3 How it worksThe time it takes for the instrument’s signal to leave the antenna, travel to the product, and return to the antenna is calculated into distance.The instrument is spanned according to the distance the 100% and 0% points within the vessel are from its reference point.The measured distance can then be converted into the end user’s desired engineering unit and viewed on the head of the instrument or remote display.100%0%
4 Process conditions that affect specification of transmitters How do process conditions affect the reliability and accuracy of process level transmitters ?density (specific gravity)?dielectric constant?conductivity?temperature?pressure?vacuum?agitation?vapors and condensation?dust and build up?internal structures?
6 Radar Technology – How it works Radar is a time of flight measurement.Microwave energy is transmitted by the radar.The microwave energy is reflected off the product surfaceThe radar sensor receives the microwave energy.The time from transmitting to receiving the microwave energy is measured.The time is converted to a distance measurement and then eventually a level.
7 reduction of the antenna ringing optimization of the beam Function of an antennaSignal focusingreduction of the antenna ringingoptimization of the beamSignal amplificationfocusing of the emitted signalamplification of the receipt signalSignal orientationpoint at the product surfaceminimization of false echo reflections
8 Radar Technology – Why use it? Radar level measurementTop mountedSolids and liquids applicationsNon-contactRADAR is virtually unaffected by the following process conditions:TemperaturePressure and VacuumConductivityDielectric Constant (dK)Specific GravityVapor, Steam, Dust or Air MovementBuild up (depends on radar design)
9 Radar Technology - Choice of frequency Radar wavelength = Speed of light / frequencyl = c / f47.5mmFrequency 6.3 GHzwavelength l = 47.5 mm11.5mmFrequency 26 GHzwavelength l = 11.5 mmHigh frequency:shorter wavelengthnarrower beam anglemore focused signalability to measure smaller vesselswith more flexible mountingLow frequency:longer wavelengthwider beam angleless focused signalability to measure in vessels withdifficult application variables
10 Radar Technology – Focusing of Frequency Comparison of horn diameters that produce the same beam angle(A shorter wavelength means a smaller antenna for the same beam angle)Focusing at 6.3 GHz:Horn size Beam angle3“ 38°4“ 33°6" 21°10“ 15°Focusing at 26 GHz:Horn size Beam angle1.5" 22°2“ 18°3“ 10°4“ 8°6.3 GHz26 GHz5 GHz10 GHz15 GHz20 GHz25 GHz30 GHzFrequency
11 Major Factors in Specifying a Radar - Frequency Choosing a frequency depends on:Mounting optionsCustomer’s 100% pointVessel dimensions – proximity of connection to sidewallThe presence of foamAgitated product surfacesVapor compositionVessel internal structuresDielectric constant (dK)
12 Radar Technology – Choosing a frequency No single frequency is ideally suited for every radar level application.Low Frequency – 6.3 GHz – C-bandBetter Performance with:Heavy AgitationSevere Build-upFoamSteamDustMistDish bottom vesselsTypical accuracy: +/- 10mmHigh Frequency – 26 GHz – K-bandSmall Process ConnectionsVery little “near zone”Recessed in nozzlesLess susceptible to false echoesReduced antenna sizePerfect for small vesselsAble to measure lower dKproducts without using astilling well.Typical accuracy +/- 3-5mm
14 Guided Wave Radar Measurement Guided Wave Radar level measurementTime of FlightTop mountedSolids and liquids applicationsContact MeasurementGUIDED WAVE RADAR is virtually unaffected by the following process conditions:TemperaturePressure and VacuumConductivityDielectric Constant (dK)Specific GravityVapor, Steam, or Dust Air MovementBuild up (depends on type of build up)Foam
15 Principle of Operation A microwave pulse (2 GHz) is guided along a cable or rod in a 20” diameter or inside a coaxial system.The pulse is then reflected from the solid or liquid, back to the head of the unit.The travel time of the pulse is measured and then converted to distance.
16 Installation into the vessel Application ExamplesInstallation into the vesselInstallation in bridles without worry of build-up or interference from side leg connectionsIdeal for replacement of displacers
20 Ultrasonic Level Measurement Time of FlightTop mountedSolids and liquids applicationsNon-contactULTRASONIC is virtually unaffected by the following process conditions:Change is product density (spg)Change in dielectric constant (dk)
21 Ultrasonic Level Measurement – How it works Time of Flight TechnologyShort ultrasonic impulses emitted from transducerBursts are created from electrical energy applied to piezeo electric crystal inside the transducerThe transducer creates sound waves (mechanical energy)With longer measuring ranges a lower frequency and higher amplitude are needed to produce sound waves that can travel fartherThe longer the measuring range the larger the transducer must be
22 Ultrasonic Level Technology – Advantages Can be mounted in plastic stilling wellsNarrow beam angles minimize effect of obstructionsSwivel flange available for applications with angles of reposeFamiliar technology throughout the industry, therefore, often a trusted technology throughout the industryCost-effective
23 Ultrasonic Level Technology – When to use it Vessels with products whose characteristics remain constantWaterBulk solidsStorage VesselsWhere repeatability is not criticalTypical Accuracy +/ mm