Mikroimpuls-Level Measurement levelflex FMP 232 E/332 E

1 TechnicalInformationTI 278F/00/enApplicationLevelflex FMP 232 E/332 E is a compactlevel transmitter for bulk solidapplications. It has a galvanicallyisolated current output, optionally withHART communication signal. The probeis mounted in the top of the silo andmeasures the time that a high frequencyimpulse requires to cover the distancefrom the process connection to theproduct surface and back measures independent of thephysical properties of the bulk solid, moisture content, grain size,pressure and temperature. It is suitablefor all bulk solids with grain size up to20 mm and a dielectric constant of greater, sand, cement, limestone,agricultural products, flour, animal feed,fly-ash or the dielectric constant is not known,then the density of the material can beused as a good guide to estimate has shown thatmeasurement can easily be carried outwith densities greater than 500g/l or if ithas a high moisture content.

2 The DKshould be measured or a pilot trialcarried out on very dry materials or if thedensity is below 500 and Benefits Simple commisisioning due to factoryadjustment on-site calibration isseldom required: mount and measure Safe Measurement no problems withpneumatic filling or extremely dustyconditions Measurement independent of productproperties (moisture content, changeof product), silo construction(materials, geometry) and operatingconditions (dust, build-up) Remote operation through HART communication protocolMikroimpuls-Level Measurementlevelflex FMP 232 E/332 ELevel Measurement of bulk solidsVersion for use in hazardous areasleft: levelflex FMP 332 Ewith threaded flange(assessory), heavy duty8 mm rope and ballastweightright: levelflex FMP 232 Ewith threadedconncetion, 4 mm ropeand ballast weightHauser+EndressThe Power of Know HowMeasurement PrincipleLevelflex is a downward-looking time-of-flight system, which measuresthe distance from the probe mounting(top of silo) to the material level.

3 Anelectrical impulse is launched andguided down the probe rope, whichacts as a surface wave the surface wave meets adiscontinuity in the surroundingmedium, a sudden change indielectric constant, it is partiallyreflected. The reflected impulse travelsback up the probe to the pulse samplerwhere it is detected and point along the probe is sampledfor its pulse reflection behaviour. Theinformation accumulated over thesampling cycle is captured and passedon to the signal processing, whichidentifies the signal produced by thechange in dielectric constant at theair/product distance D to the surface of theproduct is proportional to the time offlight of the pulse t:D=c t/2,where c is the speed of the empty distance E is known tothe system, it is a simple matter tocalculate the level L1:L1 = E - DThe datum point for "E" is the top threadof the process leaves the factorypre-calibrated.

4 Zero (E) is 35 cm above the end of theballast weight or tie-down loop span (F) is 90% of E the measuring range is adjustablebetween a point 30 cm below the topof the process connection thread anda point 35 cm above the probe end forversions with ballast weight. Forversions with tie-down, the lowestmeasurable point lies 5 cm above thetop end of the tie-down loop, mm above the probe end forFMR 232E and 350 mm above theprobe end for FMR the factory adjustment these pointscorrespond to the current output values4 mA and 20 mA or digital output values0 and 100. The range and units may bere-adjusted locally at the display orremotely via the foreign system fully extended and hangingvertical in the silo, levelflex is capableof measuring at all points from the top ofthe ballast weight or tie-down loop towithin 30 cm of the mounting point to ameasured error of 1%, see mADL1reference pulselevel pulsebottom of weightor tie-down loopmeasuring cmReflection curveMeasurement prinzipleand signal processingof LevelflexFMP 232 E/332 EFactory settings.

5 E = (Zero) 35 cm abovethe probe end,F = (Span) 90 % E, butnot nearer than 30 cmto top thread of cm2 Measuring mA Current OutputVersion with active current output andlocal configuration mA HART OutputVersion with active current output andsuperimposed HART digital signal. Can be configured locally, or remotelywith a handheld terminal DXR 275. Alternatively a personal computer,Commuwin II and Commubox FXA 191can be Integration via RackbusSeveral levelflex transmitters (or otherdevices) can be linked to a supervisorybus system with a gateway ZA. HART transmitters via one FXN 672interface module each also providespower. Gateways are available for MODBUS,PROFIBUS-FMS and -DP INTERBUS,CONTROLNET etc.

6 Both on-site and remote operation mA +HART laptop + Commuwin IIvia Commubox FXA 191powerHART handheldlenft:Single measuring pointwith mA signalright:Single measuring pointwith HART outputZA 672 FXN 671mA1+FXN 671mA1+FXN 671mA1+FXN 671mA1+FXN 671mA1+PC withCommuwin IIe. g. PROFIBUS-FMSR ackbusmax. 64transmittersHART transmittersgateway ZA toMODBUS,PROFIBUS, 672powerSystem integration ofHART transmitters via aRackbus mAactiveanalogue display3 Probe SelectionProcess ConnectionLevelflex is equipped with either aBSP 1 " (G 1 " to DIN/ISO 228) or1 " - 11,5 NPT threaded connnection. The pressure and temperaturederating curves are shown in thediagram.

7 Standard adapter flanges with a threa-ded bore are available as MaterialTwo types of rope are available: stainless steel rope for standard andcorrosive applications. PA 12-coated carbon steel rope for usewith abrasive and build-up formingmediaRope Thickness and LengthTwo thicknesses 4 mm und 8 mm andcustomer specific lengths of rope ApplicationsFor standard applications an uncoatedstainless steel rope with ballast weightis DischargeIf the product tends to charge up duringhandling extremely, we recommend thata grounding chain is hung in the ForcesThe silo roof and probe rope mustwithstand the down-pull of the medium. The down-pull is dependent upon thebulk density and coefficient of frictionof the material, the size of the silo, theposition in the silo and the StrengthThe breaking strength for the standardrope (FMP 232 E) and heavy duty rope(FMP 332 E) is shown in the ropeFMP 232 KNFMP 332 KNForces on Ropes with Ballast WeightThe table below summarises thedown-pull forces and permissible ropelengths for thefree-hangingversionwith ballast weight.

8 They are based onmeasurements, calculations and experi-ence. The values for individual casesmay be significantly different. For silos less than 10 m dia. the fulllength applies to all the casesdescribed. The down-pull forces are shown toassist the user in considering on Ropes with Tie-DownDepending upon their position in thesilo, the forces on ropes with tie-downsare two to ten times greater than onropes with ballast weights. Forces increase with buried lengthand silo diameter. Both parametersare of equal importance. Allow a good safety (-1)-40-20020406080100120481216-20-40-20 020406080100120200406070usable rangeFMP 232 E/332 Epressure (bar gauge)process temperature ( C)use remote version for thisrangeusable rangecompact versionambient temperature ( C)limit for Dust-Exversionprozess temperatur ( C)left:pressure versustemperature on processconnectionright.

9 Ambient temperaturversus temperatureon process connectionMaterial4 mm uncoated4 mm coated8 mm uncoated8 mm coatedL maxpull (kN)L maxpull (kN)L maxpull (kN)L maxpull (kN)Wheat101101,4205,2207,2 Polypropylene pellets100,7100,9203,6203,6 Gravel104,510620261943 Cement10610720382039 Worst case pull-downforces as a fuction of ful-ly buried rope and mate-rial for a 12 m max = maximumprobe lenght4 Installation HintsEnvironmentThe normal operating temperature ran-ge is 20 C to +70 max. +60 C For higher ambient temperatures, theremote mount option allows the headto be positioned at a cooler locationup to 3 m away. For outdoor installation, werecommend the use of a temperature The temperature of the medium maynot exceed +120 C.

10 The effects of abrasive media can becounteracted by the choice of a coa-ted probe grain size 20 housingThe remote housing is designed for usewith high temperatures, moisture orstrong vibration wherever the sensor lenght of seperat housingFor bulk solids with a dielectric constantof less than , the maximummeasuring range decreases with thecable lenght of the separate housingaccording to the following table:Cable lenght ofseperat housingMaximummeasuring area1 m19 m2 m18 m3 m17 mMediumLevelflex measures reliably infine-grained solids as varied as cement,sand lime, flyash, aggregates, plasticpellets, and powdered materials. Forother media a guideline is a relativedielectric constant of or PositionLevelflex is top-mounted.