Ultrasonic Level Measurement DU 60 Z and DU 61 Z Sensors

Transcription

1 Technicl Informtion TI 9F//en Ultrsonic Level Mesurement DU 6 Z nd DU 6 Z Sensors Modulr design, corrosion-resistnt Approved for explosion hzrdous res DU 6 Z Mesuring rnge pprox. m DU 6 Z Mesuring rnge pprox. m Advntges of Ultrsonics Wide rnge of pplictions from liquids through pstes to bulk solids Mesurement ccurcy unffected by product properties such s density or conductivity No reclibrtion necessry on chnge of product Appliction Non-contct, continuous level mesurement in explosion hzrdous res. Mesuring rnge in liquids: DU 6 Z up to m DU 6 Z up to m depending on mesuring conditions Operting pressure p e mx. 3 br Operting temperture:...8 C Principle Sensor Fetures Resistnt to ggressive vpours nd condenstes One-piece seling fce nd diphrgm Sewter-proof housing Modulr design with slip-on flnge for ll interntionl stndrds Intrinsiclly sfe sensor cc. to ATEX II G EEx i IIC T6...T5 for connection to Nivosonic FMU 673 Z or FMU 678 Z trnsmitters Electricl isoltion of sensor circuits Degree of protection IP 68 Endress Huser The Power of Know How

2 Mesuring Principle BD FMU 673 Z V H D V H E ma ma Ultrsonic mesuring principle D = Distnce sensor product surfce BD = Blocking distnce Ultrsonic Mesurement A sensor mounted bove the product directs n ultrsonic pulse through the ir towrds the product surfce. The product surfce prtilly or fully reflects the pulse bck to the sensor. This echo is detected by the sme sensor, now cting s directionl microphone, nd converted into n electricl signl. The time between trnsmission nd reception of the pulse the run time is directly proportionl to the distnce between the sensor nd the product surfce. The distnce D is determined from the velocity of sound c nd the run time t by the formul: D = c * t/ For c = 34 m/s, run time of ms corresponds to trnsmission pth of 3.4 m nd thus to distnce of.7 m. Mesuring Rnge After the ultrsonic pulse hs been emitted the sensor requires time the ringing time to stop vibrting. Consequently there is zone immeditely below the sensor from which returning echoes cnnot be detected. This so-clled blocking distnce determines the strt of the mesuring rnge. The end of the mesuring rnge is determined by the ttenution of the ultrsonic pulse by the ir s well s by the strength of the reflection from the product surfce. Requirements The primry requirement for good ultrsonic mesurement is reflection t the product surfce: For liquids, there my be no closed, thick fom lyer on the product surfce. For bulk solids, the surfce roughness (prticle size) must exceed 3 mm or the surfce must reflect directly to the sensor.

3 Mesuring System /4 ma Min./Mx. Rckbus PC, PLC, PCS FMU 673 Z FMU 678 Z FMU 678 Z FMU 678 Z ZA V H V H ZA 67 Interfce E In ddition to the fetures listed below, the Nivosonic FMU trnsmitters cn be integrted vi the Rckbus nd ZA 67 interfce into computer control system. Nivosonic FMU 673 Z/678 Z The ultrsonic sensor is powered nd controlled by the Nivosonic FMU trnsmitter. It provides the trnsmitter with digitl informtion which is converted to level or content vlue. An integrted temperture sensor, locted behind the diphrgm, mesures the temperture of the ir bove the product. The Nivosonic FMU 673 Z/678 Z trnsmitter performs the following functions: Mesured vlue disply. Lineriztion of the vessel chrcteristic. Compenstion of temperture dependent ultrsonic run times. If necessry, suppression of spurious echoes cused by fixtures etc. within the vessel. The velocity of sound nd temperture dependence re set for ir t the fctory (c = 33.6 m/s t C nd.6 ms - / C or.7%). The vlues re progrmmble nd cn be set for other gs mixtures. Mesurement Accurcy Mesurement ccurcy is unffected by the strength of the reflected signl. The effect of pressure chnges within the operting rnge in ir or nitrogen is <.%. A constnt temperture nd velocity of sound llows error limits of < % to be ttined. The resolution of the mesurement is.7 cm for sound velocity of 34 m/s. Inhomogenous Gses If pronounced temperture or concentrtion grdient exists in the gs bove the product surfce, its effect must be estimted nd progrmmed in the Nivosonic FMU trnsmitter. For nitrogen lyers bove the product surfce the effect is % only. For liquids with high prtil pressures, e.g. benzene, check whether there is concentrtion grdient. 3

4 Plnning Mximum Mesuring Rnge The mesuring rnge depends upon: The strength of the reflection from the product surfce. The ttenution of the ultrsonic pulse within the tnk or silo. The level of bckground interference e.g. filling noise. Interference echos cused by fixtures etc. in the tnk or silo. The first two fctors re determined by the ppliction nd cnnot be directly influenced. Their effect cn, however, be estimted from the tble below. Interference echoes cn be voided by following the recommendtions in this brochure. Attenution The digrm shows idel ttenution curves for the DU 6 Z/6 Z sensors: Check the fctors ffecting your mesurement in the tble below. Shift the idel ttenution curve down by the sum of their ttenution vlues. Check your bckground noise level (in the digrm pprox. db) nd subtrct it from the theoreticl detection limit of db. The intersection of the curve nd bckground noise gives the mximum mesuring rnge see exmple. DU 6 Z DU 6 Z db Blocking distnce Echo dmping 4 6 Exmple for clculting rnge: storge tnk with oil emulsion light wves on the surfce pprox. 5 db temperture difference in tnk 4 5 C pprox. db gives n ttenution of pprox. 5 db bckground noise pprox. db The DU 6 Z sensor hs rnge of bout 8.5 m under the conditions stted. Idel ttenution curve DU 6 Z Echo ttenution s function of distnce for idel reflection nd tmosphere In mounting pipe the sensor genertes n interference signl which decreses with incresing pth 8 Interference level when sensor in mounting pipe Possible (e.g. db) bckground noise Idel ttenution curve DU 6 Z m m 5 m m Detection limit db Rnge Effects in liquid tnks Attenution db Effects in bulk solid silos Attenution db Temperture lyers Difference in ir up to C temperture between up to 4 C sensor nd product up to 6 C surfce Temperture lyers Difference in ir up to C temperture between up to 4 C sensor nd product up to 6 C surfce Filling curtin Outside detection rnge Smll mount inside detection rnge Lrge mount inside detection rnge Filling curtin Outside detection rnge Smll mount inside detection rnge Lrge mount inside detection rnge Fom Plese consult EndressHuser Dust No dust Light dust Hevy dust Attenution in db for interference effects in tnks nd silos Liquid surfce Clm Hevy wves Very turbulent (e.g. gittor bldes) Solids surfce Corse, hrd Corse, soft (e.g. pet, dust-covered clinker)

5 Recommendtions Liquid Tnks Do not instll the sensor directly bove the inflow nozzle (). Pln mounting pipes (b) such tht even in the event of overfilling, the level does not come within the blocking distnce. b Do not mesure through the filling curtin Bulk Solid Silos Direct the sensor to the centre of the outflow funnel () so tht n echo is received when the silo is empty. To ensure ccurte redings, keep wy from the sidewlls nd select the lrgest ngle possible (b) to the filling mound or outflow funnel. Avoid mesuring through the filling curtin (c). b b c b For bulk solids, nerly norml ngle of 9 incidence ensures strong echo 5

6 Internl Fittings Sensor Position If the tnk or silo contins internl fittings, correct positioning of the sensor is essentil if interference echoes re to be kept to minimum. Check tht the ultrsonic pulse rrives unhindered t the product surfce. DU 6 Z 7 m Mesuring rnge nd detection zone DU 6 Z (lines of equl ttenution) Detection zone for wek signl Ultrsonic Bem The ultrsonic pulse leves the sensor s directed bem which slowly widens s it trvels towrds the product surfce. Any object lying within the bem will produce n echo which my be received by the sensor. Edges, internl fittings etc. lying within the bem in the first third of selected mesuring rnge re most criticl since the sonic energy is still highly concentrted here nd due to the short distnce, the echoes re only wekly ttenuted: smll reflecting surfces cn cuse very strong echoes. In the lst third of the selected mesuring rnge the sonic energy is spred cross much lrger re. Here reflections from internl fittings nd edges re much less criticl. Across the bem two detection zones cn be defined: Any object within the centrl detection zone (full line in the illustrtions) will produce strong echo. Echoes from the second zone re importnt to mesurement only when the signl from the surfce of the product is reltively wek. Mesuring rnge nd detection zone DU 6 Z (lines of equl ttenution) DU 6 Z 4 m Detection zone for wek signl 4 m 8 m m m m m m m 6

7 Sensor Positioning DU 6 Z: ø min. mm DU 6 Z: ø min. 5 mm Close to the sensor the ultrsonic pulse is highly energetic. Any edges, welds or similr projections in the mounting pipe will cuse strong spurious echoes. Build-up from splshes or condenstion will lso cuse echoes. Avoid condenstion by thermlly insulting the mounting pipe. l* Avoid overhngs (must be <. mm) *l = mx. x dimeter l* No welding bed Inside edge ground Mounting Using the slip-on flnge, the sensor my be mounted: flush with the tnk top on mounting pipe. Alterntively the mounting brcket cn be used to hng the sensor from the top of the tnk or silo. Blocking Distnce The sensor must be mounted such tht the gp between it nd the mximum filling level exceeds the blocking distnce. If this criterion is not fulfilled, incorrect mesurement will result. Strong product echo: The fitting is not criticl Wek product echo: The fitting must lie outside the bem A cldding my reduce interference echoes For wek echos, cre must be tken tht reflecting edges or fittings lie outside the detection zone. Alterntively, the interfering object cn be covered by suitble cldding m m m e.g. DU 6 Z Internl Fittings The echo from the product surfce must lwys be stronger thn ny bckground noise. Check the required lterl clernce from ny fittings by using the detection zone digrms. Clddings cn be used to direct the interference echo wy from the sensor. Tnk or silo wlls with surfce roughness >.5 mm my lso cuse interference echoes. If the sensor cnnot be mounted to meet the bove conditions, the fixed trget echoes cn be suppressed by the FMU softwre see»interference Echoes«. 7

8 FMU 673 Z V H E ma ma Interference Echoes DU VH Suppression of interference echoes from fixtures: ➀ Trnsmission pulse nd signl decy ➁ Time-dependent identifiction threshold ➂ Interference echo ➃ Echo suppression by temporry increse of threshold ➄ Strong echo from product surfce Interference Signl Suppression Interference echoes from sttionry internl fittings cn be suppressed using the»fixed trget suppression«mode of the Nivosonic FMU... The detection threshold is utomticlly djusted to the echo profile so tht interference echoes re no longer registered nd processed. Spordic Echoes Wek spordic signl, no problem Spordic signl, positioning importnt Permnent signl, sensor too ner xis By creful plcement of the sensor, problems with spordic echos cn be minimised Lowest mesurble point Stirrers etc. Moving internl fittings my produce spordic echoes. If the sensor is mounted too ner the xis of the stirrer, the interference will be permnent. If the stirrer bldes re offset, position the sensor such tht the intervl between echoes is s long s possible. Interference from e.g. stirrer bldes cn be suppressed by the signl sttistic of the Nivosonic FMU 673 Z/678 Z trnsmitter. 8

9 Electricl Instlltion Sensor Connection Power is supplied by the Nivosonic FMU 673 Z/678 Z Use commercil 3-core instlltion cble Mx. line resistnce 5 Ω per core When instlling in explosion hzrdous res, observe the relevnt regultions (s. XA 9F-A) DU 6 Z DU 6 Z 3 d b d4 FMU 673 Z FMU 678 Z 879- Connection digrm Sensor Nivosonic FMU 673 Z/678 Z To Prevent Interference The following mesures re recommended to prevent interference e.g. cused by electricl or mgnetic fields in the pth of the cbling or by RFI ner to the sensor: Use screened cbling. Connect screening to the inner ground terminl of the DU 6/6 Z sensor; not to the Nivosonic FMU Connect the ground or potentil compenstion cble to the outer ground terminl of the sensor. These mesures ensure tht the sensors correspond to industril (NAMUR) nd Europen EMC Stndrds EN 58- for interference emission nd EN 58- for interference immunitiy. For generl informtion on EMC (test methods, instlltion hints) see TI 4F//e. FMU 3 Nivosonic FMU 673 Z/678 Z d b z Inputs Rckbus non-hzrdous re d4 b d hzrdous re 3 DU 6 Z DU 6 Z Connection digrm Nivosonic FMU 673 Z/678 Z u 4 u 6 8 u r r r 3 L 3 L Anlog outputs Limit switch ➀ Limit switch ➁ Power supply Current Voltge r u r u r u d b d d4 b b4 z8 d z z d4 z4 z6 d8 z8 z3 d3 d d4 L L ZA 67 /4 ma / V V 3 V Remote dilogue Level or contents mesurement Limit vlue ➀ Limit vlue ➁ Fult indiction DC supply 9

10 Technicl Dt Housing Mteril: Crstin (PBTP) Seling fce nd diphrgm: PVDF Slip-on flnge: see product structure Protection: IP 68 Weight: pprox. 4 kg Slip-On Flnge Stndrd connections to DIN, JIS or ANSI Mteril: polypropylene, pinted steel or stinless steel see pge Counterflnge on tnk DU 6 Z with ID min. mm DU 6 Z with ID min. 5 mm Ultrsonics DU 6 Z DU 6 Z Rnge: m* m* Frequency: 38 khz 3 khz Pulse frequency: 4 Hz Hz Blocking distnce:.5 m.8 m Angle of emission t 3 db: 5 8 * Under idel mesurement conditions Operting Conditions Operting pressure p e with metl slip-on flnge mx. 3 br; with polypropylene slip-on flnge mx..5 br Sttic pressure with steel flnge: DU 6 Z: 6 s t 6 C up to 9 br DU 6 Z: 6 s t 8 C up to 9 br Operting temperture: 8 C For used t higher pressures or tempertures plese contct EndressHuser Electromgnetic comptibility (EMC): Interference emission to EN 5 8-, Interference immunity to EN 5 8- nd Industril Stndrd NAMUR, with V/m. Explosion Protection ATEX II G EEx i IIC T6...T5 (s. XA 9F-A) CSA Cl., Div., Gr. A-D Fitting for mounting brcket ø49 PG 6 (WADI) 7 ø58 DU 6 Z sensor dimensions in mm Fitting for mounting brcket ø49 PG 6 (WADI) 7 ø DU 6 Z sensor dimensions in mm

11 Process Connections Slip-On Flnge FAU 6 for DU 6 Z DN PN 6 (Code D) JIS K 6 (Code J) ANSI 4" 5 psi (Code A) Slip-On Flnge FAU 6 for DU 6 Z DN 5 PN 6 (Code D) JIS 5 K 6 (Code J) ANSI 6" 5 psi (Code A) D k ø5 A Mounting Brcket FAU A mounting brcket is vilble s n lterntive to the slip-on flnge. It llows the sensor to be suspended from the top of the tnk or silo. Order No.: Mx c b Slip-on flnge dimensions d A,5 A Key to slip-on flnge drwing for DU 6 Z Key to slip-on flnge drwing for DU 6 Z Mteril Stndrd Order No. A b C ø D ø d k No. d FAU 6 D P PP DN PN 6 FAU 6 D S St/pinted (DIN 57) FAU 6 D R.457 FAU 6 A P PP ANSI 4" 5 psi FAU 6 A S St/pinted (ANSI B 6.5) FAU 6 A R.457 FAU 6 J P PP JIS 6 K- FAU 6 J S St/pinted (JIS B ) FAU 6 J R.457 Mteril Stndrd Order No. A b C ø D ø d k No. d FAU 6 D P PP DN 5 PN 6 FAU 6 D S St/pinted (DIN 57) FAU 6 D R.457 FAU 6 A P PP ANSI 6" 5 psi FAU 6 A S St/pinted (ANSI B 6.5) FAU 6 A R.457 FAU 6 J P PP JIS 6 K-5 FAU 6 J S St/pinted (JIS B ) FAU 6 J R.457 Suggestion for sensor mounting: The DU 6 Z cnnot be used with DN 5 counterflnge since there is no corresponding seling surfce. Tighten the screws on opposite sides first; torque pprox. 5 7 Nm. Sensor DU Counterflnge or mounting pipe Slip-on flnge ø Mounting brcket dimensions in mm

12 Product Structure Sensor DU 6 Z Certificte U CSA Clss I, Div., Groups A-D S ATEX II G EEx i IIC T6...T5, s. XA 9F-A Mteril diphrgm PVDF DU 6 Z Product designtion Sensor DU 6 Z Certificte U CSA Clss I, Div., Groups A-D S ATEX II G EEx i IIC T6...T5, s. XA 9F-A Mteril diphrgm PVDF DU 6 Z Product designtion Slip-on Flnge FAU 6 for DU 6 Z nd DU 6 Z Process connection D DN PN 6 A ANSI 4" 5 psi J JIS 6 K- D DN 5 PN 6 A ANSI 6" 5 psi J JIS 6 K-5 Y9 others Mteril P Polypropylene (p e mx..5 br) S Steel/pinted R stinless steel.457 Y others FAU 6 Product designtion Supplementry Documenttion Ultrsonic mesurement Product Informtion PI 4F//en Nivosonic FMU 673 Z/678 Z Technicl Informtion TI 8F//en Nivosonic FMU 673 Z/678 Z Operting Instructions BA 7F//en Ultrsonic sensor DU 5 Z Technicl Informtion TI 78F//en EndressHuser GmbHCo. KG Instruments Interntionl P.O. Box D Weil m Rhein Germny Tel. ( 76 ) Fx ( 76 ) info@ii.endress.com Endress Huser The Power of Know How 5./PT TI 9F//en/7.3 CCS/CV8.