofile,eachrevealingasignificantaspectoftheecho.Theechoprofilecomponentsareshowninthefollowingdiagrams:

Echoprofile

Ringdown

Theleadingedgeoftheechoprofileisthedecayofthetransmitpulse,alsoknownasthe“transducerringdown.”Thisistheportionoftheechoprofileshowingthegradualrecoveryofthecrystalafterashothasbeentaken.

TVTcurve(TimeVaryingThreshold)

TheTVTcurveisadigitallygeneratedthresholdlevelthatactsasavalidationpointforthereceivedechoes.Itisadynamicthresholdlevel;anypartoftheprofileabovethecurvewillbeincludedintheechovalidationprocess.

Echomarker

Theechomarkerrepresentswhatthecontrollerhasprocessedasthecorrectecho(ormateriallevel)forthatparticularechoprofile.Itmayormaynotpresentthisasthelevelreading.TheEchoLockWindowcontrolsthelevelreadingoutput.Theheightofthemarkerrepresentstheechoconfidence;thelargertheheight,thebettertheconfidencethatthisistheechothatmostrepresentsthetruelevelforthisparticularprofile.

Echolockwindow

TheEchoLockWindow(orsimplytheWindow)controlshowfarthelevelcanchangebetweenshots.Fromshottoshot,thelevelchangecannotexceedthewidthoftheecholockwindow.Iftheechomarkerfallswithinthewidthofthewindow,thecontrollerwilloutputthelevelasindicatedbytheechomarkerandre-centerthewindowontheecho.Iftheechomarkerfallsoutsidethewindow(e.g.marksanechofromabladeofanagitator),thenthecontrollerwillignorethemarkedechoandoutputalevelrepresentedbythewindow(whichalsorepresentsthelastvalidreading).

Thewidthofthewindowissetbythemeasurementresponse(ordamping)parameter.Iftheapplicationlevelchangesrapidly(aprocessvessel),programafastmeasurementresponseandthewindowwidthwillbequitewide.Iftheapplicationhasaslowmovinglevel(astoragevessel),thensetthemeasurementresponseparametertoslowandthewindowwidthwillbequitenarrow.

Ifthereisasuddenchangeinlevelandtheechomarker(thistimerepresentingthetruelevelandnotafalseechofromanagitatorblade)isoutsidethewidthofthewindow,thecontrollermaintainstheleveloutput

atthelevelrepresentedbythewindow,thelastvalidreading.Italsobeginstowidenthewindowatthemeasurementresponserate.Iftheechomarkerpointsatthesameechooutsidethewindowforfiveshotsinarow,thecontrolleracceptsthatthisisnowtruelevelandchangestheleveloutput(thedisplay,mAoutput,ordigitaloutput)atthemeasurementresponserateinthedirectionofthetruelevel.Thewindowcontinuestowidenatthemeasurementresponserateandoncethetrueechoiswithinthewindowwidth,thewindowwillshrinkbacktoitsnormalsizeandre-centeritselfonthetrueecho.

Echoprocessingparameters

Thevaluesofsomeoftheadvancedechoprocessingparametersareplacedontheechoprofileasaconvenienceandcanbeusedasareferencewhensubsequentlyviewingtheprofiles.

Includedarethevaluesforthefollowing:

echoalgorithmspikefilter

narrowechofilterechoreformTVTtypeconfidencethresholdshortshotrangeshortshotbiaswindowsillpercentagenearTVTdB

Echoconfidence

Echoconfidencerepresentsthecertainty,orconfidence,thatthechosenechoisthecorrectecho.ThevalueisgeneratedfromoneoftheechoprocessingalgorithmslikeALForbLF(seeSonicIntelligence).Confidenceisshownintwoareas:attheselectedechoandbesidetheechomarker.Thevaluesbesidetheechoshowtheconfidencevaluesgeneratedbyindividualalgorithms.IntheaboveprofileitshowsL:20and

F:20–meaningthattheLargestalgorithmandtheFirstalgorithmeachgeneratedaconfidencevalueof20.Theconfidencevaluebesidetheechomarkerisshownas:

Thisindicatestheshortshotconfidenceis0,thenetlongshotconfidenceis20,andthebracketsaroundthe20indicatethatthelongshotwasusedtoprocessandoutputthelevelmeasurementreading.

Theecho

Thisgraphshowsanecho,withspikesthataresharporgradual(dependingonthematerial)risingintheechoprofile.Sharpechoesarisefromflatmaterialsurfaceslikeliquids,asintheaboveprofile.Gradual,widerechoescomefromsolidmaterial;clinker,coal,orgrains,aremoregradualintheirrise,andoftenlookliketheechobelowfromplasticpellets:

EchostrengthThestrengthoftheselectedechoindBabove1microvoltRMSiscalculatedasechostrength.

Theechoprofilesareaninvaluableassetwhentroubleshooting,andatechniciancandeterminethefollowingfromtheprofilebasedontheechoes:

goodechostrengthandlowconfidencemeansmultipleechoestogetthelevelreadinglowechostrengthandlowconfidencecanmeantheechoisweak,theresultofpooraiming,orhighattenuationfromdust,steam,orC02.Thesurfacemayalsobefoamyorpoorlyreflectivefromextremeturbulence.

NoiseNoiseinanultrasonicsystemcanalsobegeneratedbyelectricalinterferencereceivedfromthetransducercables.Thisinterfereswiththeechoreadingandentersthecontrollerfrommanysources:

mainpowermAoutputexternaltemperaturesensor(ifused)radiatedfromnearbyelectricaldevices

Theelectricalnoiseispickedupontheprofile.Thetwolinesatthebottomleftrepresentthenoiseparameter.ThetopoftheboldverticallineisthepeaknoiseindB;thesmallhorizontallineindicatestheaveragenoise.Inthisexample,thepeaknoiseis5dBandtheaveragenoiseis-3dB.

Thebestmethodforensuringthelowestnoisepossibleistousetherecommendedtransducercable.ThenewerSiemensMilltronicscontrollers(SITRANSLUT400,MultiRanger100/200,HydroRanger200)useshieldedtwistedpaircablewhileestablishedmodels(SITRANSLU)

useRG62A/Ucoaxialcable.Theshieldsmustbeproperlyconnected,andusegroundedmetalconduittoshieldthecablefromelectricalnoiseandtophysicallyprotectthecablefromdamage.

Ingeneral,averagenoiselevelsabove30dBarecauseforconcernandnoiseshouldbereduced.

ThelevelsofnoisepresentatthereceiverinputcanbeviewedonthedeviceLocalUserInterfaceastheaveragenoiseandthepeaknoise.Ingeneral,themostusefulvalueistheaveragenoisebecausethepeaknoiseisaspikethatcanbefilteredout.Averagenoise,however,istheoverallbaselinenoise.Iftheechostrengthdoesnotexceedthebaselinenoise,therewillbeproblemsdiscerningtheechofromtheambientnoise.

AdaptiveprofileblendingWhennotinahighnoiseapplication,theLUT400processeseveryshotindividually.Ifnoiselevelsincreaseaboveathresholdof35dB,theSITRANSLUT400blendsmultipleprofilestogether,increasingthereliabilityofechoselectionandpositiondetection.Thisreplacesthepreviousprocessofaveraginganumberofshotsandrespondsmorequicklytofastchangingmateriallevels.

NoiseinterferenceWithnotransducerattached,thenoiseisunder5dB,whichiscalledthenoisefloor.Ifthevaluewithatransducerattachedisgreaterthan5dB,thensignalprocessingproblemscanoccurbecausethegreaterthenoise,thelessthedistancethatcanbemeasured.Anyaveragenoiselevelgreaterthan30dBisgenerallycauseforconcernunlessthedistanceismuchshorterthanthemaximumspecifiedforthetransduceranditpowersitswaythroughthenoise.

Determiningthenoisesource

Noisecanbefromeitherelectricalinterferenceorfromanacousticobstructionthatintervenesanddistortstheintendedecho.Thus,thefirststepistodeterminethenoisesource.

Startbydisconnectingthetransducerfromthetransceiver.Ifthemeasurednoiseisabove5dB,gotoNon-transducernoisesourcesbelow.Fornoiselevelsbelow5dB,proceedwiththefollowing:

1. Connectonlytheshieldwireofthetransducertothecontroller.Ifthemeasured noise is below 5 dB, continuewith the next step. If thenoiseisabove5dB,gotoCommonwiringproblems.

2. Connect the white and black transducer wires to the controller.Recordtheaveragenoise.

3. Remove the positive wire of the transducer. Record the averagenoise.

4. Reconnect thepositivewireand remove thenegativewire.Recordtheaveragenoise.

UsetheNoiseModificationtabletodeterminetheappropriatenextstep.Thetermshigher,lower,andunchangedrefertothenoiserecordedintheprevioussteps.

Noisemodificationtable

noise -removed +removed Goto:

higher higher

unchanged

Reducingelectricalnoise

Commonwiringproblems

Reducingacousticnoise

unchanged higher

unchanged

Reducingelectricalnoise

ContactSiemens

lower higher

unchanged

Commonwiringproblems

Non-transducernoisesourcesRemoveallinputandoutputcablesfromthecontrollerindividuallywhilemonitoringthenoise.Ifremovingacablereducesthenoise,thatcablemaybepickingupnoisefromadjacentelectricalequipment.Althoughcontrollersaredesignedtoworknearheavyindustrialequipmentsuchasvariablespeeddrives,donotlocatethemnearhighvoltagewiresorswitchgear.

Becauseofhighcosts,filteringcablesarenotrecommendedunlessallotheroptionshavebeenexhausted.

Ensurethatlowvoltagecablesarenotbeingrunadjacenttohighvoltagecablesorneartoelectricalnoisegeneratorssuchasvariablespeeddrives.

Movingtheelectronicsafewmetersawayfromthesourceofnoisewillfixtheproblem.Shieldingtheelectronicsisanotheroption,albeitexpensiveanddifficulttoinstallproperly;theshieldingboxmustenclosethecontrollerelectronicscompletely,andallwiresmustbebroughttotheboxthroughgroundedmetalconduit.

CommonwiringproblemsTheinstallationwiringcanalsopresentnoiseproblems.

makesurethatthetransducershieldwireisconnectedattheelectronicsendonly.Donotgrounditatanyotherlocation.donotconnectthetransducershieldwiretothewhitewire.(AppliesonlytotheSITRANSLUT400,MultiRanger100/200,HydroRanger200,andSITRANSLUC500)theexposedtransducershieldwiremustbeasshortaspossible.connectionsbetweenthewiresuppliedwiththetransducer,andanycustomerinstalledextensionwireshouldbedoneingroundedmetaljunctionboxes.

ForSITRANSLUT400,LUC500,MultiRanger100/200,andHydro-Ranger200,thetransducerextensionwiremustbeshieldedtwistedpair.ForSITRANSLUseries,AiRangerseries,HydroRangerPlus,andMiniRangerPlus,useRG-62A/Uco-axialcablefornoisereductionpurposes.Seetheinstallationsectionofthecontrollermanualforcorrectcablespecifications.

NOTE:OnSiemenstransducers,thewhitewireisnegativeandtheblackwireispositive.Iftheextensionwireiscoloreddifferently,makesurethatitiswiredconsistently.

Reducingelectricalnoiseensurethatthetransducercabledoesnotrunparalleltoothercablescarryinghighvoltageorcurrentmovethetransducercableawayfromnoisegeneratorssuchasvariablespeeddrivesputthetransducercableingroundedmetalconduitfilterthenoisesource

AcousticnoiseToconfirmthattheproblemisacoustical,placeseverallayersofcardboardoverthefaceofthetransducer.Ifthenoiseisreduced,thenoiseisdefinitelyacoustical.

Reducingacousticnoisemovethetransducerawayfromthenoisesourceuseastillingwellinstallarubberorfoambushingorgasketbetweenthetransducerandthemountingsurfacerelocateorinsulatethenoisesourcechangethefrequencyofthenoise.Thecontrollerisonlysensitivetonoisebetween25KHzand65KHz

SummarySonicintelligencebeatsattheheartofSiemensultrasonictechnology.Derivedfromthecumulativeexperienceofoveramillionultrasonicapplications,thissophisticatedechoprocessingfocusesalasersharpeyeonthetruelevelintheapplication.

1Drucker,Peter.1909-2005.2™SonicIntelligenceisatrademarkofSiemensMilltronicsProcessInstruments.

ChapterFive

InstallationThereisjoyinrepetition,

thereisjoyinrepetition,thereisjoyinrepetition.1

Ultrasoniclevelmeasurementinstrumentationoffersnon-contactingtechnologythatisvirtuallymaintenancefreeandcosteffectiveinmanyapplications,fromthewaterandwastewaterindustriestosolidsandliquidsmeasurementinavarietyofindustrialsettings.

Ultrasonicsystemsuseatransducertosendelectronicpulsestoacontrollerwhichinterpretsthemanddeterminesleveldistance.IntegratedsystemsliketheSITRANSProbeLUhousethetransducerandcontrollertogetherandcanalsofunctionastransmitterswithinanetwork,usingthelatestincommunicationhardwareandsoftwaretotransmitdatabacktoitssourceforimmediateprocessing.Theycanoperatepumpsandalarmsdirectlyorsenddatathroughcommunicationsystems.

Othersystemsseparatethetransducerfromthecontroller,andonlythetransducerisactuallyattheapplication.Thecontrollercanbeasfaras365meters(1200ft)away.Theapplicationcanbeconfiguredandmanagedfromadistance;thusindangerousorawkwardsituations,nooneneedstoreturntothesiteaftertheinitialinstallation.

Ultrasonictransducersareveryeasytoinstallandmaintain,ensuringmanyyearsofreliableoperation.Thischapterdiscussesinstallationrequirementsandbestpracticestomaximizethebenefitsofanultrasonicapplication.

Topicstransducerselectionlocationandobstructionsvesselstanksandaccessnozzles,standpipes,stillpipescablingopenvessels,flumes,weirsliftstationspositioncontrolapprovals

InstallationconditionsarethesameforthetransducersensorsonlyorfortransmittersliketheSITRANSProbeLU.Thecontrollersaregenerallymountedawayfromtheapplicationswheretheycanbeconfiguredin

comfortandsafety.

SelecttherighttransducerTheEchomaxXRS-5isapopulartransducerchoice.Withameasurementrangeof0.3meters(oneft)toeightmeters(26ft)onliquidsandslurries,itissuitableformostshorttomid-rangeapplicationsinthewaterandwastewaterindustries.

Forshort-rangesolidsapplications,theEchomaxXPS-10providesahighpoweroutputsuitablefordustyapplications.

Forapplicationsbeyondeightmeters(26ft)andupto15meters(50ft),EchomaxXPS-15transduceroffersthemostaccurateperformanceforsolids,liquids,andslurryapplications.

Applicationsbeyond15meters(50ft)requiretheXPS-30orXPS-40transducerswithlowerfrequenciesandmorepowerfuloutput.

Manyconditionscanaffecttheperformanceofyourultrasonicsystem,andtheyneedtobenotedwhenchoosingatransducer.Theapplicationenvironmentalsoinfluencestheperformance,andinthischapterwediscusstheactualinstallationcriteriaforthetransducersafteryouhavedecidedwhichtransducerisappropriateforyourapplicationandiscompatiblewiththecontroller.

LocationTheactualphysicallocationofthetransducerisveryimportantforoptimalperformance,andthereareanumberoffactorsthatmustbeconsidereddependingontheapplicationtype.Thusthetransducermountingformeasuringopenchannelflowisdifferentfrommeasuring

liquidsinavesselanddifferentagainfrommeasuringsolids.However,regardlessoftheapplicationtype,theonecommonconditiontoavoidinanyapplicationistheobstruction.

Keepobjectsoutoftheultrasonicconetoreducefalseechoes.

ObstructionsObstructionsarethemostimportantapplicationelementstobeawareofastheyblockthesoundsignalpath.Typicalvesselobstructionsincludeladders,pumps,braces,lights,agitators,walkways,andloadingchutes.Ifobstructionsareunavoidable,choosethelocationwheretherearetheleastnumberofobstructions.Thetransducermustbeableto“see”thematerialbeingmeasured,andabeam,pipe,orstructuralbracewillblocktheviewandaffectthereading.Obviously,theclearertheaccesstothematerial,thebettertheperformance.

Becausetheultrasonicpulseradiatesinaconeshapefromthefaceofthetransducer,keepingobjectsoutsideofthissignalconereducesthechanceoffalseechoesbeingrecorded.Thetransducerbeamanglespecifiesthedegreeofthecone(seeillustrationbelow)wheretheultrasonicpulse’spowerislowerbythreedB(decibels).

ClosedvesselsInclosedvessels,locatethetransduceronastandpipeorstillpipe,oranyaccessportornozzlethatoffersanunobstructedviewofthesurfacetobemonitored.Thestandpipeorstillpipecannegatetheblankingrequirementsbydistancingthetransducerfromthematerial.

TanksThevarietyofvesselsmeasuredbyultrasonicsisextensive,fromsmallonemeterhigh(3.3ft)plasticcontainersofwoodglueresinstothreemeterhigh(10ft)stainlesssteeltanksfulloficecreambaseto60meter(200ft)concretegrainsilos.Ultrasonicmeasurementhasveryfewlimitationswhenitcomestovesselsizeorgeometry;itsimplyneedsaclearpathforthesoundtotraveltothematerialbeingmeasured.Theshapeofthetankmatterslittle.

Althoughtankorvesselsizescanvary,themajorityarevariationsononlyafewstandardshapes.Transducerlocationcanchangeslightlydependingupontheshapeofthevessel.

Theseshapesinclude:

FlatbottomtanksCommonapplicationsincludewastewaterwetwells.Locatethetransducerasclosetothecenteraspossibleandawayfromobstructionsinthebeampath.Ifmountinginthecenterisnotpossible,maintaina10:1ratiowhenmountingclosetothesideofthevessel.

NOTE:Foreverytenmetersverticalmeasurement,locatethetransduceronemeterfromthesidetopreventanyinterferingechoes.

Conebottom/parabolicbottomtanksFortanksusedinliquidmaterialapplications,mountthetransducerinthecentersothatmeasurementtothebottomoftheconeispossible.Ifthisisnotpossible,programthecontrollersothatthebottomofthetankisthetopofthecone.

Ifthematerialisasolid(i.e.grain),thenatransducerwithanaimingdeviceshouldbeusedandthetransduceraimedtowardsthebottomoftheconetoensuremeasurementintothedrawpoint.

HorizontaltanksMountthetransducerasclosetothetopcenterofthevesselaspossibletomakeuseofalltheavailablespan.

NOTE:Echoprocessingsoftwarecanignorereflectionsfromsupportbeams,weldbeads,ladder,ormaterialbuildupalongthevesselsides.

TankaccessTherearemanywaystoaccessasealedtankorvessel:

cutholeand/orEasyAimernozzlesstandpipesstillpipessidepipes

Cuthole/EasyAimer:sometanksorvesselshavenoentryroutes,butcanbeaccessedbycuttingaholeorusinganexistingtrapdoortomountthattransducer.TheSiemensMilltronicsEasyAimerassistsinaimingthetransducerthroughanaccessportintothevesselatananglerequiredtogettheaccuratereading.Attachthetransducertotheaimingkitusingthecouplingprovidedwiththekitandthenaimpastthetransducersothatthesoundpathisperpendiculartothematerialsurface.

NOTE:Besuretolocatetheaccessportsothatnoobstructionsareinthebeampath.

TheEasyAimeraimsthetransducertothelowleveldrawpoint.Thetransducercanberevolvedthrough360°andangledat0to27°offvertical.Itcanwithstand100kPa(onebaror15psigauge)pressurewithaggressiveenvironments.

Nozzles:aprotrudingaccesspipelocatedonthesurfaceofthevessel.Ashortoutlet,orinlet,pipeprojectingfromtheendorsideofahollowvessel.

Standpipe:anaccesspipethatprotrudesthroughavesselwallandispresentonboththeoutsideandtheinsideofthetank,andmaybeusedasamountingplatform.

Beawareofthefollowingwhenusinganozzleorstandpipe.Whenmountingflangedtransducerstoclosedtopvessels:

besurenobuildupformsinsidethestandpipe(maycreatefalsereadings)eliminateweldsandseamsastheyhavethesameeffectasbuildupheightshouldbelessthanthreemultiplesofthediameter(H<3D)minimumdiameteris76millimeters(3")ifheightislessthan150millimeters(6"),factoryblankingcanbeused.Ifheightisgreaterthan150millimeters,increaseblankingto150millimetersbeyondthebottomofstandpipe,orextendstandpipeintotankandcuttheendata45°angle.

StandpipeinstallationCuttheendofthestandpipeona45°angleandremoveanyburrsfromcutting.Thisanglewillhelpmatchtheimpedanceoftheairinsidethepipewiththerestoftheapplicationenvironment.A90°cutcouldcreate

aninterferingechoattheendofthestandpipeandreducetheconfidencevalueoftherealecho.

Forstandpipeinstallations,useafactorybondedflangedtransducerorsplitflangekitthatwillreadilymatetotheflangedstandpipe.Anotheroptionistohangthetransducerfromablindflange.

Thestandpipeshouldbeasshort,andthediameteraslarge,aspossible.The-3dBconeofthesoundbeamshouldnotintersectthestandpipewallinapplicationsopeningintoavesselorlargerarea.Otherwise,additionalblankingwillberequiredtocompensatefortheinterferencezonecreatedbytheopening.

Stillpipes/StillingtubesAstillpipe(essentiallyanextendedstandpipe)maybeusedforturbulentliquidapplicationsasitextendsfurtherdownintothevessel,andisalsohelpfulinfoamyconditionsbyisolatingthesurface.

Astillpipeissimplyasmoothwalledpipethatextendsfromthetopofthevesseltothebottom.Thelowerendofthepipeisopentoallowthecleanfreeflowingliquidtomoveupthepipe.Inanapplicationwherethevesselisemptiedcompletely,itmaybepossibleforthefoamtoenterthebottomofthestillpipe.Inthiscase,aJ-tubeisrecommended.TheJ-tubeisastillpipewithan180°elbowatthebottom.Whenthevesselisemptiedtherewillalwaysbeasmallamountofliquidintheelbow,anditwillnotallowanyofthefoamtopassintothestillpipe.

Thesameconsiderationsforastandpipeshouldbeappliedtostillpipe:

donotperforateordrillholesalongthelengthofthestillingwellweldsandcouplingscanaffectthereliabilityoflevelmeasurementavoidbuilduporotherdebrisontheinsideofthewellwallensurethereisaventholeatthetopofthestillingwell

SidepipesSidepipesaresimilartostillpipesbutareontheoutsideofthevesselandiscomparabletoasightglass.Thelevelisreflectedinthejoinedpipe.Sidepipeseliminatefalseechoesfromobstructionsandfillstreams,and

areoftenusedinsumpsandwells.Thefollowingmustbenoted:

pipesshouldbeseamlesswithaminimum150millimeter(6")diameterpipeshouldbeventedatthetoppipemustbekeptcleanofbuildup

FlangesTransducerscanbemountedwithavarietyofflanges:

bondedflangesfornon-corrosiveapplicationsPTFE–facedflangesforcorrosiveapplicationssplitflangesforfieldretrofitformountingonaflangedstandpipe

Overtighteningthemountinghardwarecanleadtotransducerringing.

Tightentheflangeboltsevenlytoensureagoodsealbetweenthematingflanges,butdonotovertighten.Thiscanadverselyaffectperformance.Handtighteningshouldbesufficient.

LiquidapplicationsForbestresultsinliquidlevelmeasurement,thetransducermustbeperpendiculartothematerialsurface.Whetheritisthroughastandpipe,nozzle,orpositionedinthevesselusinganexistingopeningoranewlycutone.

Solidsapplications

Notethefollowingwheninstallingthetransduceronatank:

Inmosttanks,thetransducershouldbecenteredasmuchaspossible(withoutinterferencefrominlet)foroptimumreadingrange.Whetherthetankisemptyorfull,itmustcontainitsnormalvaporconditions.Whetherthetankisemptyorfull,itshouldbeatitsnormaltemperature.Thetransducershouldbeperpendiculartotheangleofreposeofthematerial,whichusuallymeansmountingittoonesideandatanangle.

Inconebottomtanks,aimthetransduceratthedrawpointatthecenterofthecone.Aimthetransducerawayfromseams,structuresandirregularitiesinthebinwall.Locatethetransducerawayfromthematerialinflow.Onfluid-likesolids,aimthetransducerperpendiculartothematerialsurface.Ondualdischargebins,aimthetransduceratthedrawordischargepointtoensureaccuratereadingsonemptying.UseEasyAimer.Keeptransducerawayfromfillpoints,asthematerialenteringthevesselcouldreflectthesoundpulseandgiveanincorrectlevelreading.Lookoutforratholingwherethedischargehascreatedadrainholethatcangiveincorrectlevelreadings.Bridging,wherethedischargedmaterialdoesnotshow,alsoleadstoincorrectlevelreadings.

ProtectionForsolidsapplicationswherethetransducercancomeincontactwithmaterial,suchasinarockboxorcrusher,protectthetransducerfromflyingrocksbysurroundingitwithawirecage.Securetheinstallationby

connectingasafetychainfromthetransducertothemountingsurface.

UsepropercablingCableselectionisaveryimportanttoensureproperfunctioningofthetransducer.Allwiring,conduit,andjunctionboxesaretobeinstalledaccordingtoalllocallaws,rules,andregulationsand/orinsurancecompanyrequirements.Refertoproductmanualsforwiretypeandconnectionsforspecifictransducermodels.

Installametaljunctionboxandtwoconductorterminalstripsataneasilyaccessiblelocation.Terminatecablesperthetransducerinstallationmanual.Ensurethatthecableshieldsareisolatedfromtheground.Failuretoproperlyinsulatethetransducershieldcancauseashorttotheground.

Groundedmetalconduitisrequiredbetweenthetransducerandthemetaljunctionbox.Groundedflexconduitisacceptable.Rigidmetalconduitshouldbeinstalledfromthejunctionboxtotheelectronicspackage.InthecaseofmultiplepointsystemsliketheSITRANSLU10,asingleconduitcanbeusedforalltransducercables.Iftransducercablesruninthesameconduitorincloseproximitytoeachother,besuretosynchronizethetransceivers(seedeviceinstructionmanual)topreventcrossinterference.

Transducersallhaveintegralcableswith“pigtail”leadsattheend.Thelengthofintegralcablecanbeselectedwhenorderingandareavailableinlengthsofupto100meters(328ft);however,thefivemeter(16.5ft)andtenmeter(32ft)lengthsaremostpopular.

Thepigtailendscanbedirectlyconnectedtothecontroller’sterminalblocks,orthecablecanbeextendedusingafield-mountedjunctionboxandadditionalcable,uptoatotallengthof365meters(1200ft).Theadditionalcabletypedependsonthecontroller,notthetransducer.Forextendedrunsbeyondthetransducer’sintegralcablealwayschecktheproductmanualforrecommendedcabletype.Somecontrollers,likethe

SITRANSLUT400andMultiRanger200,use18AWGshielded,twistedpaircable;othermodels,liketheSITRANSLU10,useRG62Ucoaxcabletoextendthelengthofthetransducercable.

Alltransducercableshouldbemountedingroundedmetalconduittoprovidethebestelectromagneticnoiseshieldingandphysicalprotectionofthecableitself.Donotruncablesnearhighvoltageorcurrentruns,contractors,orSCRcontroldrives.

DiagnosticsoftwareFordifficultinstallationsinvolvingexcessivedust,turbulence,obstructions,orverynarrowwells,diagnosticsoftwareisavailabletohelpfine-tunethetransducer’saimandtosetparameters.SiemensMilltronicsusesSIMATICPDMforviewingechoprofilesandtodiagnoseechoproperties.SupportforDTMsandothertypesofconfigurationsoftwareisavailableforsomemodels.

MatchenvironmenttemperatureIfatransducerbecomessignificantlywarmerorcoolerthantheaverageairtemperatureintheapplicationenvironment,itmayaffectaccuracybecausethespeedofsoundchangeswithtemperature.Althoughsome

transducershavebuilt-intemperaturecompensationfeatures,it’salwaysbesttomountatransducerwhereitwillsharethesameairtemperatureastherestoftheapplicationenvironment.

Fortransducersmountedoutdoorsindirectsunlight,provideasunshield.Ifthereisasignificanttemperaturedifferencebetweenthemediumandthesensorsurface,connectanexternaltemperaturesensortothecontrollerforincreasedaccuracy.

OpenvesselsLocatethetransducerascloseaspossibletothemaximumheightofthematerialbeingmeasuredwithoutinfringingontheblankingdistance.Theblankingdistancevariesamongmodels,sochecktheproductmanualforblankingdistanceinstructionsrelatedtoyourtransducer.

MountingbracketsTheseversatilebracketsprovidesturdyplatformsforopenvesselsandforopenchannelmonitoring.Manufacturedfrom304stainlesssteel(1.4301),thesebracketscomeinavarietyofshapestofitanyapplication.

Openchannelmeters:weirsandflumesOpenchannelflowoccurswhenliquidflowsinachannelwithafreesurfaceopentoatmospheresuchasstreams,rivers,irrigationcanals,andditches.Non-pressurizedpartiallyfilledpipes,includingstormsewers,sanitarysewers,andculvertsalsoqualify.Openchannelflowconditionsarecommonlyfoundinwastewatertreatmentsystems,industrialwastesystems,andirrigationsystems.

Inanopenchannel,pressureisnottransmittedfromoneendtotheotherendofthefluidlikethatinafullyflowingpipe,andonlytheforceofgravityonthefluidcausestheopenchannelflow.

Oneofthetime-provenandcommonmethodsofmeasuringflowusesaprimarydevicetorestricttheflowofliquidsothatamathematicalrelationshipexistsbetweentheliquiddepth(headlevel)andtheflowrateorvelocityofthewater.

Therearetwotypesofprimarydevices:weirsandflumes.

WeirsWeirsarethemostcommontypeofprimarydevicesusedtomeasureopenchannelflow.Aweirisadambuiltacrossachannelandtheliquidflowsoverit,oftenthereisacutoutornotch,andtheweirisgenerallynamedfortheshapeofthenotch.Aweiristhesimplestandoldesttypeofchannelflowmeasuringdevice.

Amathematicalrelationshipcanbederivedtocalculatethedischargethroughthesharp-crestedweirs.

FlumesAflumeisaventuridevice2placedwithinachanneltorestricttheflowandproduceahead(level)/flowraterelationship.TheflowinducedisbetweencriticalandsupercriticalflowlevelssoonlyoneheadmeasurementisrequiredtomeasureflowQ.

Mostflumesaredesignedtopasstheflowsthroughacriticalstateforaspecifiedheadrange,providedflumesareinstalled,maintained,andoperatedwithinthespecifiedrange.

Commonflumesinclude:

ParshallflumeRectangularflumePalmer-Bowlusflume

Ultrasoniclevelmeasurementdevicesareideallysuitedtomeasuringwaterlevelinprimarydevices.Thenon-contactingnatureofultrasonicsallowsformeasurementwithoutdisruptingtheflow;contactdevicesusedformeasuringheadlevelwouldactuallydisruptthelaminarflowandaffectthehead/flowrelationshipandtheoverallaccuracyoftheflowmeasurement.Thesurfaceofthewaterissmooth(ideallythereisnoturbulence)andthisprovidesaperfectreflectingsurfaceforsoundwaves.Ultrasonicdevicescanalsoprovideintegrationoftheinstantaneousflowratetoatotalizedamount.

Theoverallaccuracyofopenchannelflowmeasurementisdependentonthefollowing:

theprimaryelementselectionanddesignproperinstallationoftheprimarydevicetheeffectoftheapproachflowtheeffectsofthedischargeflowtheliquidbeingmeasuredthesecondarymeasuringdevicefieldcalibrationoftheprimaryelement(provingthatitdoesperformasintended)fieldcalibrationofthesecondarydevice

Thissectionfocusesonthesecondarydevice,theultrasonicopenchannelmeter,andthefield-mountedtransducer.Manytextsandguidelinesareavailablethatfocusontheprimarydeviceanditsinstallationcriteria;pleaserefertotheseforselectingandinstallingaflumeorweirproperly(seeISCOHandbook)orwww.usbr.gov/pmts/hydraulics_lab/pubs/wmm/cover.html

Theprimaryrequirementforaccuratemeasurementisthattheapproachingflowintoaflumeoroveraweirmustbetranquilandnon-turbulent.Thisisperhapsthemostimportantcriteriawheninstallingaprimarydeviceandalsohasaneffectontheaccuracyofthesecondarydevice.Iftheflowisturbulentintheapproachchannelthenthelevelwillnotbestable,causingdifficultiesforthesecondarydevicetolockontoalevelthatisrepresentativeoftheactualflowrate.

TransducerlocationThelocationofthetransducer,eveniftheflowissmoothandtranquil,isimportantiftheheadversusflowrelationshipistobemaintained.Forstandardweirs,thetransducershouldbelocatedupstreamminimumthreetimesthemaximumheadlevelasshownbelow:

BS-3680V-notchweirISO1438/1(BS-3680)thinplateV-notchweirrequiresthatthetransducerbelocatedfourtofivetimesthemaximumheadlevelbackfromtheweirplate:

ParshallflumesForflumes,thelocationofthetransducerdependsupontheflumetype.CommoninNorthAmerica,Parshallflumeshavetheheadmeasuredat2/3thelengthoftheconvergingsectionfromthebeginningofthethroatsection:

BS-3680/ISO4359rectangularflumeAnISO4359(BS-3680)rectangularflumeheadlevelmeasuresfourtofivetimesthemaximumheadlevelupstreamasshowninthefollowingdiagram:

PipelineflumesTwotypesofflumesaredesignedtofitdirectlyinpipelinesinmanholes:Palmer-BowlusflumesandLeopoldLagcoflumes,andtheyaresizedaccordingtothepipediameter.Thetransducerlocationsdifferbetweenthesetypes;however,bothdependuponthepipediameter.TheupstreamlocationofthetransducerinaPalmer-Bowlusflumeisthepipediameter‘D’dividedbytwo,asshown:

TheLeopoldLagcoFlumeheadlevelmeasurementrequiresthetransducertobelocatedasshowninthefollowingtable:

Flumesize(pipediameter

ininches)

Pointmeasurement

centimeters inches

12 2.5 115 3.2 1.25

18 4.4 1.75

21 5.1 224 6.4 2.530 7.6 342 8.9 3.548 10.2 454 11.4 4.560 12.7 566 14.0 5.572 15.2 6

Tipsforeffectiveopenchannelflowmeasurement

Ensuretheprimarydevice(weirorflume)istherighttypeandsizefortheexpectedflowrate,andensureitisinstalledproperly.Discrepanciesfromthestandarddesign,dimensions,orsetupwilladverselyaffecttheaccuracyofflowmeasurementdevices.Ensurethatitisproperlycleanedandmaintained.Anybuildupofsedimentorvegetationcaninfluenceflowandflowmeasurement.Checkupstreamconditionsthatmaycreatewavesorsurging.Hydraulicjumps,flowpipes,ordropsinapproachpipeslocatedclosetotheflumecaninterferewithmeasurement.Wheninstallingflowmeasurementdevices,followtheinstallationguidelinesintheinstructionmanualtoensurecorrectsetupandtobeawareofanylimitations.Fieldcalibrationoftheprimaryelementwilltellyouiftheactualheadcorrespondstothehead-to-flowcalibrationinformationsuppliedbythemanufacturer.Ifnot,anewcurvecanbedeterminedthrough

fieldtesting.Thisisessentialonspecialapplicationsornon-standardweirsandflumes.Installtheheadmeasuringdeviceinarelativelycalm,stableportionofthechannel.Itshouldnotbepositionedinachannelapproachthathashighvelocityofwater,turbulence,gates,valves,pumps,orasuddenchangeinsection.Makesurethemeasurementdevicehasbeenproperlyzeroedinreferencetotheprimarydevice.Whentheflumeisempty,yourlevelsensorshouldreadzero.

MaintenanceIfsignificantperformancechangesareobserved,shutdownthelevelmeasurementsystemandinspectit,startingwiththetransducer.Ensurethetransducerisstillfirmlymounted,wipethefaceifithasbecomesoiled,andcheckthewiringconduittoensureitisallsound.Ifthetransducerworksproperly,checkthevesselsidesfornewobstructionsormaterialbuildup.

Ifthesoundpathisclear,performdiagnosticsatthecontroller.Troubleshootinginformationisclearlymarkedintheinstructionmanual,andotherproceduresincludeanalyzingtheechoprofileforechoquality(strength,confidence,andnoise).

Generally,lowmaintenanceisakeyadvantageofultrasonictransducers.Thepowerfulpulsingactionmakesthefaceself-cleaning.Becausetransducersarenon-contacting,thereisnomaterialbuildup,avoidingthenuisance,danger,andexpenseinvolvedincleaning,adjusting,andrepairingcontactingdevices.

LiftstationsLiftstations,alsoknownaspumpstationsorwetwells,areessentiallyverticallymounted,flatbottomvesselsthathappentobebuiltintotheground.Theyarepartofgravityfedsewagecollectionsystemsandareusedtocollectsewageatonepointandthenpumpit(orliftit)toahigherelevationtoeventuallyendupatthewastewatertreatmentfacility.

Liftstationsarealsofoundattheinlettothewastewatertreatmentfacilityitself.Thewetwelldiffersfromasimpleverticallymountedflatbottomvesselbythepresenceofequipmentinsidethewell:pumps,chains,inletanddischargepipes,back-upfloats,powerlinestothepumps,andladderrungs.Liftstationenvironmentsarealsoverycorrosiveanddirty,andthewatercancontainsolids;thuscontactdevices,likefloats,canprovetobeunreliableovertimeasmaterialbuildupandconstantcontactwearsonthesedevices.Ultrasonictransducers,anon-contactingtechnology,aremountedabovethesewageandonlycomeincontactwithsewageduringabnormalfloodconditions.Thusultrasoniclevelmeasurementprovidesnearmaintenance-freeoperationformanyyears.

Installthetransduceronasturdybracketorhangfrommetalconduit.Themountingheightshouldatleast30centimeters(12”)abovetheexpectedmaximumlevel;locatethetransducerasfarawayaspossiblefromtheinletpipe,pumps,ladderrungs,floats,thewetwellwall,andotherobstructions.Ifextremelyturbulentorfoamy,useastillingwellandfollowtheinstallationguidelines.

Wetwelltransducerselection:

shortrangewetwells[0to8m(0to26ft)]:XRS-5shortrangewellswithobstructedbeampath:XPS-15deeperwells:XPS-15verynarrowwetwells:XPS-30

Floodalert

Ifthetransducerissubmerged,especiallyinapplicationssuchasafloodedwetwell,useatransducerwithasubmergenceshieldthatmaintainsanairpocketinfrontofthetransducer.Thecontrollerrecognizestheuniqueechocreatedbytheairpocket,andthecontrolleroutputsahighlevelreading.

Wheninstallingasubmergenceshield,ensureitisproperlyseatedandevenacrossthetransducer.Checkforleaksbyplacingtheassembledunitinabucketofwaterandseeifanybubblesleakout.Leaksindicatetheshieldhasnotbeenpulleddownfarenoughtoproperlyseatthepressureclips.

NOTE:Asyouselectthetransducer,youalsoneedtoselectacompatiblecontrollertoprocessthesignalfromthetransducertoprovidethefollowing:

levelmonitoringdataloggingadvancedecho-processingtechnologypumpcontrolfunctionsremotemonitoring

Allcontrollermodelsofferbacklitdisplaysforeasyreadabilityandotheradvancedfeaturesthatcanimproveplantefficiency.Consideryourspecificapplicationneedsagainstthemanyfeaturesthatareavailable.

Positioncontrol

Ultrasonicsensingtechnologyhasotherusesthatareoutsideoflevelmeasurementbutthatoperateonsimilarprinciples.Thetransducersactasdistancesensors,indicatingproximityandactivatingalarmsormotorsorswitches.Thisultrasonicpositioningcontrolrequiresthetransducertobemountedhorizontallyandisveryeffectiveintheshippingindustryforoperatingoverheadcargocranesandintheminingindustryformanagingcoalloadingconveyors.

HazardousapprovalsTransducerandtransmittersareinstalledinpotentiallyexplosiveenvironments.Greatcareandeffortistakenduringthedevelopmentoftransducerstoensuretheyaresafeforuseandmeetorexceedtheapprovalrequirementsnecessaryforinstallationintheseenvironments.Notonlymusttheyperformtothedistanceandtemperaturerangesspecified,theymustalsodososafelyinhazardousorexplosiveenvironments.

Undermostgoverningelectricalcodes,itisuptotheusertoensurethatthetransducerortransmitterbeinginstalledhasthenecessaryapprovalstomeettheminimumareaclassificationoftheapplication.TransducersfromSiemensMilltronicscomewithawiderangeofapprovalstomeetthedemandsoftheapplicationsthathaveexplosiveenvironments.Theyvaryslightlyfromcountrytocountryastheworldhasnotadoptedaschemeforglobalapprovals.

ApprovalsSiemensultrasonictransducersaredesignedtomeettherequirementstobeusedinbothgasanddustatmospheresandarecertifiedbyvariousagenciesaroundtheworld.Itisimportantwhenspecifyingandinstalling

anyequipmentinalocationthatisclassifiedashazardoustofollowalllocalelectricalcodesandguidelinesandtopayparticularattentiontothespecifiedratings.

NOTES:Thefiretriangleorcombustiontriangleillustratestheconditionsrequiredformostfires.Threeelementsareneeded:heatorspark,fuel,andanoxidizingagent(usuallyoxygen).Fireispreventedorextinguishedwhenanyoftheconditionsareremoved.

Intheworldofelectricalengineering,ahazardouslocationiswhenconcentrationsofflammablegases,vapors,ordustsoccur.Electricalequipmentinstalledintheselocationsisespeciallydesignedandtestedtoensureitdoesnotinitiateanexplosionthrougharcingcontactsorhighsurfacetemperature.

ControllerinstallationWhilethetransducer/compoundinstrumentinstallationmustbecarefullyplannedbecauseofitsproximitytotheapplication,thecontrollerinstallationcanbedeterminedbytheoperator’srequirements.Thus,iftheoperatorisneartheapplication,thecontrollercanbeplacedcloseby.However,becausethecontrollercanbeinstalledasfarawayas365meters(1200ft),itcanalsobeplacedindoorsandawayfromtheelementswhereitmaybeinstalledindependentlyorinarackasoneofanumberofinstruments.

Whethertheunitiswallmountedorinstalledinarackorpanelwithotherinstrumentsdoesnotaffectperformance.Theyarethesame,regardlessofmountingdesigns.

MountinginstructionsThewallmountandpanelmountunitsinstalldifferentlyandthemanualscontainthespecificinstructions.

Wallmountedunitsmustbemounteddirectlytoawallortoelectricalcabinetbackpanel.Alternatesurfacesmustbestrongenoughtosupportfourtimestheweightoftheunit.

Rackandpanelmountedunitswillfitintoexistingslotsor,aswiththeSITRANSLUT400,willrequiremakingacutouttoaccommodatetheunit.Afullsizecutouttemplateisprovidedwithyourunitormaybedownloadedfromwww.siemens.com/level.

WiringCableisbroughtineitherdirectlythroughthecableglandsorthroughconduit,dependingontheinstallationrequirements:

Cableglands:ifthepurchasedunitdoesnothavepre-drilledcableglandholesorknockout,youneedtodrilltheentryholes.Makesureyouremovethemainboard,beingcarefulnottodamagetheelectronicswithstaticelectricity.Makesurecableglandholesdonotinterferewiththelowerareasontheterminalblock,circuitboard,orcommunicationcard.

Afterlooselyattachingtheglandstotheenclosure,threadthecablesthrough,keepingthepowercableseparatefromthesignalcables.Thentightenglandtoaensurewaterproofsealwhenwiringiscompleted.

Conduit:youneedtodrilltheentryholesorremovetheknockouts,somakesureyouremovethemainboard,beingcarefulnottodamagetheelectronicswithstaticelectricity.Makesureconduitholesdonotinterferewiththelowerareasontheterminalblock,circuitboard,orcommunicationscard.Attachtheconduittotheenclosureusingonlyapprovedsuitablesizehubsforwatertightapplication.Reinstallthemainboardwiththemountingscrews.

NOTES:

PerforminstallationonlybyqualifiedpersonnelandinaccordancewithlocalgoverningregulationsFollowpropergroundingprocedures.Thisproductissusceptibletoelectrostaticshock.Allfieldwiringmusthaveinsulationsuitableforatleast250V.HazardousvoltageispresentontransducerterminalsduringoperationSupplyACandDCterminalsfromapprovedsourcesUsegroundingtypebushingsandjumperssothenon-metallicenclosuredoesnotprovidegroundingbetweenconduitconnectionsEnsureambienttemperatureisalwayswithinitsapprovedrange.Typically-20to50°C(-5to122°F)Mountunitsodisplaywindowisatshoulderlevelandeasyaccessforprogrammingisprovided.MakesuremountingsurfaceisfreefromvibrationLeavesufficientroomtoswingunitlidopenforclearaccessAvoidexposuretodirectsunlight(Provideasunshieldtoavoiddirectsunlight.)Avoidproximitytohighvoltage/currentruns,contacts,SCR,orvariablefrequencymotorspeedcontrollers

SummaryUltrasonicsisaversatileandfriendlytechnologyformanylevelapplications,buttheinstallationrequirementsmustbemetforoptimalperformance.Situatingthesensorortransducerinthepropervessellocation,followingallthesafetyregulationsandapprovalrequirements,andaccountingfortemperatureandpressureconditionswillallensurereliable,accurateperformance.Alwaysaccountfortheconditionswhenchoosingaleveltechnology,andthosewhicharemoreproblematicforultrasonics–dust,vacuum,interference–canbehandledbytheSITRANSradarline.

1Prince,“JoyInRepetition.”GraffitiBridge,1990.2Anydevicethatrestrictstheflowandregulatesitthroughameasurablepoint.

ChapterSix

ApplicationsI’macosmopolitansophisticateofculture

andintelligence.Theculminationoftechnologyandcivilizedexperience.1

Ultrasoniclevelinstrumentsarenotexclusivetoanyoneindustryandarewidelyusedacrossmanybusinessesandapplications.However,therearecertainapplicationswhereSiemensMilltronicsultrasoniclevelinstrumentsoperateparticularlyeffectivelyandaccurately.Acrosstheglobeandoveramillionstrong,theseultrasonicleveldevicesarefoundinthewater/wastewater(W/WW)industry;inmining,aggregate,andcement(MAC)applications;andinthechemicalmarkets.

Regardlessofthetypeofapplication,however,theprimaryrequirementforallindustriesistobeabletomeasurelevelaccurately,consistently,andcosteffectively.Ultrasoniclevelmeasurementmeetstheseneeds

andhasbecometheselectedsolutionformanyindustriessincethe1970s.

ApplicationsMarketslikewater/wastewaterandmining,aggregate,andcementemploylevelmeasurementformanydifferentpurposes,includingprocesscontrolandinventorymonitoring.Eachindustryhasarichhistoryofinstrumentationdevelopment.Ascompetitiongrowsandresourcesarestrained,controllingprocessesandinventoriesisincreasinglycrucialtothebottomline.Accuracyandreliabilitybecomeparamountandcloserattentionispaidtotheinstrumentsusedtomeasureinventoryandcontrolprocesses.Measuringandcontrollingthelevelofmaterialscontainedinstorageandprocessvessels,suchastanks,wells,reservoirs,ponds,bins,andhoppersisoneofthemostcommonproceduresofindustrialinstrumentation.

Inalltheseapplications,ultrasonicsprovidestwotypesoflevelmeasurement:

pointmeasurementcontinuous

Thepointlevelcanalsobecombinedwiththecontinuousleveltoprovidesafetyredundancy.

Notthatlongago,binsandsilosweremeasuredbyknottedropesorbysightlines,withemployeesclimbingtothetopofthecontainerorinsomecasesintothecontaineritself.Thistypeofmeasurementbecameimpractical,andoccasionallydangerous,andcompaniessoughtoutinstrumentationwhichwasaccurateandreliable,andcouldbemonitoredincontrolroomsoractivatedfromremotelocations.Plumbbobsandcontactswitchescouldnotstanduptothestrenuousdemandsofmanyoftheapplications,sonon-contactingultrasoniclevelmeasurementasdevelopedbySiemensMilltronicsinthe1970sand1980swasintroduced

tothemarket.TheruggedreliabilityofSiemensMilltronicsinstrumentslikeTheProbeandtheMultiRangerquicklyproveditselfinvaluableforthefollowing:

reducespillage(overflow)–environmental,losscontrol,legislationcostaccounting–inventoryqualitycontrol–processcontrolbylevelreductionofinventoryinprocess–smallervesselspumpprotection–protectfromrunningdry

TopicsThischapterdiscussestheseapplications,focusingonthefollowingindustries:

cementminingwater/wastewaterfoodchemical

Cement

Thecementindustry,similartomining,reliedonrudimentarylevelmeasurementsystemsformanyyears.Plumbbobsoryo-yos,tiltswitches,andmanualdipsprovidedmostoftheinventoryandprocessinformation.Inthe1970sand1980s,ultrasonicmeasurementappearedonthescenewithsomeoftheearlyMilltronicsAiRangersandLRtransducers,findingmanyusesinthecementindustry.

Theproductionoffinishedcementrequiresnumerouslevelinstrumentsalongtheway,operatingintwocapacities:

asprocesscontrollers,activatingpumps,belts,alarms,andotheractionsasinventorymanagers,monitoringmateriallevelsinsilosandbins

Thecementprocesschartindicatesthemanyareaswhereultrasonicinstrumentsoperateinthecementproductionprocess.OtherSiemensMilltronicsequipment,likebeltscales,weighfeeders,andprocessprotectioninstrumentsalsoplayvitalrolesintheproductionofcement,reinforcingSiemens’roleasatotalsolutionprovider.

PrimarycrushersGyratoryconecrushersarethemostcommon,andtherearegenerallytwomainapplicationsattheprimarycrusher.

Truckpositioning–thetransducerishorizontallymountedinthepathofthereversingtruckandiswiredintoacircuitwhichcontrolsredandgreenlights.Asthetruckapproaches,theultrasonicsystemcontinuouslymonitorsitsposition.Whenitistheproperpositionfordumping,analarmrelayclosesandthegreenlightisactivated,signalingtothedriverthattheloadmaybesafelydumpedintothecrusher.

Rockbox–locatedbelowthecrusher,theultrasonicsystemmonitorsthelevelofthecrushedrock.Alarmsaresettoindicateaclogintheoutfeedandtoindicatewhenaloadcanbesafelydumpedintothecrusher.Alowlevelalarmcanbeprogrammedtomaintainaprotectivelayeroforeintherockboxtopreventfeederdamage.

QuarrystockpilesThecrushedlimestoneistransportedfromthecrushertoastockpilebyastackerconveyor.Theultrasonictransducermonitorsstackoutprofilesandprovidesinventoryestimatesinstockpilestoensureuniformstackout.

Anultrasonictransducermountedontheheadoftheconveyormonitorsthedistancefromthedischargetothetopofthestockpile.Whenthedistancebetweenthetworeachestheprogrammedsetpoint,analarmtriggers,signalingtheneedtoraiseorrotatetheconveyortoanewposition.Thisinventorymanagementisacommonapplicationforultrasonicssystemswheretheruggeddesignandremotepositioningofthecontrollermakeitanidealtechnologyfortheseconditions.

SecondarycrusherInthesetypicallynoisy,wet,anddirtyapplications,ultrasonictransducerssensethelevelofmaterialinthesurgebins.Ultrasonicsystemsarealsousedatin-feedchutestocrushers,monitoringforpluggedchutes.

Here,thePointekULS200monitorsthechuteattheendofaconveyor.Ifthechuteplugs,arelayintheULS200closesimmediately,notifyingtheuserthataproblemexistsandshuttingdowntheconveyor.

RawmillfeedsilosCrushedoreistransportedfromthesecondarycrusherstotherawmillfeedstoragesilo.Hereanultrasonicsystemmonitorstheleveloforeinthesilo.

Thisapplicationisstrictlyinventorymanagement,astheultrasonicsystemmonitorsthecontentlevelsonly.

RawmillTherawmillistypicallyarollermillthatpulverizesrawmaterial,includingadditives,intoafinepowderwhichisthentransportedtothekilnfeed.Blendedrawmaterialsarecontinuouslyfedintotherawmill.

Theultrasonicsystemmonitorstheheightofthemillrollersabovethetable,essentiallymonitoringbeddepth.Operatorsintegratematerialfeedratewiththerollerheighttomaintainaconsistentbeddepth,improvingmillingefficiencyandpreventingtherollersfromstrikingthemilltable.

KilnfeedsiloCrushedmaterialfromtherawmillistransportedtothekilnfeedsilo(sometimescalledContinuousFeedSiloasmaterialisconstantlyfedinandoutofthissilo)whereitisstoredandpreheatedinpreparationfordeliveryintothekilnitself.Ultrasonicsmonitorsthelevelwithinthesesilos,butwithonlyalimitedrangeduetotheextremelydustyandturbulentenvironment.

Inrecentyears,manykilnfeedsiloshavebeenoutfittedwithSiemensSITRANSLR560radarleveltransmitterswithgreatsuccessatovercomingtheharshenvironments.Ultrasonicsmaywork,however,

dependingonthedustlevels,andisacost-effectivealternativetoradarinappropriateapplications.

Clinkerstorage

Thematerialleavingthehotkilniscalledclinker.Ranginginsizefromdusttofistsizedclumps,theclinkerisstoredinsilosbeforebeinggroundintoafinepowder.Becauseithascomeoutofthekiln,theclinkerisquitehot.

Toworkeffectively,powerfulhightemperaturetransducersliketheXLT-60measurethelevelintheclinkersilos.Becauseclinkerapplications,althoughdusty,arenotasdustyaskilnfeedsilosorfinishedcementsilos,ultrasonicsisaviablechoiceforthisapplication;however,moreusersareswitchingtoSITRANSLR560radarbecauseofitsimprovedperformance.

AdditivebinsandcoalstoragesilosThesebinscontainmaterialsthatareaddedtotherawmillprocessandaremixedwiththecrushedlimestonebeforethekiln.Theyalsoholdthematerialsthatareaddedduringthefinalgrindingoftheclinker.Thesebinscontainsand,ironore,flyash,gypsum,plaster,orothermaterialsusedtoadjustthecompositionofthecement.

Thecoalsilosstorethecoalthatisburnedinthekiln–theheatfromtheburningcoalisresponsibleforthechemicalchangesoftherawfeedintoclinker.Ultrasonicsystemsmonitorthelevelinthesebinsforinventorypurposes.

FinishedcementsilosThesesiloscontainfinishedcement.Oncetheclinkerandotheradditiveshavegonethroughtheballmills,thematerialisreducedtoaveryfinepowderandisconveyedtostoragesiloswhereitwaitsforbulkshippingviatrainortrucking,orforfurtherproductionintobagged,finishedcement.

Finishedcementisextremelyfineandthereisverylittlemoisture,whichmakesthisapplicationverydusty.Theperformanceofultrasonicsystemsonthisapplicationisinconsistent–itdependsonmanyfactorsincludingsiloheight,dustcollectionsystem,transducerlocation,transduceraiming,andmethodoffilling.Likethekilnfeedsilos,thisapplicationwastraditionallymonitoredbyanultrasoniclevelsystem.Incaseswherethedustistoogreat,aSITRANSLR560radarleveltransmitteroperateswithgreatsuccess.

MiningInventorymanagementandprocesscontrolintheminingindustrywasaroughbusiness.Thenatureoftheproductmadeitdifficulttoassessvolumeaccuratelyandmostofthecontrolwasdonemanually.Mechanicalmeasurementreliedonyo-yos,oroccasionallynuclearmeasurementforpointlevelcontrol.However,nucleartechnologyisveryexpensiveandhasitsownsafetyconcernsandyo-yosarepronetobreakdown.Processeswerealsovisuallymonitoredbutoftenbrokedownwhenthemonitorwasnotwatchingorawayfromhispost.Crushersjammedupfromtoomuchloadorranemptywhenbinsdrained

early.Efficiencywasthusdifficulttomaintain.Safetywasalsoaproblemasworkersoftenhadtoenterstoragebinstochecklevelsortorepairjammedequipment.

Theimplementationofultrasonicmeasurementhasgreatlyimprovedoperationalefficiencyandsafetyinmining.Thenon-contactingtechnologyallowsforinventoryandprocessmanagementfromthesafetyofacontrolbooth.Crushersandfeedbeltsoperatewithoutinterruptionandloadsareaccuratelyandefficientlyprocessed.Ultrasoniclevelmeasurementoperatesinvariouslocationsthroughoutmining.Someofthem,liketheprimaryandsecondarycrushers,areidenticaltothoseusedinthecementindustry.Otherapplications,asshownintheprocessdiagrambelow,requiretheuseofultrasoniclevelequipmentforprocesscontrolandinventorymanagement.

CrusherOrelevelsinsurgebinsaremeasuredbyultrasonicsystemstomonitorthefeedintoacrusher.Thetransducers,althoughruggedindustrialdevices,mustbemountedfarenoughawayfromthefeedtoreducerepeatedcollisionsfromtheoreitself.

Thecrusherreducestheoretoamuchfinerconsistencysoitcanbeaddedtoanotherprocess.

FineorebinsTheXPStransducerseriesareidealformeasuringfineorelevels,atypicallydustyenvironment.ThemultipointSITRANSLU10controllercanmonitorlevelinthebinsandcanbeprogrammedforpriorityscanningtomonitorbinsthatarefillingatahigherratethanstaticbins.

FlotationcellsTheflotationprocessusedinmineralprocessingbeginsbyinjectingafrothingagentintomineralslurry,thenitpumpsthematerialintoanagitatedopentankoranaeratedflotationcell.

Thevaluablemineralsclingtothefroth,whichisthenscrapedfromthetopoftheslurry,afterwhichthefrothingagentisremovedfromthemineral-richconcentrate.Theconcentratesaredewateredandthewasteisdiscardedastailings.Foranefficientextractionprocess,itisessentialtomonitortheleveloftheslurryandtheleveloffroth.

Duringtheflotationprocessboththeheightandthicknessofthefrothmustbecalculatedtodeterminethedosageoftheexpensivechemicalreagents.Accuracyisimportantasitsavesmoneybyusingonlytherequiredamountofreagentsandbyremovingthemaximumamountofmineralsfromthefroth.

TwotransducersorSITRANSProbeLUsaremountedovertheflotationcell.Thefirstmeasuresthelevelofthefroth;thesecondmeasuresthelevelofthepulp.Thepulplevelisdeterminedbyusingafloatball/targetplateassembly:thefloatballfloatsontopofthepulp,arodwithatargetplateisattachedtotheballandthetransducermonitorsthelevelofthetargetplate.Thelevelofthetargetplateisdirectlyproportionaltothelevelofthepulp.Thesignalsfromthetransducersaresenttoaprocesscontrolsystemwhichcalculatesthefroththicknessandcontrolsthedosageofthechemicalreagentsaccordingly.

ChemicalstorageManychemicalsareusedaspartofmineralprocessingandarestoredonsite.Ultrasonicsystemsareusedforinventorymonitoringofthesechemicals.Non-contactingmeasurementisidealforthistypeofinventorymonitoring,astheaggressivenatureofmanychemicalsmakecontactdangerousorimpossible.

Slurrytanks

Shortrangeultrasonictransducersareflange-mountedaboveslurrytankstomeasuretheamountofliquid.ThePVDFenclosuresprotectthetransducersfrommostchemicalsfoundinslurrytanks.

SumppumpwellsManysumpwellsataminingsitecanbemeasuredbyshortrangeultrasonictransducersformorereliableperformance,especiallywhencomparedtosimplefloatsorothercontactswitches.Themanagementofwater,whetheritbetocontrolfloodingoraspartoftherefinementprocess,iscrucialtothemineoperation.

Orestoragebinsorstockpiles

Oftenoreisstoredinbinsorstockpilesbetweenprimaryandsecondarycrushingstages.Ultrasonicsystemsmonitorlevelinthebinsorstockpiles.Thisapplicationissimilartothequarrystockpilingofmaterialusedforcementproduction.

DiskfiltersAftertheconcentratehaspassedfromtheflotationcellsandthethickeners,diskfiltersdewatertheconcentratebeforeitproceedstothesmelterprocessing.Ultrasonicsystemsmonitorthelevelwithinthefilters

andactivatealarmsifthefilteredcake(thedewateredconcentrate)backsup,thuspreventingaspill.

Applicationone:measuringlevelinflotationcellsOneoftheworld’sleadingproducersofcopperandmolybdenumoperatesacoppermineinthewesternUSA.Theoperationusesaseriesofconecrushersandballmillstoreducecopperoretoveryfineparticleswhicharepulped(mixedwithwater)tocreateaslurry.Smallamountsofspecialreagentsareadded,includingafrotherandacollectorchemicalthatcausesthecoppermineralstosticktothebubbles.Thismaterialispumpedtoaseriesoffrothflotationcellstoconcentratethecopperwhereairisblownintotheflotationcelltank,andthepulpmixtureisvigorouslyagitatedlikeinahigh-speedblender.Risingbubblescarrythecopperparticlesupandovertheedgeoftheflotationtankwherethebubblesbreaksoonaftertheyflowovertheedge.Thecopperisthengroundevenfinerandpurifiedbyadditionalflotationprocesses.

Conditions

needtomeasurethelevelofboththepulpandthefrothtoensureoptimumcopperconcentrateproduction.Thoselevelsprovidefeedbacktotheplant’sprocesscontrolsystemsooperatorscanmakeappropriatechangestovariableslikepulpandairflowaswellastheadditionofchemicalreagents

difficultforlevelmeasurementbecauseofmaterialbuild-upandpluggingthatoccursonmosttypesofleveltechnologiesnarrowmeasurementrequirements:spanforthepulpmeasurement(usingtheProbeLUwithtargetandfloatassembly)is25.5centimeters(10")andthefrothlevelProbeusesaspanofonlyfivecentimeters(2")harshconditionsrequireaveryrobustdevice

SolutionTheSITRANSProbeLUultrasoniclevelmonitorcombinessensorandelectronicsinasinglepackageforeffectiveliquidlevelmeasurementinopenorclosedvessels.ThepatentedSonicIntelligenceecho-processingfiltersoutfalseechoesfromacousticalorelectricalnoisesandagitatorbladesinmotion,givingsuperiormeasurementreliability.

EachflotationcellisequippedwithaProbeLUtomonitorthefrothlevelwhileasecondProbeLUmeasuresthepulplevelbasedonametaltargetattachedtoamechanicalfloatassembly.The4to20mAanalogoutputfromtheProbeLUfeedsflotationcelllevelinformationintotheplant’scontrolsystem.

BenefitsTheSITRANSProbeLUsareveryeasytoprogramandtheyrequirenomaintenance.Theonlysetuprequiredisprogrammingthespanfortheanalogoutputwhichisreadilyaccomplishedintheinstrumentshoporduringinstallation.

AggregateTheaggregateindustryissimilartocementandmininginthatitinvolvesmanyofthesameprocessesandmuchofthesamematerial.Thedifferenceisthatitoccupiesthemediumstage,andwhiletherearesomeprocessesinvolved(seediagram),muchoftherequirementisforinventorymanagementandtransfercontrol.Applicationsrequiringprimaryandsecondarycrushers,aswellasorestoragebinsorstockpiles,areverysimilar,ifnotidentical,totheapplicationsinthecementindustry.Others,likethetertiarycrusher,arethesameasthosefoundintheminingindustry.Therearesomeapplicationsuniquetotheaggregateindustry,andtheseareshownintheprocessdiagram.

Blendingsilosandstoragebunkers

Theselargebunkersstorethecrushedore.LongrangetransducerswithEasyAimersprovidemaximumperformance.Loadingisoftendonebytrippercars,unmanneddevicesthatmovealongatrackoverthebunkers.Thetrippercarspositionthemselvesoveremptybunkersandloadtheore.

Screeningstation

Atthescreeningstation,amultipointultrasonicleveldeviceliketheSITRANSLU10measurestheindividualinventoryofbinsbasedonmaterialsize.

SummaryUltrasoniclevelinstrumentsplayanimportantroleintheMining,Aggregate,andCement(MAC)industries.Therugged,non-contactingtechnologyiscost-effective,accurate,andreliable;andcanbeusedforprocesscontrol,inventorymanagement,andevenasdistancelocatorsforcraneoperators.

EnvironmentalTheenvironmentalindustryisthebiggestmarketforultrasonicsensors.Fromwater/wastewatersystemstocleanwatersystems,sensorsmeasureflow,runpumps,activatealarms,andcontroladditiveinventories.

Collectionsystem:liftstation/pumpstation/wetwellInmunicipalitiesandcitieswithwatertreatmentfacilities,anunderground,gravity-fedcollectionsystemtransportsrawsewagefromresidentialandindustrialuserstothesewagetreatmentplant.Pumpstations(aka:liftstations)aredistributedthroughoutthesysteminplaces

wheregravityneedsahelpinghand.Insidethepumpstation,sewageiscollectedinthewetwell,atransitionpointfromwhichitispumpedout,orlifted,untilitreachesthetreatmentfacility.

Ultrasonicsystemsmonitorandcontrolthelevelofsewagewithintheliftstation.Asyoucanseefromthephotosoftheinsideofaliftstation,therearemanyobstructionsinthewells–thenarrowbeamangleandthenon-contactingnatureofultrasonicsmakeitanidealtechnologyformonitoringwetwelllevels.

AdvancedfeaturesincorporatedintoSiemensMilltronicscontrollersprovidemorethansimplepumpcontrol.TheSITRANSLUT400canmonitorpumpruntime,pumpfaults,pumpstarts,androtatepumpstoeventhewearonthepumpsorwearonepumppreferentially.

TheLUT400hasuniquetimingfeaturesthatadduptogreatbenefits.PumpON/OFFsetpointscanbechangedautomaticallybasedonthetimeofday,avoidingpumpingduringpeakelectricitypriceperiodsandgeneratingenergysavings.TheLUT400realtimeclockcontrolallowspumpsetpointstoalteraccordingtothetimeofday.Inatypicalwetwellinstallation,thiscouldmeanpumpingoutthewellbeforepeakrateandthendeferringpumpinguntilaftertheexpensiveperiod.Penaltiesimposedbyelectricitysuppliersforusageduringpeakhourscanbeavoidedinmostinstances.

TheLUT400pumpcontrolandlevelmeasurementsystemprovidestheoptimumsolutiontomanagecollectionnetworks.Pumpstatusandpumpedvolumearemonitoredusingtheprimaryleveldevice.Digital

inputscapturesiteandpumpdataprovidingacompletelyintegratedsystem.

Pumpingstationsaredesignedtohandlespecificflowrates–establishedbypopulationserved–butdemographicchangesalterrequirementsovertimesodesignvolumecannotbeassumed.Pumpedvolumeprovidesrealtrendingdataforcollectionsystemefficiencymonitoring.

Itisimpossibletomaintaincompletelysealedpipeworkfrompumpingstationtotreatmentworks.Groundwaterinfiltrationisinevitable.Pumpedvolumemonitoringcanprovidenetworkinformationtodetermineinfiltrationlocations.

NetworkcapacitycanbeeffectivelyusedbymonitoringcollectionflowsandtransmittingdataviatelemetrytoaSCADAsystem.Thisallowseffectiveassetmanagementandhelpstodiagnosestructuralproblems.

Combinedseweroverflows(CSO)Combinedsewagesystemscollectindustrial,residential,andstorm(rainwater)inthesamesewernetwork.Undernormalconditions,allofthesewageispipedtothesewagetreatmentfacilityfortreatmentanddischargedbackintotheenvironment.However,duringstormconditions,flowsincreasedramaticallyduetorunoffandoverflowsoftenoccur.Whenthishappens,thesewageandrainwateroverflowsaredischargedwithouttreatmentintotheenvironment–stream,ponds,orrivers.Theseoverfloweventsmustbeloggedforregulatorycompliancewiththetime,amount,andlocationrecorded.Ultrasonicsystems,liketheLUT400,canmonitorCSOsandrecordoverflowswhichcanbeusedforregulatorycompliance.

StormwaterpondsInsomecaseswhereoverflowsoftenoccur,stormwaterretentionpondsareinstalledtocollectthesewageandrainwaterandpreventrunofftoneighboringstreams.Oncethestormhassubsided,thewaterispumped

backintothecollectionsystemfortreatment.Ultrasonicsystemsareinstalledtomonitorthelevelinthesepondsandalertuserstothepresenceofstormwaterandofpossibleoverfillingofthepond.

Wastewatertreatmentplant

MainliftstationThemainstationisalargeliftstationlocatedatthesewagetreatmentfacility–alltheremoteliftstationswithinacityeventuallypumptheirsewagetothiscentralstation.Thisapplicationissimilartotheremoteliftstation;however,thewetwellismuchlargerandtherearegenerallyfewerobstaclesorobstructions.Ultrasonicsystemsmonitorthelevelandcontrolthepumpsthatconveythesewageintotheplantaswellasthesewageholdingsandprocessesintheplantitself.

Overflow/stormtankThisoverflowtanklocatedatthesewagetreatmentfacilityprovidesthesamefunctionasstormwaterponds.Actingasholdingfacilities,theycollectthecombinedsewageandstormrainwaterwhenthetreatmentplantisworkingatitsmaximumcapacity.Oncetheincomingflowtotheplantdropsbelowmaximumcapacity,theoverflowispumpedintothetreatmentworksforprocessing.

Intakeflow(influentflume)Flowtothefacilityneedstobemonitoredandcontrolledtomaintainplantefficiency.Ifinletflowexceedstheratedcapacity,itisdivertedtostormholdingtanks(seeabove)andlaterpumpedbackthroughtheinletonceflowsreturntonormal.

InletflowisoftenmonitoredusinganopenchannelprimarymeasuringdevicelikeaflumeorweirandSITRANSLUT400,asecondarymeasuringdeviceprovidinghighaccuracylevelmeasurementusingultrasonictechnology.

Flowdatamustbeloggedtoensurethefollowing:

thatthetreatmentplantoperateswithintolerancescompliancereportingforlocalenvironmentalregulationsisaccurate

BarscreenInorganicdebrisandmaterialiskeptfromenteringthetreatmentplantbybarscreensplacedintheinletchannel.Abuildupofdebrisontheupstreamsidecausesareducedlevelonthedownstreamsideofthe

screen.Whenenoughdebrisaccumulates,arakeisactivatedtoclearthescreenandmaintainflow.Thedebrisismaceratedanddriedbeforedisposal.

ASiemensHydroRanger200usestwoultrasonictransducerslocatedateithersideofthescreentomeasuretheupstreamanddownstreamlevels.ArelayonboardtheHydroRanger200activatestherakeatauser-defineddifferentialleveltocleardebris.Theuseofnon-contactingultrasonictransducersensuresyearsofmaintenancefreeoperation.

Solidslevelmeasurement

Sandanddebrisremovedbytherakeandgritchambersiscollectedinavessel(oragarbagedumpster)monitoredbyanultrasonicsystem.Oncefull,theultrasonicsystemprovidesanalarmtotheusersothatthevesselcanbereplacedwithanemptyone.

ChemicaltanksChemicals,likethealumusedasaflocculentinclarifiersorthechlorinethatdisinfectsthewaterbeforefinaldischarge,arestoredon-sitefordailyuse.Ultrasonicsystemsmonitorthelevelinthesevesselsforinventorypurposes.

Finaleffluent/dischargeflow

Alltreatmentplantdischargestotheenvironmentmustconformtodistrictlegislationregardingquantityandquality,soaccuracyiscriticalatthisstage.Primarydevicessuchasweirsorflumesthroughwhichtheflowischanneledprovidehighaccuracymeasurementandareoftenused.Thequalityofthedischargemustbemonitoredandistypicallydonewithasampler.

Toachieveaccurateflowmonitoringandcomplywithlegislationrequirements,aprimarymeasuringdevicecombinedwiththeLUT400openchannelmonitorcanbeused.TheLUT400convertshighaccuracyultrasoniclevelmeasurementtoaflowvalueusingknownheadversusflowformulaorBritishandISOStandards.Fulldataloggingcapabilitiesareavailabletologdailyflowtotalsandflowrates.

SludgetreatmentThesludgethatisleftafterthewaterhasbeenremovedisatoxicsoupofwasteproductsthatmustbetreatedverycarefully.Itshandlingishighlyregulatedandallprocessesarecarefullyscrutinized.Measurementofinventorythusplaysanimportantroleinsludgemanagement.

Digestergas

Biogases(methane)fromthedigesterareoftenstoredinagasholderwitha“floating”roof.Thesegasesarere-usedtoprovideheatingfortheplantorforlocalpowergeneration.Ultrasonicsystemsareappliedtomonitortheheightoftheroofandthustheamountofgaspresent.

DigesterlevelThisapplicationwasoftendonewithultrasonicswithlimitedaccuracyduetheeffectsofmethaneonthespeedofsound.Currently,radardevicesliketheSITRANSLR200andProbeLRprovideamoreaccurate,cost-effectivereadingandarereplacingultrasonicsasthefirstchoicetechnologyforthisapplication.

Dewatering/vacuumfilterThelevelofsludgeinthevacuumfilterismonitoredbyultrasonicsandcontrolsapumpthatwillcallformoresludgetothefilterfromthesludgetankwhenthelevelistoolow.

Environmentalapplications

Applicationone:liftstationcontrolAmunicipaldistrictinEuropeneededtoupgradeitswatertreatmentsystemandturnedtoSiemenstorenewthelocalmeasurementdevices,andcontrolequipmentandautomationsystem.Theyalsowantedtoincreaseremotemonitoringcapacity.

ConditionsTheprojectneededtointegrateexistinglevelmeasurementsolutionssuchashydrostaticpressuresensorswithanewultrasoniclevelmeasurementsystems,liftpumpcontrolmonitoring,anddataacquisition.

116pumpingstations18associatedcommunitiespopulationof140,000

SolutionSiemensinstalledthefollowingsystem:

SITRANSLUT400–thehighlyaccurateultrasoniccontrollerfromSiemenswaschosenforthepumpstationmonitoringandequipmentcontrol.EchomaxXRS-5ultrasonictransducerswereinstalledtomeasurelevel.

WithpatentedSonicIntelligenceecho-processingtechniques,theLUT400monitorsandcontrolsliquidlevelsinwellsand/orliquidflowinflumes,weirs,oropenchannels.ItsthreerelayscontrolalarmsorpumpsThesystemmonitorsliftstationsandcollectsdatasuchasstateofoperationandpumpruntime.Ateachliftstation,anLUT400controllerprocessessignalsreceivedfromlevelmeasurementtransducers.

DataistransmittedvialandlineusingSITRANSRD500tothecontrolroomatthedistrictheadoffice.TheSITRANSRD500hasabuilt-inwebserver,FTP,andemailclientwhichallowstheprocesstobemonitoredremotely.AlarmnotificationsarecommunicatedthroughemailandSMStextmessagestooneormorerecipientstoensurethatappropriateactionsaretakenbypersonnel.

BenefitsTheSITRANSLUT400provedareliableandcost-effectivesolutionforpumpcontrol,requiringlessmaintenancethanthepressuresensors.SITRANSLUT400increasedefficiencyandreducedmaintenancecosts.

InstallingSITRANSLUT400alsooptimizedspaceintheelectricalcabinetbyrationalizingcomponentsandreducingwiringtimes.ExistingequipmentwaseasilyintegratedwithLUT400andithooksseamlesslyintothecentralcontrolsystem.

Applicationtwo:wastewaterplantcontrolAmajorCanadiancitywithapopulationexceeding300,000neededtoupgradeitswastewaterplantsandpumpstations.

Allthelocationsweretolinkintoanewhigh-speeddatacommunicationsnetwork,integratingthemintoaSCADAsystem.Toensureaccuratedatagathering,thecityrequiredreliablefieldinstrumentsthatcouldintegrate

intothenetwork.Afterconductingaseriesofrigoroustestsonultrasonicleveltechnologiesfromseveralsuppliers,thecitychoseSITRANSLUT400withitsonemillimeteraccuracyandSiemensreliability.

Conditions

sixwastewatertreatmentplantshandlingatotalof208millionliters(55milliongallons)perdaythirty-eightpumpingstationswithcapacitiesrangingfrom0.75–21millionliters(0.2millionto21milliongallons)perday.twenty-fiveofthe38areduplexpumpingstations;therestarecomplexpumpingstationswithhugevariablefrequencydrive(VFD)pumps

SolutionSiemensinstalledtheLUT400inthe25duplexpumpingstationsforcontinuouslevelmonitoringandpumpcontrolandputSiemensEchomaxtransducers©2intothewetwells.

TheuniquepanelmountdesignoftheSITRANSLUT400madeforquickinstallation,andforeasyaccess.ThecontrollerswerenetworkedintoaPROFIBUScommunicationsystem.TheSCADAsystemreceivesinformationfromallstations,aswellasotherplantinformation,onthenetwork.AtthemorecomplexpumpingstationsemployingVFDpumps,theLUT400measureslevel,andtheanalogoutputisfedintoaPLCforpumpcontrolandremotetelemetry.

BenefitsTheultrasonicsystemsperformreliably,anddatacollectionfromthemanysitesisnowfastandaccurate.Operatorscanmonitorandcontroltheplantsitesfromthecentrallocation.Theautomatedsystemismoreefficient,andhasgeneratedsavingsinenergyandmaintenancecosts.StandardizingonLUT400simplifiedinstallationandtraining,savingstafftimeandmoney.

Applicationthree:smallcityoperatesatahighlevelAsmallbutgrowingCanadiancityneededtoincreaseitsfreshwateroutputduetoasteadilygrowingpopulation.Thisneedwascombinedwitharequirementtocontrolcostsandimproveefficiency,allthewhileimplementingnewregulationsrequiringenhancedsafety,training,andenvironmentalprotection.

Conditions

Populationof74,000andgrowingThesystembringswaterfromariver,cleansandtreatsit,thendistributesittoresidentsApproximately400kilometers(250miles)ofwatermainsPumpsanaverageof45millionliters(12millionUSgallons)ofwateraday

SolutionThewaterplantembracesfullyautomatedoperations.AllprocesspointsareintegratedfullyintoacentralSCADAsystemforcontinuousmonitoringandcontrol.Levelmonitoringisacriticalneedforawaterplant,andSiemensinstalledmorethan40pointsoflevelinthemainplantovertheyears.Theymonitortheriverlevel,gatepositionintheriver,aswellaslevelintheflocculationtanks,sedimentationbasins,settledwatertrough,filterbeds,finishedwaterstoragereservoirs,chemicaltanks,andotherapplications.Anultrasonicdevicemonitorsthefloorasasafeguardtodetectanyspillagefromaleakorrupturedpipe.

Atthecity’svariousstations,reservoirs,andelevatedwatertanks,thereareanother20pointsoflevelbeingconstantlymonitored.Signalsfromremotesitesaretransmittedbyradiolinktotheplantcontrolcenter.

BenefitsTheaccurateandresponsiveSiemenssensorsconstantlymonitortheriverrateofchange,acriticalmeasurement.Theyalsoprovedtheirpreventativevaluewhenoneoftheinteriortanksdevelopedaleakandanalarmwasimmediatelytriggered,preventingaseriousproblem.BecauseSiemenshasbeenthevendorofchoiceforquitesometime,theplantactuallyhasanumberofolderinstrumentmodelsoperating.Theseinstrumentsstillperformreliablyandaccurately,keepingmaintenancecostsdown.TheplantoperatorscreditSiemensultrasonicsystemswithhelpingthemintheireffortstodeliverqualitywaterefficientlytocityresidents.

Applicationfour:protectingwaterqualityAUKwatercompanyoperatesalargesubmergedmicrofiltrationplantthatservicesanentirecitywithpotablewater:

Theplantcapacityis84megalitresadaySixfiltrationcellsthatremoveparticlesassmallas0.2microns,includingbacteria,algae,andmicroorganisms.

ConditionsTwotypesoflevelmonitoringisrequired:

monitoringwaterlevelsiscrucialbecausethefltersrequireperiodicbackwashingwithfiltrateandair,andwithchemicalswhenthemaximumtransmembranepressureisreached.Afilterblockagemakesthewaterlevelrise,signalingtheneedforabackwash.monitoringthelevelsofthechemicalsonsite,includingsodiumhypochlorite,sulphuricacid,sodiumbisulphate,andsodiumhydroxide(causticsoda).Reliablelevelmeasurementofthechemicalstoragetanksiscrucialtosuccessfulprocesscontrol,inventorymanagement,andoverflowprevention.Levelsmustalsobemeasuredintheclean-in-placetank(CIP)andthewashwatertank.

Solution

SiemensEchomaxXRS-5ultrasonictransducersareinstalledona“tophat”sectionofeachchemicaltankusingaflangemounting.Thesetransducersarehermeticallysealedinchemicallyresistantenclosuresforreliableoperationinharshenvironmentsorchemicalapplications.ThetransducersarewiredtotheSITRANSLUT400controllerswhichfeedthe4to20mAoutputdirectlyintotheSCADAcontrolsystem.

Operatorscannoweffectivelymonitorthelevelineachofthestoragetanks.Theultrasonicsystemsworkeffectivelywithoutthecomplexityofhigherpricedsolutionsandwithouttheproblemsofcontactingandmechanicaldevices.PatentedSonicIntelligenceadvancedecho-processingtechnologyisbuilt-intoprovidesuperiorreliability.

Benefits

Non-contactingultrasonictechnologyrequiresalmostnomaintenance,andeliminatesworriesaboutchemicalcompatibility.Thereisnodriftfrommechanicalwear,andtheyarenotaffectedbydensitychangessothereisnoneedforrecalibration.

Theyareeasytoinstallandreplace,withnoneedtodrainthetank.Topmountingeliminatestheneedforisolationvalvesrequiredforside-mountedpressuretransmitters.

FoodindustryLikemanyotherindustries,foodapplicationscanbedividedintotwotypes,storageandprocess.Furthermore,storagecanbedividedintosolidsandliquids.Theseapplicationsarequitedifferentandeachpresentsitsownunique,butnotinsurmountable,challengesforlevelmeasurement.Forexample,a30meter(100ft)silofullofcornstarchisverydifferentthana1.5meter(5ft)stainlesssteelcookervesselfullofspaghettisauce.

SolidsSolidstorageapplicationsarecommon;mostfoodfactoriesneedtostorealargesupplyofrawmaterials.Cerealmillingcompanies,grainshipping,petfood,andbreweriesstorerawgrains(wheat,corn/maize,barley)inlargetallsilosorconcretebunkers;anXPS-30mountedwithanEasyAimerIImeasuringgrainatabrewingcompanyisshownhere.

Generally,longerrangetransducersareusedastheapplicationsareusuallygreaterthan15meters(50ft)andtheextrapoweroflongrangetransducersovercomesattenuationduetodust(evenondustyapplicationsthatmaybelessthan15meters(50ft)).EasyAimersarerecommendsothetransducersaremountedperpendiculartothematerialsurfacesthatoftenhaveasteepangleofrepose.Onexcessivelydustyapplications,theSITRANSLR560radaristherecommendedinstrument.

Often,manyofthesametypeofvesselsarefoundtogether,acerealmanufacturerstoringalargeinventoryofgrain,forexample,anditisbeneficialtouseamulti-pointsystemliketheten-pointSITRANSLU10tomeasureinventoryoftenvesselswithonecontroller.

SanitaryconnectionFoodprocessingvessels,whetherblendingfruitjuices,cookingsauces,ormixingicecreamflavours,aremuchsmaller,aremadeofstainlesssteel,andarecleanedregularly.Asanitarymountingprocessconnectionisrequiredtoensurecleanliness.TheProbeleveltransmitterandtheXCT-8transducerareavailablewitha4-inchsanitaryclampstyleprocessconnection.

Temperature

Thetransducerhastobeabletowithstandthecleaningtemperaturesduringthesanitizingprocess.Inmostcasesthetemperatureisintherangeof80°Candamildcausticsolutionissprayedontheinsideofthetank.Iftheleveldevicecannotwithstandthecleaningtemperaturethenitmustberemovedandsanitizedseparately;ifthecleaningtemperatureiswithintherangeofthetransducerthenitcanbecleanedinplace(oftenreferredtoasCIP).

ObstaclesTheinsideofaprocesstankhasnumerousobstaclesthatthelevelsystemhastotakeintoaccount.Theroundballisacleaningballandthesanitizingsolutionissprayedintothetankfromthisball.Whenmountingatransduceronafoodprocessvessel,makesurethatthecleaningballisnotwithinthebeampath.

LiquidsLiquidstoragevesselsarethemoststraightforwardmeasurementsforultrasonicsystemsinthefoodindustry.Thevesselsaregenerallylessthanfivemeters(16.5ft)inheightandhavelittleornoagitation.Theycontainfoodoils(vegetableoils),sugarsyrups(glucose,molasses),cleaningsolutions,water,acids,orfats.

Chemicalindustry

Applicationswiththechemicalindustryaregenerallylimitedtorawmaterialstoragevesselsorfinishedgoodsstorage–theprocess/reactorvesselsareusuallytoohotortoohighpressureforultrasonictechnology.However,otherancillaryapplicationsinthechemicalindustryrequireultrasonictechnology.Forexample,thesemaybethevesselsstoringlubeoilsforon-sitemachinerymaintenanceorcontainingthepre-treatmentwastewaterbeforeflowingitintothemunicipalwastewatertreatmentsystem.

Storagevesselsaretypicallybulkstorageofliquidchemicals,hydrochloricacid,orsulfuricacid.Storedinvesselstenmeters(33ft)orless,theypresentnochallengestotheultrasonicsystemotherthanrequiringthatthewettedmaterialofthetransducerhousingiscompatiblewiththematerialinthevessel.

Ultrasonicsisalsousedforinventorycontrolonfinishedgoodsstoragesilos.Apopularapplicationisthecontainmentofplasticpelletsinsilos.TheSITRANSLR560isalsoverysuitableforthisapplication.

Thesilosaretallandnarrowandthepelletsarepneumaticallyfed.Aimingisrequiredbecausethepelletshaveaslightangleofreposeandproperaimingincreasesthereceivedechostrengthandprovidesamorereliablesignal.

Applicationone:monitoringfluidlevelofdrillingmudpitsandtanksAsupplierofcontrolandinformationsystemsforhighqualityoilandgasdrillingequipmentwaslookingforatechnologytomonitorfluidlevelsindrillingrigmudpitsortanks.Drillingmudisanessentialcomponentindrilling,andprecisemonitoringofthetotalmudvolumeinarig’sdrillingfluidcirculatingsystemisessentialforsafe,efficientoperation.Varioustechnologies,includingmechanicalfloats,hadfailed.

Drillingfluidor“mud”ispumpeddownthroughthedrillpipewhereitblowsoutthroughnozzlesinthedrillbit.Themudthenflowsbackuptheholetothesurface,clearingtheholebycarryingtheformationcuttingsalongwithit.Themudlubricatesthedrillpipeandcoolsthedrillbit.Theweightofthemudcolumnpreventsformationfluidsfromenteringthewellbore,preventinga“blowout.”Throughhydrostaticpressure,italsohelpspreventcaving.Anincreaseinfluidlevelsmayindicategas,oil,orotherfluidshaveenteredthewellbore.Ifdrillingfluidlevelsdecrease,circulationisbeinglosttotheformation.Leftunchecked,eithersituationcouldresultinablowout.

Conditions

Mudtanksaregenerallysquareorrectangularinterconnectedsteeltanksusedonoffshoreoilrigstocontainthelargevolumesofdrillingmudflowingthroughthedrillingfluidcirculatingsystem.Onlandrigs,thesetanksarecalledmudpits,athrowbacktothedayswhenearthenpitsweredugtocontaindrillingmud.

SolutionThecompanyinstalledSITRANSProbeLUs.Thenon-contactingultrasonictechnologydoesnotbecomefouledwithmaterialnoraretheremovingpartstowearout,makingitpracticallymaintenancefree.TheProbeLU’sadvancedechoprocessingignoresmovingagitatorbladesandlocksontothetargetedmateriallevelinsteadofobstructions.Withits2-inchNPTconnection,itissimpletomount.Itcanbeinstalledandcalibratedregardlessofmateriallevelswithinavessel.Oneunitworkswithallvesselsizes.Itsrangegoesfromlessthan30centimeters(oneft)tomorethanfivemeters(16ft).ThereisanIntrinsicallySafeversionavailableforFMClassI,Division1applications.

BenefitsThecompanynowhasareliablenon-contactlevelmeasurement,avoidingelectromechanicaldevicesthataresubjecttowearandtear.Thesavingsfromreducedmaintenanceorreplacementcostsaresignificant.

Bothsafetyanddrillingefficiencyarealsoincreasedasthecompanyprovidesprecisemonitoringofacriticaldrillingvariable.

Applicationtwo:inventorycontrolOneofthelargestby-productsrecoveryfirmsinNorthAmericaneededtomeasurelevelintheirholdingtanks.Thetanks,indoorandoutdoor,holdavarietyofchemicalandoilwasteproductsreadyfortreatment.Governmentenvironmentalregulationsinsuchafacilityarenecessarilyverystringent.

BeforecontactingSiemens,thecompanyusedfloatswithexternalsightboardindicators.Thesemechanismsoftenstuckorfroze,andthemalfunctionsmademeasurementunreliable.Plantpersonnelhadtoconductfrequentvisualcheckstoverifythatthereadingswereaccurate,andtodetectandfixequipmentproblems.Unreliablereadingsalsomadeinventorymanagementproblematic.

Conditions

Outdoortanksfortreatingandstoringsolvents,wasteoils,andcausticsIndoortanksforhazardousprocesswaterMandatoryhigh-levelalarmstoguardagainstspills

SolutionSiemensinstalledacompleteultrasoniclevelmeasurementsystemthatoffersbothcontinuouslevelmonitoringaswellashigh-pointleveldetection.Eachofthe19tanksisequippedwithanEchomaxultrasonictransducer,connectedtooneofthreeSITRANSLU10transceivers.ThesystemusespatentedSonicIntelligencesoftwareforenhancedreliability.LeveldataisfedtoanHMI(Human-MachineInterface)locatedinsidethetestinglab.ASmartLinxinterfacecardconvertsthesignalstoModbusRTUprotocolusedbytheHMI.MaterialleveldataisroutedtothreeSAM-20devicesthatcontrolthehigh-levelalarmindicators,identifythetanks,andconnecttoaPLCthattriggersbothlightandsoundalarmsifhighlevelsoccur.

BenefitsWithautomated,reliablelevelmeasurementinplace,personnelnolongerneedtowastetimewithfrequentmanualinspections.Non-contactingultrasonictechnologyrequiresalmostnomaintenanceand,withnomorefloatmechanicalproblems,thecompanyhasgreatlyreduceditsmaintenancecosts.

Tanklevelsaremonitoreddirectlyinrealtime.Withexactcontentandstoragedataalwaysavailableattheclickofabutton,thelabcanscheduledeliveriesknowingstoragespaceisavailable.Reliablecontinuousmonitoringallowsforeffectiveschedulingandaccurateinventorycontrol.Thehigh-pointlevelalarmseliminatetheriskofspillage,andhelpenhanceplantsafety.

Otherindustries

Applicationone:ultrasonicsystemforPeterboroughLiftLockThePeterboroughLiftLockNationalHistoricSiteofCanadaisoneof40locksontheTrent-SevernWaterway,anationalhistoriccanaloperatedbyParksCanada.

Originallybuiltformarinecommerce,thewaterwaystretches386kmfromLakeOntario’sBayofQuintetoGeorgianBay.Today,itisaworld-famoustouristdestinationforrecreationalboatersandisregardedasoneofthefinestinterconnectedsystemsofnavigationintheworld.ThehistoriclockstationsoftheTrent-Severnarecentraltonumeroustownsandvillagesinthewaterwaycorridor.ThePeterboroughLiftLock(150kmnortheastofToronto,Canada)istheworld’shighesthydraulicliftlockandanengineeringmarvelthatattracts160,000visitorsannually.

ConditionsTheLiftLockisamassiveconcretestructuresupportingtwochamberswithramsconnectedinaclosedwaterhydraulicsystemwithacrossovervalve.Operatorsfloodtheupperchamberwithanextra30centimeters(12")ofwater,thenopenthecrossovervalvesothattheheavyupperchamberpushesdown,forcingthelowerchamberup.Boatsinthechambersareliftedorloweredabreathtaking19.8m(65ft)inonlyminutes.Smoothoperationdependsonensuringadifferentialof30centimetersofwater.Theweightdifferentialoftheextrawaterintheupperchamberdrivesthesystemthatraisesandlowersboats.

Throughoutitshistory,theLiftLockhasreliedonmanualwaterlevelmeasurementbut,whentheLiftLockcelebratedits100thanniversaryinJuly2004,itreceivedahightechbirthdaypresentfromSiemens

Milltronicswhoprovidedanewultrasoniclevelmeasurementsystem.“ThelevelmeasurementsystemisourbirthdaypresenttotheLiftLockasitturns100andourgifttothecommunityasSiemensMilltronicscelebratesits50thanniversarythisyear,”saidDaveBignell,PresidentandCEOofSiemensMilltronicsin2004.“We’reproudtohaveourtechnologyinstalledinthislandmarkstructure.”

SolutionEchomaxXRS-5transducersarenowmountedupstreamanddownstreaminABStubesandenclosedinaluminumpipe.Thisprotectstheultrasonicdevicesfrombeingbumpedordamagedbyboatsinthelock.ThetransducersarewiredintoaMultiRangertransceiverlocatedinthecontroltoweranditprocessesthesignalsandprovidesadigitalreadoutofthewaterlevels.MultiRangerisknownforitsreliable,accuratecontinuouslevelmeasurement.It’salsocompact,whichisimportantinthetightquartersoftheLiftLock’ssmallcontroltower.

Benefits“Thenewsystemhelpsensureproperoperationofthelock,”saysBruceKitchen,WaterControlEngineerfortheTrent-SevernWaterway.“Theultrasoniclevelsystemenablesthelockmastertotellataglancetheelevationsofthewaterupstreamanddownstream.Accuratelymonitoringandcoordinatingtheselevelshelpourstaffachievetheoptimumelevationdifferentialfortheworkingofthisheritagemachine.”

ChapterSeven

Bestinclass–theultrasonicproductlineYou’resimplythebest,betterthanalltherest.1

TheSiemensMilltronicslineofsophisticatedultrasonicinstrumentsisdesignedtomeetlevelmeasurementchallengeswithaccuracy,reliability,andlongevity.Theinstrumentsrepresenttheexperiencegatheredfromanexcessofamillionapplications2andreflectthecollecteddedicationandinnovationofoverahalfacenturyofservicebyourenthusiasticandimaginativepeople.

Fromtransistorstochips,frommilliampstoPROFIBUS,frommetaltoPVDF,fromaconvertedgaragetoamultinationalcompany,SiemensMilltronicshaspushedtheboundariesofultrasonictechnologytotakealeadershiproleinthewater/wastewaterindustryonaglobalscale.

Ourultrasonicinstrumentsmeetthechallengeofmanytypesofapplications,andtheSiemensMilltronicscatalogcontainsinstrumentsforthemall.Inthefollowingpages,weofferbriefdescriptionsofbothourlatestandgreatest,aswellasthetriedandtrue.Combined,theyformagroupreadytotakeonthemeasurementchallenge,atanylevel.

SITRANSLUT400SITRANSLUT400isahighaccuracysystemthatexcelsatcontinuouslevelmonitoringandcontrolinliquid,solid,orslurryapplicationsinawiderangeofindustries.

Threemodelsmakeuptheseries:

SITRANSLUT420LevelControllerSITRANSLUT430Level,Pump,andFlowControllerSITRANSLUT440HighAccuracyOpenChannelMonitor(OCM),whichalsoprovidesafullsuiteofadvancedlevel,volume,andpumpcontrols

Thesecontrollersareaflexiblesolutionforaworldofapplications:water/wastewatermonitoringandpumping,inventorymanagement,crushercontrol,truckload-outs,oranythinginbetween.

Thesystemiseffectiveinwetwells,weirs,andflumeswherebuildupandturbulencearetypicaloperatingconditions.Itcanbecustomizedtomeetyourspecificapplicationneeds—frommeasuringflowrateinanarrowflumetovolumeinaferricchloridestoragebank.

Inadditiontomonitoringflowrateinsewageworks,SITRANSLUT400canmonitorindustrialdischargeandproviderainfall/stormwaterstudies,inflow/infiltrationstudies,andsewersystemevaluations.Theprogrammableheadversusflowcurveaccuratelydefinesflowrateonuniqueornon-standardweirsandflumes.

TheLUT400hasdataloggingandisadjustable,rangingfromonceperminutetoonceadayasitrecordstheaverageflowrateforthattimeperiod.Dailyrecordingincludesmin/maxoftemperatureandflowrates,

thetimetheyoccurred,andthedailytotal.Advancedfunctionsincludevariableratelogging.Itcanbepre-programmedtologatahigherratewhenneeded.

TheSITRANSLUT400featuresawall,pipe,orDINrailmountedenclosure,housingelectronicswithahermeticallysealed,corrosion-resistantEchomaxtransducer.Componentscanbeseparatedasfaras365meters(1200ft).

Keybenefitsindustry-leadingaccuracyof±1mm(0.04")givesyouconfidenceinyourmeasurementseasytouse–localuserinterfacewithfour-buttonprogramming,menu-drivenparameters,andWizardsupportforkeyapplicationsoptionalsubmergenceshieldstoprotectthetransducerduringflooding.Patenteddetectionsoftwarecandifferentiatebetweenasubmergedconditionandahighlevel.wall,pipe,andDINrailmountingconfigurationswith¼-turnfastenersforquickaccessandhassle-freewiringwithremovableterminalstripsoutputsforalarms,chartrecorders,controllers,andintegrationofexistingsystemsenergysavingfunctionswithbuilt-inreal-timeclockreal-timeclockcontrolallowspumpsetpointstoalteraccordingtothetimeofday.Inatypicalwetwellinstallation,thiscouldmeanpumpingoutthewellbeforepeakrateandthendeferringpumpingduringtheexpensiveperiod.Penaltiesimposedby‘triads’andsimilarelectriccompanyincentivescanbeavoidedautomaticallyinmostinstances.specialcontrolmodetoreducegreaseringsandotherdepositswithapumpvolumesystemusingpatentedalgorithms,theLUT400continuouslymonitorsinflowpriortoapumpstarting,thuscalculatinganaccurateandtimelyinflowrate.Wheneachpumpstarts,itscurrentcapacityiscalculatedandstored,givingaccuratecalculation

ofpumpedvolumethroughput,unaffectedbyvariableinflow.Theunitdoesnotrequireanydiscreteinputsfromthepumps,oranyformofin-lineflowmonitoring.

Keyapplications

wetwells

flumes/weirs

chemicalstorage

liquidstorage

bulksolidsstorage(gravel,flourbins,grains,cereals)

plasticpellets

crushercontrol

SITRANSProbeLUSITRANSProbeLUisa2-wirelooppoweredultrasonictransmitterforlevel,volume,andflowmonitoringofliquidsinstoragevessels,simpleprocessvessels,andinopenchannels.SITRANSProbeLUisdesignedtomonitorlevelinthewaterandwastewaterindustryandinchemicalstoragevessels.

SITRANSProbeLUfeaturesfield-provenSonicIntelligencesignalprocessingthatincorporatesnewechoprocessingcapabilitiesandthelatestmicro-processorandcommunicationstechnology,providingacontinuouslevelmeasurementrangeofeithersixortwelvemeters(20or40feet),dependingonapplicationrequirements.

SITRANSProbeLUoccupiesauniqueplaceintheultrasoniclandscape.WithitsAutoFalse-EchoSuppression,iteffectivelyeliminatesvesselobstructions,negatinganyinterferencecausedbyextraneousvessel

clutter.Furthermore,itsadvancedsignal-to-noiseratioallowsforclearechoesandamarket-leadingaccuracyfortransmittersof0.15%ofrange.

OtherapplicationconditionslikechemicalcontentsandprocesstemperaturevariationsareeasilydealtwithbecausethetransducerisavailableasETFE3orPVDF4,andaninternaltemperaturesensorcompensatesfortemperaturechanges.

Keybenefitseasyinstallationandsimplestartupprogrammableusinginfraredintrinsically-safehandheldprogrammer,SIMATICPDM,orHART®CommunicatorcommunicationusingHARTorPROFIBUSPApatentedSonicIntelligencesignalprocessingextremelyhighsignal-to-noiseratioAutoFalse-EchoSuppressionforfixedobstructionavoidance

Keyapplications

Storagevessels Waterindustry

lubeoils

juices

vegetableoils

resins

cleanwatertowers

liquidsugars/cornsyrup

fueloils

charcoalfilters

flocculants

stormwaterholdingtanks

chlorinestorage

Sulfuricacidstorage Waterstorage

TheProbeTheProbeisashort-rangeintegratedultrasonicleveltransmitter,idealforliquidsandslurriesinopenorclosedvessels.ThetransducerisavailableinPVDF,makingthedevicesuitableforuseinawidevarietyofapplicationsfromwater/wastewatertopizzasauce.Itisidealforthefoodandpharmaceuticalindustriesasitcanbequicklyremovedforcleaning.

TheProbeisaworkhorse,providingreliableleveldatabasedonSonicIntelligenceechoprocessingalgorithms.Ithasanonboardfilterthatdiscriminatesbetweentrueandfalseechoesfromacousticalorelectricalnoisesandagitatorbladesinmotion,aswellastemperaturecompensation.Italsoprovidesdistancereadingsconvertedfordisplay,analogoutput,andrelayactuation.

Keybenefitseasytoinstall,program,andmaintainaccurateandreliable

transducersavailableinPVDFsanitarymodelavailablepatentedSonicIntelligence®echo-processingintegraltemperaturecompensationuptofivemeter(16.5ft)measurementrange

Keyapplications

chemicalstoragevessels

filterbeds

mudpits

liquidstoragevessels

MultiRanger100/200MultiRangerisaversatile,shorttomedium-rangeultrasonicsingleandmulti-vessellevelcontroller.MultiRangerofferstruedual-pointmonitoring,digitalcommunicationswithbuilt-inModbus®RTUviaRS-485,aswellascompatibilitywithSIMATICPDM,allowingPCconfigurationandsetup.MultiRangercontainsSonicIntelligenceadvancedecho-processingsoftwareforincreasedreadingreliability.

MultiRangerfeaturesthefollowing:

cost-effectivelevelalarming

ON/OFFandalternatingpumpcontrolupto15meters(50ft)measuringrangemonitorsopenchannelflowconvertslevelreadingtovolumemeasuresdifferentialleveloverabarscreenadvancedrelayalarmingadvancedpumpcontrolfunctions

MultiRangeriscompatiblewithchemical-resistantEchomaxtransducersthatcanbeusedinhostileenvironmentsattemperaturesashighas145°C(293°F).

Keybenefitsdigitalinputforback-upleveloverridefrompointleveldevicecommunicationusingbuilt-inModbusRTUviaRS-485compatiblewithSmartLinxsystemandSIMATICPDMconfigurationsoftwaresingleordual-pointlevelmonitoringAutoFalse-EchoSuppressionforfixedobstructionavoidancedifferentialamplifiertransceiverforcommonmodenoisereductionandimprovedsignal-to-noiseratiowallandpanelmountingoptions

Keyapplications

water/wastewater

fueloil

municipalwaste

woodchips

materialswithhighanglesofrepose

bulksolidsstorage

MultiRangermonitoringandstoragevessel

TwoMultiRangersmeasuringammoniatanks

MultiRangermeasuringcanallevelsatPeterboroughLiftLock,Ontario,Canada

SITRANSLU10SITRANSLU10isalong-rangelevelmonitoringsystemforliquidsandsolids,offeringten-pointmonitoringinasingleunitforawiderangeofapplicationstoscanliquids,solids,oracombinationofbothcontainedinvesselsofdifferingsizes,shapes,andconfigurations.

UsingthepatentedSonicIntelligenceecho-processingsoftwaretomeasurelevel,space,distance,volume,oraverage/differential,theLU10providessuperiorreliabilityandaccuratemeasurementinvesselsupto60metersinheight(200ft).Furthermore,transducerscanbemountedupto365meters(1200ft)fromthemonitor.Readingsaredisplayedinuser-selectablelinearengineeringunitsonthebacklitLCD.

KeybenefitsconnectiontoaDCSorPLCusingSiemensMilltronicsSmart-Linx®interfacemodulesforremotetwo-waycommunicationandfullparameteraccess5ten-point,long-rangelevelmonitoringautomaticlevel-to-volumeconversionforstandardorcustomtankshapesDolphinPluscompatibleeasytoinstall,easytoprogramwithremovableinfraredkeypadtenmAoutputsareavailablethroughexternalmoduleSITRANSLUAOtwentyrelaysforalarmsareavailablethroughexternalmoduleSITRANSLUSAM

Keyapplications

chemicalstorage

liquidstorage

bulksolidsstorage(sugar,flourbins,grains,cereals)

plasticpellets

tankfarms

SITRANSLU10monitoringcoalbunkers

HydroRanger200HydroRanger200isalevelcontrollerforuptosixpumps,andprovidescontrol,differentialcontrol,andopenchannelflowmonitoring.

Forwaterauthorities,municipalwater,andwastewaterplants,HydroRanger200isaneconomical,low-maintenancesolutiondeliveringcontrolefficiencyandproductivityneededtomeettoday’sexactingstandards.

HydroRanger200usesprovencontinuousultrasonicechorangingtechnologytomonitorwaterandwastewaterofanyconsistencyupto15meters(50ft)indepth.Achievableresolutionis0.1%withaccuracyto0.25%ofrange.Unlikecontactingdevices,HydroRanger200isimmunetoproblemscausedbysuspendedsolids,harshcorrosives,greaseorsiltintheeffluent,reducingdowntime.

Keybenefitssingleordual-pointmonitoringdigitalcommunicationswithbuilt-inModbusRTUviaRS-485SIMATICPDMcompatible,allowingforPCconfigurationandset-up.SonicIntelligenceadvancedecho-processingsoftwareprovidesincreasedreadingreliabilitywallorpanelmountingversions

sixrelaysonboardasstandardmonitorswetwells,weirs,andflumescompatiblewithSmartLinxsystemanti-greaseringfunctiondifferentialamplifiertransceiverforcommonmodenoiserejectionandimprovedsignal-to-noiseratioMCERTSapprovedforopenchannelflow

Keyapplications

wetwells flumes/weirs barscreencontrol

EchomaxTransducersEchomaxtransducersfireultrasonicpulsesandmeasurethereturnechoestodeterminethedistancefromthetransducertothematerial,whetheritbeawiderangeofliquidsorbulksolidsapplications.Designsareavailablewithdifferentmeasuringranges,processconnections,andambienttemperaturespecifications.Thetransducersaresuitableforuseinmanyapplicationsfromthebenigncleanwaterfacilitiestotheaggressivechemicalplantsordustygrainapplications.

Toselectthepropertransducerfortheapplication,chooseaccordingtoapplicationrequirementsthatincludedistance,temperature,andvesselconfiguration.Thechartbelowindicateswhichtransducersaresuitablefortheapplications.

XRS-5EchomaxXRS-5ultrasonictransducerprovidesreliable,continuousnon-contactinglevelmonitoringofliquidsandslurriesinnarrowliftstations/wetwells,flumes,weirs,andfilterbeds.Withabeamangleofjust10°andaCSMrubberface,ithasameasuringrangefrom0.3to8meters(1to26ft).Advancedechoprocessingensuresreliabledataeveninconditionswithobstructions,turbulence,andfoam.

Thepre-molded,hermeticallysealedrubberfaceandthePVDFenclosurearedesignedformaximumresistancetomethane,saltwater,caustics,andharshchemicalscommontowastewaterinstallations.With

anIP68degreeofprotection,thisruggedsensorisfullysubmersibleintheeventoffloodconditions.Iffullsubmergenceispossibleintheapplication,useasubmergenceshieldtomaintainahighlevelreadingoutputduringsubmergedconditions.

Keybenefitsbasicsystemforhigh/lowalarmordualpumpcontrollow-costtransducercompatiblewithafullrangeofSiemensMilltronicstransceiversconnectstoadvancedcontrolsystemswithcommunications,telemetry,andSCADAintegrationcapabilitieschemicallyresistantPVDFcopolymerenclosureandCSMrubberfacemeasuringrange:eightmetersformeasurementofliquidsandslurriesfullysubmersible:IP68degreeofprotectioneasyinstallationwith1"NPTor1"BSPconnection

Monitoringlevelinsewagewetwell

XPS/XCTSeries

EchomaxXPS/XCTtransducersmeasurelevelinawiderangeofliquidsandsolids.Thetransducerscanbefullyimmersed,areresistanttosteamandcorrosivechemicals,andcanbeinstalledwithoutflanges.

TheXPSseriesoffersversionsforvariousmeasuringrangesupto40meters(130ft),anduptoamaximumtemperatureof95°C(203°F).TwomodelshaveFMClass1,Div.1approvalsforapplicationswithameasuringrangeuptofifteenmeters(50ft).

TheXCTseriescanbeusedinapplicationsathighertemperaturestomeasureleveluptoadistanceoftwelvemeters(40ft)andatamaximumtemperatureof145°C(293°F).

Duringoperation,Echomaxtransducersemitacousticpulsesinanarrowbeam,sotheyareidealtransducersfordustyapplicationsandforthosewithalotofobstructions.

Keybenefitsintegraltemperaturecompensationlowringingeffectreducesblankingdistanceself-cleaningandlowmaintenanceconnectusingonlytwowires

XPS-15measuringaggregate XPS-30smeasuringminingsilos

chemicallyresistantPVDFenclosureCSA,FM,ATEXandotherglobalapprovalshermeticallysealed

XLTSeriesEchomaxXLTtransducersoperateinawiderangeofbulksolids.UsingaSiemensMilltronicscontroller,theymeasurefrom0.9to60meters(1.8to200ft)inconditiontemperaturesupto150°C(300°F).Abeamangleofjust5°providesaccuratereadingsindeep,narrowtanks.

Withitshighlydevelopedsignalsensitivity,theXLTtransduceroperatesinavarietyofdifficultapplicationsincludinglimestone,cementclinker,andhotstone.Allmodelshaveasealedaluminumfacetowithstandharshestenvironments,andtemperaturevariationsareautomaticallycompensatedforbytheintegraltemperaturesensor.

Keybenefitssealedaluminumfaceintegraltemperaturesensorself-cleaningandlowmaintenancetwo-wireconnection

easy-to-install1”threadedconnection

ST-HST-Htransducersmeasurelevelinchemicalstorageandliquidtanks.ThenarrowdesignoftheST-Hallowsthetransducertobemountedona2"standpipe.Whenmountedcorrectly,itiscompletelyprotectedfromtheprocess,andcanevenbeusedinharsh,corrosiveenvironments.

Keybenefitscanbemountedona2"standpipeimmunetocorrosiveandharshenvironmentseasytoinstallintegraltemperaturesensor

ST-Hmonitoringasmallammoniatank

Conclusion

TheSiemensMilltronicsultrasonicinstrumentsoffercustomersathoroughlevelmeasurementsolution,regardlessofapplication.Fromsmallfoodtankstoten-storeysilos,ultrasonicmeasurementisreliableandcost-effective.Itremainsavibrantmeasurementpartner,alongwithagrowingnumberoftechnologiesofferedbySiemens.Oncethecenteroftheindustry,itisnowjoinedbyradar,frequencybasedcapacitance,andTDRtoofferafullcomplementoflevelapplicationsolutions.LevelmeasurementinturnisanintegralcomponentoftheSiemensTotallyIntegratedSolutionsapproachtocustomerrequirementsforprocessinstruments,promotingaunifiedinstrumentationstrategy.Flowmeters,valvepositioners,temperaturetransmitters,pressuretransmitters,andgasanalyzersopenuppossibilitiesforapplicationsolutionsotherthanthoserequiringultrasoniclevelmeasurement.

ThisfullarmamentofinstrumentsandtechnologiesisthestrengthofwhatSiemenscanofferitscustomers,andultrasonicsbeatsstronglyatitscore.Thetechnologyhasbeenhardatworkforseveraldecadesandshowslittlesignoflosingitspopularity.Industrialdevelopmentslikedigitalcommunications,trending,datalogging,andsoftwareconfigurationpackageskeepitcurrentandviable,alongsidethewholeoftheinstrumentationcatalog.

SiemensMilltronicsisdeterminedtodevelopultrasonictechnologytoitsutmostcapacity,andrecentproductsliketheSITRANSLUT400illustratethedeploymentofthetechnologytoitsmaximumbenefitbycombiningthebestoftheoldwiththebestofthenew.

ThesimplicityandprecisionoftheSITRANSLUT400exemplifieshowultrasonictechnologyisstillaviableandvibrantplayerinthelevelmeasurementfield.Whileothertechnologieslikeradar,capacitance,andTDRhavetheirplace,ultrasonicsremainsacost-effectiveworkhorsethatoffersreliableandlongtermservice.Whencoupledwiththelatestadvancesincommunicationsandsoftwareconfiguration,ultrasonicinstrumentationremainsmadeofsternerstuffandasignificantplayeronthelevelmeasurementstage.

1TinaTurner,SimplytheBest.1989(originallydonebyBonnieTyler,1988).

2SiemensMilltronicshasinstalledoveramilliontotalapplications,combiningalltechnologies,includingultrasonics,radar,capacitance,andmechanicallevelmeasurement.Allofthisexpertiseisincorporatedineveryproductdesignedandproduced.3EthyleneTetrafluoroethylene4PolyvinylideneFlouride5Modulesforpopularindustrialbusescanbefactoryinstalledoraddedlatertomeetchangingneeds.Noexternalgatewayisrequired,reducinghardwareandcablingcosts.

GlossaryEntriesinthisglossaryarefromtheOperationofMunicipalWastewaterTreatmentPlantstextbook,fromtheIEEEdefinitionbook,andfromthecontributionsprovidedbySiemensMilltronicsProcessInstrumentsproductandapplicationspecialists.

Accuracy Theabsolutenearnesstothetruth.Inphysicalmeasurements,itisthedegreeofagreementbetweenthequantitymeasuredandtheactualquantity.

Aeration 1)Thebringingaboutofintimatecontactbetweenairandaliquidbyoneormoreofthefollowingmethods:a)sprayingtheliquidintheairb)bubblingairthroughtheliquidc)agitatingtheliquidtopromotesurfaceabsorptionofair.

2)Thesupplyingoftheairtoconfinedspacesundernappes,downstreamfromgatesinconduits,andsoon,torelievelowpressuresandtoreplenishairentrainedandremovedfromsuchconfinedspacesbyflowingwater.

3)Reliefoftheeffectsofcavitationbyadmittingairtotheaffectedsection.

AerationTank Atankinwhichwastewaterorotherliquidisaerated.

AerobicDigestion

Thebreakdownofsuspendedanddissolvedorganicmatterinthepresenceofdissolvedoxygen.Anextensionoftheactivated-sludgeprocess,wastesludgeisstoredinanaeratedtankwhereaerobicmicro-organismsbreakdownthematerial.

Agitator Mechanicalapparatusformixingoraerating.Adeviceforcreatingturbulence.

Algorithm Aprescribedsetofwell-definedrulesorprocessesforthesolutionofaprobleminafinitenumberofsteps.

Allen-Bradley®RIOorAB®Rio

Allen-BradleyRIOprotocolisanoldprotocolforcommunicatingtoremoteI/O.ItisonlyusedbyAllen-BradleyPLCs.

Alum,Aluminum

Usedasacoagulantinfiltration.Dissolvedinwater,ithydrolysesintoAl(OH)2Sulfateandsulfuricacid(H2SO4).Toprecipitatethehydroxide,asneededfor[Al2(SO4)3•18H2O]coagulation,thewatermustbealkaline.

Ambient Generallyreferstotheprevailingdynamicenvironmentalconditionsinagivenarea.

AmbientTemperature

Thetemperatureofthesurroundingairthatcomesincontactwiththeequipment.

AnaerobicDigestion

Thedegradationofconcentratedwastewatersolids,duringwhichanaerobicbacteriabreakdowntheorganicmaterialintoinertsolids,water,carbondioxide,andmethane.

AnalogSignal Asignalwherethevaluecanbeinarangeofvalues(example:from4mAto20mA).

Antenna Anaerialwhichsendsoutandreceivesasignalinaspecificdirection.Therearefourbasictypesofantennainradarlevelmeasurement.SeeHorn,Parabolic,Rod,andWaveguide.

Attenuation Atermusedtodenoteadecreaseinsignalmagnitudeintransmissionfromonepointtoanother.Attenuationmaybeexpressedasascalarratiooftheinputmagnitudetotheoutputmagnitudeorindecibels.

AutoFalse-Echo

Suppression

AtechniqueusedtoadjustthelevelofaTVTcurvetoavoidthereadingoffalseechoes.(SeeTVT).

AutoFalse-Echo

SuppressionDistance

DefinestheendpointoftheTVTdistance(SeeTVT).Thisisusedinconjunctionwithautofalse-echosuppression.

AutomaticSampling

Collectingofsamplesofprescribedvolumeoveradefinedtimeperiodbyanapparatusdesignedtooperateremotelywithoutdirectmanualcontrol.Seecompositesample.

AverageFlow Arithmeticaverageofflowsmeasuredatagivenpoint.

AverageVelocity

Theaveragevelocityofastreamflowinginachannelorconduitatagivencrosssectionorinagivenreach.Itisequaltothedischargedividedbythecross-sectionalareaofthesectionortheaveragecross-sectionalareaofthereach.Alsocalledmeanvelocity.

BarScreen Ascreencomposedofparallelbars,eitherverticalorinclined,placedinawaterwaytocatchdebris.Thescreeningsarerakedfromiteithermanuallyorautomatically.Alsocalledbarrack,rack.

BeamAngle Anglediametricallysubtendedbytheone-halfpowerlimits(-3dB)ofthesoundbeam.

BeamSpreading

Thedivergenceofabeamasittravelsthroughamedium.(http://www.ndt.net/article/az/ut_idx.htm)

Bias InSiemenslevelequipment,thereisaconfidencebiasvalueaddedindBtotheshortshotconfidencevalue.Thisisforcomparisononly.Itallowstheshortdistancetobechosenoverthelongshotdistancewiththesameconfidencevalue.PresetMilltronicsequipmentto20dB.

Biosolids Theorganicproductofmunicipalwastewatertreatmentthatcanbebeneficiallyused.

Blanking Zoneextendingdownwardfromthetransducerfaceinwhichitisreceived.

Bus Network.

BypassPipe Apipethatismountedperpendiculartoavesselwallandisopentothevesselatthetopandbottom.Thisistypicallyusedonvesselsthathavealotofturbulenceorfoam.Thebypasspipeprovidesacalmliquidsurfacelevelequaltothelevelinthevessel.

Cavitation 1)Theaction,resultingfromforcingaflowstreamtochangedirection,inwhichreducedinternalpressurecausesdissolvedgasestoexpand,creatingnegativepressure.Cavitationfrequentlycausespittingofthehydraulicstructureaffected.

2)Theformationofacavitybetweenthedownstreamsurfaceofamovingbody(forexample,thebladeofapropeller)andaliquidnormallyincontactwithit.

3)Describingtheactionofanoperatingcentrifugalpumpwhenitisattemptingtodischargemorewaterthansuctioncanprovide.

CentrifugalPump

Apumpconsistingofanimpellerfixedonarotatingshaftandenclosedinacasinghavinganinletandadischargeconnection.Therotatingimpellercreatespressureintheliquidbythevelocityderivedfromcentrifugalforce.

cfs(cuft./sec.) Therateofflowofamaterialincubicfeetpersecond;usedformeasurementofwater,wastewater,orgas;equals2.832x10-2m3/s.

Chlorination Theapplicationofchlorineorchlorinecompoundstowaterorwastewater,generallyforthepurposeofdisinfection,butfrequentlyforchemicaloxidationandodorcontrol.

Chlorinator Anymeteringdeviceusedtoaddchlorinetowaterorwastewater.

ChlorineContact

Chamber

Adetentionbasinprovidedtodiffusechlorinethroughwaterorwastewaterandtoprovideadequatecontacttimefordisinfection.Alsocalledachlorinationchamberorchlorinationbasin.

Clarification Anyprocessorcombinationofprocesseswhoseprimarypurposeistoreducetheconcentrationofsuspendedmatterinaliquid;formerlyusedasasynonymforsettlingorsedimentation.Inrecentyears,thelattertermsarepreferablewhendescribingsettlingprocesses.

Clarifier Anylargecircularorrectangularsedimentationtankusedtoremovesettleablesolidsinwaterorwastewater.Aspecialtypeofclarifier,calledanupflowclarifier,usesflotationratherthansedimentationtoremovesolids.

CollectionSystem

Inwastewater,asystemofconduits,generallyundergroundpipes,thatreceivesandconveyssanitarywastewaterorstormwater;inwatersupply,asystemofconduitsorcanalsusedtocaptureawatersupplyandconveyittoacommonpoint.

CombinedSewer

Asewerintendedtoreceivebothwastewaterandstormorsurfacewater.

CONF. CONF.istheconfidenceofsignalvaluegeneratedbythecomputer.Itisbasedonalloftheechoprocessingalgorithms.ItcanbereadinRun(key#8)andprogrammodeP805.

Confidence Describesthequalityofanecho.Theechoconfidenceisbasedonhowwellthetransducerismountedandaimed,andthenoisefloorassociatedwiththeechoprofile.Transceiversdisplayboththeshortandlongechoconfidence.IfanechoisbelowaspecificconfidencethresholditisignoredbytheSonicIntelligence®softwareroutines.

ConfidenceThreshold

Thisistheminimumconfidencevalueofanechotoberecognizedasavalidecho(Parameter805).

DaisyChained Connectedinseries,oneaftertheother.Cableisconnectedtothefirstdevice,thencomesoutofthefirstdeviceandisconnectedtotheseconddeviceandsoon.

Damping Termappliedtotheperformanceofaninstrumenttodenotethemannerinwhichthemeasurementsettlestoitssteadyindicationafterachangeinthevalueofthelevel.

dB(decibel) Aunitusedtomeasurethelevelofsound.

Dechlorination Thepartialorcompletereductionofresidualchlorinebyanychemicalorphysicalprocess.Sulfurdioxideisfrequentlyusedforthispurpose.

Defoamer Amaterialhavinglowcompatibilitywithfoamandalowsurfacetension.Defoamersareusedtocontrol,prevent,ordestroyvarioustypesoffoam,themostwidelyusedbeingsiliconedefoamers.Adropletofsiliconedefoamercontactingabubbleoffoamwillcausethebubbletoundergoalocalanddrasticreductioninfilmstrength,therebybreakingthefilm.Unchanged,thedefoamercontinuestocontactotherbubbles,thusbreakingupthefoam.Avaluablepropertyofmostdefoamersistheireffectivenessinextremelylowconcentration.Inadditiontosilicones,defoamersforspecialpurposesarebasedonpolyamides,vegetableoils,andstearicacid.

DeviceDescription

AprogramfilewrittenintheHARTorPROFIBUSDeviceDescriptionLanguage

(DD) (DDL)thatcontainsanelectronicdescriptionofallofadevice’sparametersandfunctionsneededbyahostapplicationtocommunicatewiththedevice.

DeviceNetTM Aprotocoldevelopedbyagroupofcompaniesasanopenstandard,usedtoestablishmaster-slave/client-servercommunicationsbetweenintelligentdevices.ItisbasedontheCAN(ControlAreaNetwork)protocolandisdesignedforconnectingupintelligentdevicessuchaslimitswitchesandphoto-electricsensors.Seewww.odva.org.

Dewater Toextractaportionofthewaterpresentinasludgeorslurry.

DifferentialFrequency

ThefrequencydeterminedbycalculatingthedifferencebetweenthetransmittedandreceivedfrequencyoftheFMCWradar.

DigestedSludge

Sludgedigestedundereitheraerobicoranaerobicconditionsuntilthevolatilecontenthasbeenreducedtothepointatwhichthesolidsarerelativelynonputrescibleandinoffensive.

Digester Atankorothervesselforthestorageandanaerobicoraerobicdecompositionoforganicmatterpresentinthesludge.SeealsoAerobicDigestion.

DigitalSignal Asignalwherethevaluecaneitherbealogical1oralogical0.

DissolvedOxygen(DO)

Theoxygendissolvedinliquid,usuallyexpressedinmilligramsperlitre(mg/L)orpercentsaturation.

DomesticWastewater

Wastewaterderivedprincipallyfromdwellings,businessbuildings,institutionsandthelink.Itmayormaynotcontaingroundwater,surfacewater,orstormwater.

DopplerBeatFrequency

Thefrequencydeterminedduringtheprocessofbouncingacontinuouswaveradarsignalfromamovingtarget.

“Dumb”AnalogInput/Output

AninputoroutputcardthatdoesnothaveHARTcommunicationprotocolonit.

Echo Asignalthathasbeenreflectedwithsufficientmagnitudeanddelaytobeperceivedinsomemannerasasignaldistinctfromthatdirectlytransmitted.Echoesarefrequentlymeasuredindecibelsrelativetothedirectlytransmittedsignal.

EchoConfidence

Therecognitionofthevalidityoftheechoasindustrylevel.Ameasureofechoreliability.

EchoLockWindow

Awindowcenteredonanechoinordertolocateanddisplaytheecho’spositionandtruereading.

EchoMarker Amarkerthatpointstotheprocessedecho.

EchoProcessing

Theprocessbywhichtheradarunitdeterminestheecho.

EchoProfile Agraphicaldisplayofaprocessedecho.

EchoStrength DescribesthestrengthoftheselectedechoindBabove1mVrms.

ElectronicDevice

Description(EDD)

AnothernameforDeviceDescription(DD).SeedefinitionforDeviceDescription.

ElectronicDevice

DescriptorLanguage

(EDDL)

ThelanguagethattheDeviceDescription(DD)iswrittenin.

FalseEcho Anechocausedbytheinternalstructureofacontainer.Obstructionsandincorrectunitplacementwillreturnechoesthatdonotreflectlevel.

FigureofMerit Aquantitycharacterizingperformanceofadevice,system,ormethodinrelationorcomparisontosimilaralternatives.Engineeringfrequentlydefinesfiguresofmeritformaterialsordevicestodeterminetheirrelativeutility.

FloatSwitch Anelectricalswitchoperatedbyafloatinatankorreservoirandusuallycontrollingthemotorofapump.

Flocculant Water-solubleorganicpolyelectrolytesthatareusedaloneorinconjunctionwithinorganiccoagulants,suchasaluminumorironsalts,toagglomeratethesolidspresenttoformlarge,denseflocparticlesthatsettlerapidly.

Flocculatingtank

Atankusedfortheformationofflocbythegentleagitationofliquidsuspensions,withorwithouttheaidofchemicals.

Flotation 1)Separationofsuspendedparticles,oroilandgrease,fromsolutionbynaturallyorartificiallyraisingthemtothesurface,usuallywithair.

2)Thickeningofwasteactivatedsludgebyinjectingairintoitandintroducingthemixtureintoatankwheretheairbuoysthesludgetothesurface.

Flow 1)Themovementofastreamofwaterorotherfluidfromplacetoplace;themovementofsilt,water,sand,orothermaterial.

2)Thefluidthatisinmotion.

3)Thequantityorrateofmovementofafluiddischarge;thetotalquantitycarriedbyastream.

4)Toensureforthordischarge.

5)Theliquidoramountofliquidperunittimepassingagivenpoint.

FlowRate Thevolumeormassofagas,liquid,orsolidsmaterialthatpassesthroughacrosssectionofconduitinagiventime;measuredinsuchunitsaskilogramsperhour(kg/h),cubicmetrespersecond(m3/s),litresperday(L/d),orgallonsperday(gpd).

Flume Aprimarymeasuringdeviceusedtomeasureliquidflow(Forexample,seeParshallflume).

FMCW(Frequencymodulatedcontinuous

Indirectradarlevelmeasurementtechniqueinwhichtheradardevicemodulatesthefrequencyofthetransmittedsignal.Levelismeasuredbycalculatingthedifferencebetweenthetransmittedsignalandthereturnsignal.

Frequency Thenumberofperiodsoccurringperunittime.Frequencymaybestatedincyclespersecond.

Gain Measuresoftheabilityofacircuittoincreasethepoweroramplitudeofasignalfromtheinputtotheoutput.

GritChamber Adetentionchamberoranenlargementofasewerdesignedtoreducethevelocityofflowoftheliquidtopermittheseparationofmineral(grit)fromorganicsolidsbydifferentialsedimentation.

HART® HighwayAddressableRemoteTransducer.Anopencommunicationprotocolusedtoaddressfieldinstruments.HARTisaregisteredtrademarkofHARTCommunicationFoundation.Seewww.hartcomm.orgformoredetails.

Head Theheightofthefreesurfaceoffluidaboveanypointinahydraulicsystem;ameasureofthepressureorforceexertedbythefluid.

HeadLevel Thetermusedforthelevelofwaterinaweir.

IndustrialWastewater

Wastewaterderivedfromindustrialsourcesorprocesses.

Influent Water,wastewater,orotherliquidflowingintoareservoir,basin,treatmentplant,ortreatmentprocess

Inlet 1)Asurfaceconnectiontoadrainpipe.

2)Astructureathediversionendofaconduit.

3)Theupstreamendofanystructurethroughwhichwatermayflow.

4)Aformofconnectionbetweenthesurfaceofthegroundandadrainorsewerfortheadmissionofsurfaceorstormwater.

5)Anintake.

IntermediateFrequency

Afrequencytowhichasignalwaveisshiftedlocallyasanintermediatestepintransmissionorreception.

IntrinsicallySafe

IntrinsicSafetyisaprotectionmethod,usedforcertifyingelectricalequipmenttobeusedexplosiveatmospheres(flammablegasorcombustibledust),inwhichanysparkorthermaleffectproducedbytheequipmentisnotcapableofcausingignition.

LaminarFlow Non-turbulentflow.

LongShot Describesalengthofmeasurementbeyond1m(3ft.).

Manningformula

Aformulaforopen-channelflowpublishedbyRobertManningin1890.

Margin Thedifferencecalculatedbetweentheconfidenceandthethreshold.

MasterDevice Adeviceinamaster-slavesystemthatinitiatesalltransactionsandcommands(e.g.centralcontroller).

MasterSlaveProtocol

Communicationsysteminwhichalltransactionsareinitiatedbyamasterdeviceandarereceivedandrespondedtobyaslavedevice.

Measurement Eachtimeatransmitpulseorsetnumberofpulsesissenttothetransducer.

Microwaves Thetermfortheelectomagneticfrequenciesoccupyingtheportionoftheradiofrequencyspectrumabove1GHz.

MicrowaveFrequency

Microwaveradarbeamsrangeinfrequencybetween5.8GHzand26GHz.

Modbus® Aprotocolusedtoestablishmaster-slave/client-servercommunicationbetweenintelligentdevices.Itisatrulyopen,defactostandard,andthemostwidelyusednetworkprotocolintheindustrialmanufacturingenvironment.ModbusisaregisteredtrademarkofSchneiderElectric.Seewww.modbus.org.

Modem Adevicethattransmitsdataoveraphonelinebymodulatingthedigitalsignalsintoanalogsignalsatonesideandtransmittingthatanalogsignaloveraphoneline.Atthereceivingend,itdemodulatestheanalogsignalbackintoadigitalsignal.

MotorController

Aspecializedtypeofcontrollerwhosetypicalfunctionsperformedbyamotorcontrollerinclude:starting,accelerating,stopping,reversing,andprotectingmotors.

Multi-master Morethanonemasterdeviceonthebus.

MultipleEchoes

Echoescausedbytheparaboliceffectofradartransmissioninsideadishedtopvesselorahorizontalcylindricaltank.Thesetypesofechoessurpassthereallevelwithinatank.

Multi-slave Morethanoneslavedeviceonthebus.

Nappe Thesheetorcurtainofwateroverflowingaweirordam.Whenfreelyoverflowinganygivenstructure,ithasawell-definedupperandlowersurface.

NearBlanking Ablindzonethatiscreatedinfrontofatransducerorantennatoblocktheunitfromreadingfalseechoes.

Nozzle Alengthofpipemountedontoavesselthatsupportstheflange.

OpenChannel Anynaturalorartificialwaterconduitinwhichwaterflowswithafreesurface.

OpenChannelFlow

Flowofafluidwithitssurfaceexposedtotheatmosphere.Theconduitmaybeanopenchanneloraclosedconduitflowingpartlyfull.

Parameters Inprogramming,variablesthataregivenconstantvaluesforspecificpurposesorprocesses.

ParshallFlume AcalibrateddevicedevelopedbyRalphParshallformeasuringtheflowofliquidinanopenconduitconsistingessentiallyofacontractinglength,athroat,andanexpandinglength.AtthethroatisasilloverwhichtheflowpassesatBelanger’scriticaldepth.Theupperandlowerheadsareeachmeasuredatadefinitedistancefromthesill.Thelowerheadneednotbemeasuredunlessthesillissubmergedmorethan67%.

Peer-to-PeerProtocol

Communicationsysteminwhichalltransactionscanbeinitiatedbyanydeviceonthenetworktoanyotherdeviceonthenetwork.

Primaryeffluent

Theliquidportionofwastewaterleavingtheprimarytreatmentprocess.

PrimarySedimentation

Thefirstsettlingtankfortheremovalofsettleablesolidsthroughwhichwastewaterispassedinatreatmentworks.Sometimescalledaprimaryclarifier.

PrimarySludge Sludgeobtainedfromaprimarysedimentationtank.

PrimaryTreatment

1)Thefirstmajortreatmentinawastewatertreatmentfacility,usedforthepurposeofsedimentation.

2)Theremovalofasubstantialamountofsuspendedmatter,butlittleornocolloidalanddissolvedmatter.

3)Wastewatertreatmentprocessesusuallyconsistingofclarificationwithorwithoutchemicaltreatmenttoaccomplishsolid-liquidseparation.

ProcessDeviceManager(PDM)

AprogrammadebySiemensthatisusedtoconfigure,maintain,andtrouble-shootfielddevicesonHARTandPROFIBUSnetworks.

ProcessTemperature

Thetemperatureofthegas,vapour,orairlocatedabovethematerialbeingprocessed.

PROFIBUS Acommunicationprotocolusedtoaddressfieldinstruments.DifferenttypesincludeFMS(FieldbusMessagingSystem),DP(DecentralizedPeriphery),PA(ProcessAutomation).Seewww.profibus.comformoredetails.

Profile See“EchoProfile.”

ProgrammableLogic

Controller(PLC)

Anindustrialcomputerthatacceptsinputsfromtherealworld,runsaprogram,thengeneratesoutputstotherealworldthatisusedtocontrolprocesses.

Protocol Asetofrulesthatgoverntheexchangeofinformationbetweentwoormoredevices.

PumpingStation

1)Afacilityhousingrelativelylargepumpsandtheirappurtenances.Pumphousesistheusualtermforsheltersforsmallwaterpumps.

2)Afacilitycontainingliftpumpstofacilitatewastewatercollectionorreclaimedwaterdistribution.

PTFE AnacronymforPolytetrafluoroethylene.

Radar RadarisanacronymforRAdioDetectionAndRanging.Adevicethatradiateselectromagneticwavesandusesthereflectionofsuchwavesfromdistantobjectstodeterminetheirexistenceorposition.

Range Distancebetweenatransmitterandatarget.

RangeExtension

Thedistancebelowthezeropercentoremptypointinavessel.

Relay Anelectricaldevicethatisdesignedtointerpretinputconditionsinaprescribedmannerandafteraspecifiedconditionsaremet,torespondtocauseelectricaloperationorsimilarabruptchangeinassociatedcontrolcircuits.Themostcommonformofrelayusesacoilandsetofcontacts.Whencurrentflowsinthecoil,contactsareopenedorclosed,dependingontheirarrangement.Relaysaresaidtobenormallyclosed.

Ringing Theinherentnatureofthetransducertocontinuevibratingafterthetransmitpulsehasceased.SeeBlanking.

Sampler Adeviceusedwithorwithoutflowmeasurementtoobtainaportionofliquidforanalyticalpurposes.Maybedesignedfortakingsinglesamples(grab),compositesamples,continuoussamples,orperiodicsamples.

Scum 1)Theextraneousorforeignmatterthatrisestothesurfaceofaliquidandformsalayerorfilmthere.

2)Aresiduedepositedonacontainerorchannelatthewatersurface.

3)Amassofsolidmatterthatfloatsonthesurface.

SecondaryEffluent

1)Theliquidportionofwastewaterleavingsecondarytreatment.

2)Aneffluentthat,withsomeexceptions,containsnotmorethan30mg/Leach(ona30-dayaveragebasis)ofBOD5andsuspendedsolids.

SecondarySedimentation

Asettlingtankfollowingsecondarytreatmentdesignedtoremovebygravitypartofthesuspendedmatter.Alsocalledasecondaryclarifier.

SecondaryTreatment

1)Generally,aleveloftreatmentthatproducessecondaryeffluent.

2)Sometimesusedinterchangeablywiththeconceptofbiologicalwastewatertreatment,particularlytheactivated-sludgeprocess.Commonlyappliedtotreatmentthatconsistschieflyofclarificationfollowedbyabiologicalprocesswithseparatesludgecollectionandhandling.

Sedimentation 1)Theprocessofsubsidenceanddecompositionofsuspendedmatterorotherliquidsbygravity.Itisusuallyaccomplishedbyreducingthevelocityoftheliquidbelowthepointatwhichitcantransportthesuspendedmaterial.Alsocalledsettling.Itmaybeenhancedbycoagulationandflocculation.

2)Solid-liquidseparationresultingfromtheapplicationofanexternalforce,usuallysettlinginaclarifierundertheforceofgravity.Itcanbevariouslyclassedasdiscrete,flocculent,hindered,andzonesedimentation.

SedimentationTank

Abasinortankinwhichwastewatercontainingsettleablesolidsisretainedforremovalofthesuspendedmatterbygravity.Alsocalledasedimentationbasin,settlingbasin,settlingtank,orclarifier.

SettlingTank Atankorbasininwhichwater,wastewater,orotherliquidscontainingsettleablesolidsareretainedforasufficienttime,andinwhichthevelocityofflowissufficientlylowtoremovebygravityapartofthesuspendedmatter.

ShortShot Describesalengthofmeasurementwithin1m(3ft.).

Shot Onetransmitpulseormeasurement.

SlaveDevice Adevice(e.g.transmitterorvalve)inamaster-slavesystemthatreceivescommandsfromamasterdevice;aslavedevicecannotinitiateatransaction.

Sludge 1)Theaccumulatedsolidsseparatedfromliquidsduringthetreatmentprocessthathavenotundergoneastabilizationprocess.

2)Theremovedmaterialresultingfromchemicaltreatment,coagulation,flocculation,sedimentation,flotation,orbiologicaloxidationofwaterorwastewater.

3)Anysolidmaterialcontaininglargeamountsofentrainedwatercollectedduringwaterorwastewatertreatment.

SludgeBlanket Accumulationofsludgehydrodynamicallysuspendedwithinandenclosedbodyofwaterorwastewater.

Slurry Athickwaterymudoranysubstanceresemblingit,suchaslimeslurry.

SmartProcessInstrumentation

Microprocessor-basedinstrumentationthatcanbeprogrammed.Ithasmemory,andiscapableofperformingcalculationsandself-diagnosticsandreportingfaults,andcanbecommunicatedwithfromaremotelocation.

Stillpipe Apipethatismountedinsideavesselperpendiculartothevesselwall,andisopentothevesselatthebottom.Thisistypicallyusedonvesselsthathavealotofturbulenceorfoam.Thestillpipeprovidesacalmliquidsurfaceequaltothelevelinthevessel.

Submergence 1)Theconditionofaweirwhentheelevationofthewatersurfaceonthedownstreamsideisequaltoorhigherthanthatoftheweircrest.

2)Theratio,expressedasapercentage,oftheheightofthewatersurfacedownstreamfromaweirabovetheweircresttotheheightofthewatersurfaceupstreamabovetheweircrest.Thedistancesupstreamordownstreamfromthecrestatwhichsuchelevationsaremeasuredareimportant,buthavenotbeenstandardized.

3)Inwaterpowerengineering,theratiooftailwaterelevationtotheheadwaterelevationwhenbotharehigherthanthecrest.Theoverflowcrestofthestructureisthedatumofreference.Thedistancesupstreamordownstreamfromthecrestatwhichheadwaterandtailwaterelevationsaremeasuredareimportant,buthavenotbeenstandardized.

4)Thedepthoffloodingoverapumpsuctioninlet.

SuppressedWeir

Aweirwithoneorbothsidesflushwiththechannelapproach.Thispreventscontractionofthenappeadjacenttotheflushside.Thesuppressionmayoccurononeendorbothends.

TimedRelay Arelaywhoseopeningorclosingisdelayedforaspecifiedamountoftimeaftertheoccurrenceofatriggerevent.

Totalizer Adeviceusedtocountpulses.Typicallyusedtocountthenumberofrelayclosures.

TotallyIntegrated

Automation(TIA)

ASiemensconceptforhavingallcomponentsofanautomationsystemtiedtogetherusingadvancedcommunicationprotocolsandtotallyintegratedtogether.

Turbidity 1)Aconditioninwaterorwastewatercausedbythepresenceofsuspendedmatterandresultinginthescatteringandabsorptionoflight.

2)Anysuspendedsolidsimpartingavisiblehazeorcloudinesstowaterthatcanberemovedbyfiltration.

3)Ananalyticalquantityusuallyreportedinturbidityunitsdeterminedbymeasurementsoflightscattering.

Turbulence 1)Thefluidpropertythatischaracterizedbyirregularvariationinthespeedanddirectionofmovementofindividualparticlesorelementsoftheflow.

2)Astateofflowofwaterinwhichthewaterisagitatedbycrosscurrentsandeddies,asopposedtolaminar,streamline,orviscousflow.

TVT(timevarying

threshold)

Atime-varyingcurvethatdeterminesthethresholdlevelatwhichtheechoisprocessed.

U,V,W,X,Y,Z

Ullage Amountofspaceleftinavesselinorderforittobefilled.Asopposedtothevolumeofmaterialinavessel.

WorksCitedBoyes,Wait.“TheChangingStateoftheArtofLevelmeasurement,”FlowControlMagazine,February1999.

Carlson,Al.“OpenChannelFlowmetering,”June1998.

Carlson,Al.“TheRightTransducerfortheJob,”June1999.

Crabtree,Mick.PressureandLevel,CrownPublications(Pty)Ltd.,1998,pg39–48.

Duncan,Doug.“UltrasonicSensors:Nowanevenbetterchoiceforsolidmaterialleveldetection,”Instrumentation&ControlSystems.November1998.

Evans,Jack.“Ultrasonicscomesofageforsolidsandliquids,”inTech.April1997,pg39–42.

Felton,Bob.“Levelmeasurement:AncientChore,moderntools,”InTech,August2001.

Grant,DouglasM.andBrianD.Dawson.IscoOpenChannelFlowMeasurementHandbook.FifthEdition,ISCOInc.,1997.

Hughes,ThomasA.LevelMeasurementandControl,ISAPress,2002.

Li,Gordon.“AdvancedCircuitryImprovesSignal-to-NoiseRatio,”2003.

Massa,Frank.“Somepersonalrecollectionsofearlyexperiencesonthenewfrontierofelectroacousticsduringthelate1920sandearly1930s,”TheJournaloftheAcousticalSocietyofAmerica.April1985.pg1296–1302.

MassaProductsCorp.“FundamentalsofElectroacoustics,”

www.massa.com/fundamentals.htm

Milligan,Stephen.“HowtoInstallUltrasonicTransducers,”2003.

Sirlty,PaulA.“AnIntroductiontoUltrasonicSensing,”Sensors,Nov.1989.

Allrightsreserved.

Noportionofthisbookmaybereproducedinanyformwithoutpermissioninwritingfromthepublisher.

FirstEdition,2006.SecondEdition,2008.ThirdEdition,2012

ISBN-10:ISBN0-9782495-0-X

ISBN-13:ISBN978-0-9782495-0-2

PrintedandboundinCanadaforSiemensMilltronicsProcessInstrumentsPeterborough,ONK9J7B2

www.siemens.com/processautomation

Understanding Ultrasonic Level Measurement - Gilson Eng

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