Ultrasonic Measurement prosonic FDU 80…86

1 TechnicalInformationTI 189F/00/enOperating Instructions015081-1007 ApplicationProsonic FDU is a series of nineultrasonic sensors with differentmeasuring ranges for continuous, non-contact Measurement of level and flow. FDU 80, 80 FLiquids: 5 m (16 ft)Solids: 2 m ( ft) FDU 81, 81 FLiquids: 10 m (32 ft)Solids: 5 m (16 ft) FDU 82 Liquids: 20 m (65 ft)Solids: 10 m (32 ft) FDU 83 Liquids: 25 m (82 ft)Solids: 15 m (49 ft) FDU 84 Solids: 25 m (82 ft) FDU 85 Solids: 45 m (147 ft) FDU 86 Solids: 70 m (230 ft)The material to be measured can beaggressive liquids such as alkali or acid,or powdery and clumpy solids such asgrain, coal, ore and and Benefits Complete sensor programme fornon-contact, continuous measurementof level and flow For use in flumes, weirs, tanks andsilos Insensitive to dirt and build-up Optional integrated heating to protectagainst a build up of ice on the sensor Wide range of mountings using flangeor thread(with slip-on flange for flush mountingof the sensor)

2 Weather resistant and safe againstsubmersion (IP 68) Integrated temperature sensorUltrasonic Measurementprosonic FDU for non-contact, continuousmeasurement of level and for use in explosion hazardous +EndressThe Power of Know HowPlease note: From January 2008, the sensors are only available as spare SystemMeasuring SystemThe complete measuring system consistsof the prosonic FDU 80, 80 F, 81, 81 F, 82,83, 84, 85 or 86 Ultrasonic sensor the transmitter prosonic FMU 860: 1-channel versionfor level Measurement or prosonic FMU 861: 1-channel versionfor flow Measurement or levelmeasurement or prosonic FMU 862:2-channel FDU 86 can be selected andoperated by FMU 86x transmitters withsoftware version AccessoriesThe accessories (see pages 9 and 10)ensure that the sensors can be adaptedto special process conditions.

3 Alignment unit FAU 40 for the sensor All-weather protective cover Mounting frame Wall bracket Sensor flanges ( FAU 80) External temperature sensor FMT 131 A separate power supply unit isavailable for heated emitter in the sensor is excitedelectrically and sends an ultrasonicpulse in the direction of the surface ofthe product which partially reflects thepulse. This echo is detected by the samesensor, now acting as a directionalmicrophone, and then converted backinto an electrical signal. The timebetween transmission and reception ofthe pulse (the sonic run time) is directlyproportional to the distance between thesensor and the product surface.

4 Thisdistance is determined by the velocity ofsound c and the run time t using theformula:Blocking DistanceDue to the ringing time of the sensor,there is a zone immediately below thesensor in which returning echoescannot be detected. This so-calledblocking distance BD determines theminimum distance between the sensordiaphragm and the maximum level inthe silo. If the minimum distance is notmaintained, the level will not bemeasured 80F with flangeFAU 80 FDUThe prosonic transmitters have an input for theconnection of a separate limit withalignment unitFAU principle ofFDU ultrasonicsensorsBD Blocking distanceD Distance fromsensorto surface ofmaterialLHeight in silo(Level)F Maximum level(100%, Full)E Zero point ofmeasurement(0%, Empty)D=ct2 PlanningRecommendationsMaximum Measuring RangeThe correct sensor for your particularapplication depends on the process andambient conditions.

5 When selecting thesensor, take into account that themaximum measuring range of theindividual sensor is determined by theattenuation of the Ultrasonic pulse by theair as well as by the reflectingcharacteristics of the product the level of background noise ( filling) and the mounting point alsocan affect RequirementsOptimum conditions in tanks or silos areachieved if the lower edge of the sensor is belowthe silo roof the detection zone does not includeany internal fixtures or the filling curtain the surface of the solid is hard andcoarse-grained the surface of the liquid is calm and novapour is formed operation is under normal atmosphericpressure the vessel is not being filled than optimum conditions reducethe measuring range of the the RangeThe diagram shows ideal attenuationcurves for the

6 FDU sensors: Check the factors affecting yourmeasurement in the table right. Add up their attenuation values. Take this sum and find the point whereit intersects with the range limit line ofthe sensor you are usingFactorsAttenuation(dB)Temperature layering airtemperature difference betweensensor and surface of materialup to 20 C (68 F)up to 40 C (104 F)up to 80 C (176 F)up to 150 C (302 F) curtainoutside detection zonesmall amounts in detection zonelarge amounts in detection amountshigh of solidhard, coarse ( grit)soft( peat, dust-covered clinker) of liquidcalmripplesstrong turbulence( agitator blades)

7 Contact Endress+HauserSensor installationlower edge free in siloon collar, lower edge slanteddepending on diameter/length ratioon collar, lower edge horizontaldepending on diameter/length 85 FDU 86 FDU 83 FDU 84 FDU 82 FDU 81, 81 FFDU 80, 80 FEcho attenuation as afunction of range forvarious sensors (idealreflection andatmospheric conditions)MeasuringrangemAttenuation dBExample for calculating range: Silo with gritapprox. 40 dB Little contentapprox. 5 dB Little dustapprox. 5 dBGives an attenuation of 50 FDU 82 sensor measures up to 8 munder these m = ft1 ft = mInstallationDetection Limits and InterferenceSignalsIf internal fixtures are present in the tank,then careful alignment of the sensor iscritical in order to keep the interferenceecheos as low as possible.

8 Theultrasonic pulse should travelunimpeded to the surface of thematerial. The signal leaves the sensor asa narrow beamwhich widens as thedistance increases. Every objekt withinthis beam gives rise to an echo which isthen received by the radius of the beam can be easilyestimated by using the 3 dB A constant temperature and soundvelocity within the measuring pathenable a high degree of accuracy tobe achieved. The effects of largetemperature variations within themeasuring path and changing gasmixtures must be calculated and theProsonic programmed accordingly.

9 With liquids having a high partialpressure, the gas composition mustbe determined to see if it Limits The sensors may not be used tomeasure aliphatic hydrocarbons(not applicable to FDU 80 F / FDU 81 F).Estimation of the Detection Limits ofthe DetectorPlease note: Edges, internal fixtures, etc. within thesound cone are of greatest importancein the first third of the range as theenergy of the beam is highlyconcentrated. The energy in the last third of therange is distributed over a larger area,so that internal structures and edgesare not as rL 3 dB beam angleL length of beam(calculated from range ofsensor)r radius of beamr=tan2L Liquids LrFDU 80, 80 F8 5 m(16 ft)( ft)FDU 81, 81 F8 10 m(32 ft)( ft)FDU 828 20 m65 ft)( ft)FDU 834 25 m(82 ft)( ft)SolidsFDU 808 2 m( ft)( ft)FDU 818 5 m(16 ft)( ft)FDU 828 10 m(32 ft)( ft)FDU 834 15 m0,52 m(49 ft)( ft)FDU 845 25 m(82 ft)( ft)FDU 855 45 m(147 ft)( ft)FDU 866 70 m(230 ft)

10 ( ft)Guidelines when Mounting Check that the maximum level heightdoes not come within the blockingdistance of the sensor(see page 11, Technical Data ). If possible, the face of the sensorshould lie parallel to the surface of theproduct. The PE or PTFE coating on thediaphragm of the FDU 84, 85 and 86 isan integral part of the measuringsystem and must not be damagedduring installation. Do not damage the funnel of the FDU86 when mounting. The connecting cable of the FDUsensor is not designed as a supportingcable. Do not use it as a suspensionwire.