CellOx 325 - Global Water Instrumentation, Inc.

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CellOx 325 - Global Water Instrumentation, Inc.

Operating manualCellOx 325Dissolved oxygen sensor17


CellOx 325Copyright© Weilheim 2002, WTW GmbH & Co. KGReprinting - even as excerpts - is only allowed with the explicit written authorizationof WTW GmbH & Co. KG, Weilheim.Printed in Germany.18


CellOx 325ContentsCellOx 325 - Contents1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202 Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213 Commissioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214 Measuring / Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . 224.1 Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224.2 Measuring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224.3 Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225 Maintenance, cleaning, replacement . . . . . . . . . . . . . . . . 235.1 General maintenance instructions . . . . . . . . . . . . . . . . . . 235.2 Exterior cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235.3 Changing the electrolyte and membrane head . . . . . . . . 245.4 Cleaning the electrodes . . . . . . . . . . . . . . . . . . . . . . . . . 265.5 Checking the sensor for freedom from zero-current . . . . 285.6 Disposal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 296 What to do if... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 297 Technical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 308 Wear parts and accessories . . . . . . . . . . . . . . . . . . . . . . . 3219


Overview CellOx 3251 OverviewConstruction1 234 5 6 7 81 WP 90 membrane cap (filled with electrolyte solution)2 Shaft3 Connection head4 Gold working electrode (cathode)5 Insulator6 Lead counter electrode (anode)7 Ventilation area8 Temperature sensor and auxiliary electrodeRecommendedfields ofapplication On site measurements in rivers, lakes and wastewater Applications in water laboratories BOD measurements20


CellOx 325Safety2 SafetyThis operating manual contains special instructions that must be followedduring the operation of the Dissolved Oxygen (D.O.) sensor.Always keep this operating manual in the vicinity of the sensor.Special userqualificationsGeneral safetyinstructionsThe membrane cap of the D. O. sensor is filled with a small amount of analkaline electrolyte solution. All maintenance work that requires dealing withthe electrolyte solution must only be carried out by persons who are familiarwith the safe handling of chemicals.The individual chapters of this operating manual use safety labels like the onebelow to indicate danger:Cautionindicates instructions that must be followed precisely in order to avoidslight injuries or damage to the instrument or the environment.3 CommissioningScope of delivery D. O. sensor CellOx 325, filled with electrolyte solution and operable 3 exchange membrane caps WP 90 Calibration and storage vessel, OxiCal ® -SL Operating manualNoteThe membrane cap that is mounted on the sensor for delivery serves mainlyas a transport protection. Depending on the duration of the transport and storageperiod, it may have a shortened operational lifetime. If the measuringsystem cannot be calibrated (error message on the instrument), please proceedaccording to section REPLACING THE ELECTROLYTE SOLUTION AND MEM-BRANE CAP.Getting the sensorready formeasuringConnect the sensor to the measuring instrument. The sensor is immediatelyready to measure. It is not necessary to polarize the sensor.21


Measuring / Operation CellOx 3254 Measuring / Operation4.1 CalibrationNoteFor calibration, please refer to the operating manual of the measuring instrument.4.2 MeasuringPlease note the required minimum immersion depth and minimum flow (seechapter 7 TECHNICAL DATA).The minimum flow can be provided in different ways, e. g.: The flow velocity of the water to be measured is sufficient (aeration tank,water pipe, stream) Slowly pull the sensor through the water by hand (lake, container), or Use a flow aid, e. g. a magnetic stirrer with stirring device (see chapter 8WEAR PARTS AND ACCESSORIES)4.3 StorageAlways store the sensor in the calibration vessel at a temperature of 0 to+50 °C. Make sure that the sponge in the calibration vessel is always moist.Calibration vessel,OxiCal ® -SL1 2Moisten the sponge: Remove the cap (1). Take out the sponge (2), wet it, then slightly squeeze it out. Reinsert the sponge and close the calibration vessel with the cap.22


CellOx 325Maintenance, cleaning, replacement5 Maintenance, cleaning, replacement5.1 General maintenance instructionsFor your safetyWhen dealing with the ELY/G electrolyte solution, observe the followingsafety instructions:CautionThe ELY/G electrolyte solution irritates eyes and skin. When dealingwith the ELY/G electrolyte solution, observe the following points: During working activities, always wear suitable protective glovesand protective goggles/face shield. If it comes into contact with the skin, rinse thoroughly with water andimmediately change contaminated clothing. If it comes into contact with the eyes, rinse thoroughly with waterand consult a doctor. Follow the safety datasheet.CautionBefore all maintenance activities, disconnect the sensor from theinstrument.NoteInformation on how to order wear parts and maintenance accessories can befound in chapter 8 WEAR PARTS AND ACCESSORIES.5.2 Exterior cleaningCleaning agentsContaminationLime sedimentsFat/oilCleaning proceduresImmerse in acetic acid for 1 minute (volumeshare = 20 %)Clean with warm water that contains washing-upliquidAfter cleaning, thoroughly rinse with deionized water and recalibrate ifnecessary.23


Maintenance, cleaning, replacement CellOx 3255.3 Changing the electrolyte and membrane headCautionBefore starting to work with the sensor, please note the GENERALMAINTENANCE INSTRUCTIONS on page 23.GeneralinformationWTW delivers the sensor ready to operate (see section 3). The electrolytesolution and the membrane head must only be replaced if: a calibration error occurs and the membrane is heavily contaminated the membrane is damaged the electrolyte solution is exhausted in case of a leak message by the measuring instrument.Changing the electrolyte solution and the membrane headUnscrew the membranehead.Caution: Electrolyte solution!For disposal of the membranehead and electrolyte solution,see section 5.6.Rinse the sensor head withdeionized water.Carefully rub and dry thecounter electrode with a lintfreepaper towel.RL/GImmerse the sensor head includingthe counter electrodein RL/G cleaning solution.Allow to react for 1 to 3 minutes.Thoroughly rinse the sensorhead with deionized water.H O 2Water the counter electrode indeionized water for at least10 minutes.24


CellOx 325Maintenance, cleaning, replacementELY/GCarefully shake off the dropsof water.Fill a new membrane cap withELY/G electrolyte solution.Remove any air bubbles bycarefully tapping the membranehead. Additionally, youcan prevent air bubbles bythrowing the first fill away andrefilling the membrane head.ELY/G4mmThoroughly rinse the sensorhead with electrolyte solution.Hold the sensor inclined andscrew on the membrane headfingertight using a paper towel.Excess electrolyte solutionis forced out of the ventilationarea.Check the filling:Inspect the face surface. Noair bubbles may be presentwithin the dashed circle(approx. the black area). Airbubbles outside this area donot interfere.NoteFor measurements under high pressure the filling must be completelyfree of air bubbles.Readiness to measureAfter approx. 30 to 50 minutes, the sensor is ready for operation.Subsequently calibrate the sensor.NoteIf you want to measure very low oxygen concentrations (< 0.5 %saturation), we recommend to let the sensor rest overnight andthen calibrate it.25


Maintenance, cleaning, replacement CellOx 3255.4 Cleaning the electrodesCautionBefore starting to work with the sensor, please note the GENERALMAINTENANCE INSTRUCTIONS on page 23.GeneralinformationCleaning is only required in cases of slopes that are too small or too large(sensor cannot be calibrated) that cannot be resolved by changing the membranehead and electrolyte solution.Cleaning the electrodesSF 300Unscrew the membranehead.Caution: Electrolyte solution!For disposal of the membranehead and electrolyte solution,see section 5.6.Rinse the sensor head withdeionized water.Using the rough side of thewet SF 300 polishing strip,polish off any contaminationfrom the gold working electrodeusing light pressure.Caution: Do not use any conventionalsandpaper or glassfiberbrushes.Rinse the sensor head withdeionized water.Wipe the counter electrodewith a lint-free paper toweland carefully remove anyloose white deposits.RL/GImmerse the sensor head includingthe counter electrodein RL/G cleaning solution.Allow to react for 1 to 3 minutes.26


CellOx 325Maintenance, cleaning, replacementThoroughly rinse the sensorhead with deionized water.H O 2Water the counter electrode indeionized water for at least10 minutes.Carefully shake off the dropsof water.ELY/GELY/GFill a new membrane cap withELY/G electrolyte solution.Remove any air bubbles bycarefully tapping the membranehead. Additionally, youcan prevent air bubbles bythrowing the first fill away andrefilling the membrane head.Rinse the sensor head withelectrolyte solution.4mmHold the sensor inclined andscrew on the membrane headfingertight using a paper towel.Excess electrolyte solutionis forced out of the ventilationarea.Check the filling:Inspect the face surface. Noair bubbles may be presentwithin the dashed circle(approx. the black area). Airbubbles outside this area donot interfere.27


Maintenance, cleaning, replacement CellOx 325NoteFor measurements under high pressure the fill must be completely free of airbubbles.Readiness tomeasureAfter approx. 30 to 50 minutes, the sensor is ready for operation. Subsequentlycalibrate the sensor.NoteIf you want to measure very low oxygen concentrations (< 0.5 % saturation),we recommend to let the sensor rest overnight and then calibrate it.5.5 Checking the sensor for freedom from zero-currentThe sensor is zero-current free. Checking the sensor for freedom from zerocurrentis only necessary in the case of malfunctions that cannot be remediedby exchanging the electrolyte solution and membrane head or by cleaningthe electrodes.There are two possibilities to check the sensor for freedom from zero-current: Measurement in a nitrogen atmosphere (recommended method) Measurement in a sodium sulfite solution according to DIN EN 25814/ISO 5814.CautionIf you check the sensor according to DIN EN 25814/ISO 5814, do notleave the sensor in the sodium sulfite solution for more than 2 minutes.Danger of sensor poisoning!Test criterionThe sensor is OK if the measuring instrument displays < 1 % DO saturationafter 2 minutes.28


CellOx 325What to do if...5.6 DisposalCautionThe ELY/G electrolyte solution irritates eyes and skin. When dealingwith the ELY/G electrolyte solution, observe the following points: During working activities, always wear suitable protective glovesand protective goggles/face shield. If it comes into contact with the skin, rinse thoroughly with water andimmediately change contaminated clothing. If it comes into contact with the eyes, rinse thoroughly with waterand consult a doctor. Follow the safety datasheet.Sensor andmembrane headElectrolytesolutionFor disposal, unscrew the membrane head and rinse the sensor andmembrane head with water. We recommend disposing of the sensor withoutthe membrane head as electronic refuse. The membrane head may bedisposed of with the household refuse.Disposal according to the safety data sheet.6 What to do if...Error symptom Cause RemedyThe sensor is in the airand the display shows0.0 mg/l or 0 % O 2– No connection betweenmeasuring instrument and sensor– Cable defective– No electrolyte in the membraneheadThe sensor cannot becalibratedThe sensor still cannotbe calibrated afterchanging the electrolyteand membrane headLeak display appearsIncorrect temperaturedisplayMechanical damage tothe sensor– Contaminated membrane head– Electrolyte depleted– Contaminated electrodes orsensor toxification– Membrane head not screwed ontight enough– Hole in the membrane– Check connection betweenmeasuring instrument and sensor– Replace and refill the membranehead (see section 5.3)– Replace and refill the membranehead (see section 5.3).Subsequently, wait for 30 to50 min and recalibrate.– Clean the electrodes (seesection 5.4)– Screw membrane head tighter– Replace and refill the membranehead (see section 5.3)– Temperature sensor defective – Return the sensor– Return the sensor29


Technical data CellOx 3257 Technical dataGeneral features Measuring principle Membrane covered galvanic sensorTemperature compensation IMT compensation(calculated by the measuring instrument)Dimensions(in mm)Weight170 g (with 1.5 m cable)Materials Working electrode GoldCounter electrodeLead– Shaft– Connection head– Screwed cable gland– Membrane headPOMMembrane FEP, 13 µmSensor headEpoxy, PEEKThermistor housing VA steel 1.4571SealsFPM (Viton)Connection cable Lengths 1.5 ... 20 mDiameter6 mmSmallest allowedPermanent bend: 80 mmbend radiusSingle time or short time bend: 50 mmPlug typeSocket, 8 pinsPressureresistanceSensorSensor cablePlugIP 68 (6 bar)IP 68 (2 bar)IP 67 (when plugged in)The CellOx 325 meets the requirements according to article 3(3) of the97/23/EC directive ("Pressure equipment directive").30


CellOx 325Technical dataMeasurementconditionsMeasuring ranges at 20 °C 0 ... 50 mg/l O 20 ... 600 % O 2 saturation0 ... 1250 mbar O 2 partial pressureTemperature range 0 ... 50 °CMax. allowed overpressure 6·10 5 Pa (6 bar)Depth of immersion min. 6 cmmax. 20 m (depending on the cable length)Operating positionanyApproach flow> 3 cm/s at 10 % measurement accuracy10 cm/s at 5 % measurement accuracy18 cm/s at 1 % measurement accuracyCharacteristic dataon deliveryZero signalResponse time at 20 °COxygen own consumptionat 20 °CDriftWorking life< 0.1 % of the saturation valuet 90 (90 % of the final value display) < 10 st 95 (95 % of the final value display) < 16 st 99 (99 % of the final value display) < 60 s0.008 µg·h -1 (mg/l) -1approx. 3 % per month in the operating conditionmin. 6 months with one electrolyte fillPin assignment31


Wear parts and accessories CellOx 3258 Wear parts and accessoriesWear parts andmaintenanceaccessoriesDescription Model Order no.Set of exchange membrane caps (3 pieces) WP 90/3 202 725Electrolyte solution ELY/G 205 217Cleaning solution for lead counter electrode RL/G 205 204Polishing film SF 300 203 680Accessory kit, comprising:– 3 exchange membrane caps WP 90– Polishing film SF 300– Electrolyte solution ELY/G– Cleaning solution RL/GZBK 325 202 706Accessories Description Model Order no.Calibration and storage vessel OxiCal ® -SL 205 362Magnetic stirrer Oxi-Stirrer 300 203 810Stirring accessory - provides a constant, RZ 300 203 824defined flow of the sensor, in conjunctionwith the Oxi-Stirrer 300Funnel set - for BOD measurements in TS 19 205 710Winkler bottlesKarlsruhe bottle - suitable for BODKF 12 205 700measurementsFixing ring, recommended for measurementsFR 19 205 712in Karlsruhe bottlesFlow-through accessory - for pressure-free D 201 203 730oxygen measurement with flow-throughquantities from 25 to 65 ml/min.Shaft extension SVL 325 903 832Plastic armoring A 325/K 903 830Battery stirrer for depth measurements - onlyin conjunction with the A 325/K plasticarmoringBR 325 203 826NoteFor further accessories, refer to the WTW catalog or the Internet.32

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