GR Variable area flowmeters - Marsh Inst

1 Variable area flowmeters KROHNE 08 area flowmetersVortex flowmetersFlow controllersElectromagnetic flowmetersUltrasonic flowmetersMass flowmetersLevel measuring instrumentsCommunications technologyEngineering systems & solutionsSwitches, counters, displays and recordersHeat meteringPressure and temperature2 Variable area flowmetersTechnical featuresFlowmeters operating on the float principle are suitable for both liquidsand gases. This method is inexpensive yet highly accurate and of Variable area flowmeters : Accurate measurement even at very low flow rates Standard rangeability of 10 : 1 (ratio of full-scale to lower limit value)

2 Suitable for low operating pressures Minimal pressure losses Local indication without the need for auxiliary power Can be used even with short or no straight inlet /outlet runs Essential components easily replaced Exact calculations to VDI s no alternative to reliabilityThat s why Variable area flowmeters fromKROHNE offer not only the maximum possible accuracy but also maximum wealth of experience and an intelligentquality assurance system enables usto place our VA meters in applicationsinaccessible to other manufacturers suchas nuclear power stations where safety is play it safe flowmeters from KROHNEThe KROHNE strategyKROHNE is at home in almost all plants andprocesses, as well as in all corners of theworld.

3 Being a global player, we are able toreact at any time to the widest variety ofrequests by our are in the most important committeesand industry groups, which enables us torecognize and often help set strategy aims at making it easy for thecustomer to do business with KROHNE byoffering the best products at the best overallconditions and coupled with the best consultation, service and support that theindustry has to - easy to work SelectorMetal measuring cones dk metal series for low to medium flow rates H series for medium to high flow rates suitable for high pressures and temperaturesGlass measuring cones The DK Glass series for low to medium flow rates VA, GA, series for medium to high flow ratesVA 40for universal applicationsVA 45for gas at lowoperating pressureGA 24with laminated glass paneDK 700for analytical processesDK 800, 46(I), 47(I), 48for low flow rates(batching operations)H 250 (stainless steel)

4 Standard flowmeteraccuracy class 250 / H 54 / M 10hazardous-dutydesign EEx dH 250 Ceramicwetted parts made ofaluminium oxide ceramicsH 54accuracy class 32, DK 34for low flow ratesaccuracy class 37 M8M / DK 37 M8 EMechanical orElectronic display,accuracy class 20low-costplastic versionChoosing the right flowmeterVariable-area flowmeters are fitted with measuring cones made of glassor metal . The glass measuring coneallows direct viewing of the process liquidand direct reading of the flow. The metal measuring coneis used for difficult operating conditions pressure temperature corrosion resistanceAs direct readings are not possible, these are equipped with amechanical, electromechanical or electronic re sure to find a measuring device in this product range to suit your specific devices are available for low operating pressures, high flowrates, for batching operations, for the food industry, and for principle4 Variable area flowmeters feature an upright tapered tube, wider end up,in which a specially shaped float moves freely up and fluid flows upwards through the tube.

5 Causing the float to lift acertain distance and form a gap between tube wall and float, so thatthe forces acting on the float are in forces act on the float: Constant force of gravity G Buoyancy A, which according to Archimedes principleis constant if fluid density is constant Force S, the upward force of the fluid flowing pastthe float, which depends on the flow rateFlowmeters which operate on the float principlehave an upright conical measuring tube of glass, metal or plastics in which a specially shaped floatis allowed to move freely up and down. With flowfrom bottom to top, the float adjusts so that buoy-ancy A and resistance Ware in equilibrium withmass M.

6 The flow values are read off from thescale at the level of the float reading measured value thus corresponds to a defin-ed annular gap, resulting from the conical form of the measuring tube and the specific position ofthe glass cones, the flow value can be readdirectly from a scale at the level of the float read-ing metal cones, the float position is transmittedto an indicator by magnetic Code 3513 describes the method usedto calculate scales for Variable area flowmeters toinclude all material and flow parameters, such asdensity, viscosity, pressure and method can also be used for scale conver-sions to accommodate changed operating software is available for this purpose:KROHNE Variable Area Calculation (KroVaCal)KROHNE Variable Area Selection (KroValSel)upward force on float S (W)buoyancy Amass M(gravity G)GASR eadling lines of various float shapes:ShapeA IIIA IIIB allguidedReading linefloatposition5 AccuracyAccuracy error%Measured Full-scale Measured Full-scale Measured Full-scale Measured Full-scale Measured Full-scaleFlow rate% conformity with VDI/VDE 3513, Sh.

7 2, accuracy for Variable area flowmeters is defined by various accuracy classes. The following totalerrors are permitted as a factor of the flow rate, measured as % ofmeasured value or % of full-scale accuracy classes 1 to 4, our instruments are calibrated with wateror air followed by conversion to customer-specified operating data andinstrument scaling. Accuracy class requires calibration at actual flowing from VDI/VDE Code 3513 Sheet 2 Each accuracy class is related to an error range which may not beexceeded at any point in the measuring permissible maximum error range is the sum of the following twopartial errors:1st partial error:3/4of the figure specified as the accuracy classequals the error as a percentage of the measuredvalue2nd partial error.

8 1/4of the figure specified as the accuracy classequals the error as a percentage of the full-scalerangeAuszug aus der VDI/VDE Richtlinie 3513 Blatt 2 For a specific measured value, the total error F in flow units can be calculated according to the following formula:M measured value in flow unitsE full-scale value in flow unitsK figure specified as the accuracy classF =3 M + 1 EK4 4 100()AccessoriesApart from the various instrument types andmaterials offered, additional options are alsoavailable to equip the instruments for available accessories, limit switches,remote data transmission system or panelmounting sets, are described in the individualflowmeter data ( US GPH)10 000 l/h(2642 US GPH) m3/h ( SCFM)310m3/h (192 SCFM)20 C (68 F) bar abs.

9 , 20 C ( psia, 68 F) bar (145 psig)100 C (212 F)glassPVDF/stainless steel, Hastelloy, PTFE, TFMBuna, Viton, EPDM threaded pipe connection G3 G 2tube nozzle 15 .. 52 mm ( .. 2 )Flanges DN 15 .. 50 (1/2 .. 2 )Pipe connections in the food industryType V screw connection 375 mm ( )Type S tube nozzle DN 15: 400 mm ( )tube nozz DN 25: 450 mm ( )Type F flange connection 425 mm ( )Type A aseptic DN 15: 375 mm ( )DN 40, DN 50: 400 mm (11/2 , 2 : )max. 2 Product Overview6GA 24 Heavy-duty (rotating connections)ALTOSONICM easurable conditionsWaterAirAccuracy classOperating dataMax. pressureMax. temperatureMaterialsMetering coneOther wetted partsGasketsConnectionConnection dimensionLimit ( US GPH)10 000 l/h(2642 US GPH) m3/h ( SCFM)310m3/h (192 SCFM)20 C (68 F) bar abs.

10 , 20 C ( psia, 68 F) (Option )10 bar (145 psig)120 C (248 F)glassgrey cast iron/stainless steel/PTFEN eoprene/PTFEF langesDN 15 .. 50 ANSI 1/2 .. 2 500 mm ( )max. 2VA 40 Various connections for universal applicationsGlass cone flowmeters7 Product OverviewALTOSONICM easurable conditionsWaterAirAccuracy classOperating dataMax. pressureMax. temperatureMaterialsMetering coneOther wetted partsGasketsConnectionConnection dimensionLimit switchesGlass cone flowmetersK 20 Economy version for machine monitoring5l/h ( US GPH)24 000 l/h (6340 US GPH) m3/h ( SCFH)300m3/h (186 SCFH)20 C (68 F) bar abs., 20 C ( psia, 68 F) bar (87 psig) 10.