Operating Instructions METTLER TOLEDO DL36 KF Coulometer
Contents Contents Page 1. Introduction .................................................................................................. 3 2. Safety measures ........................................................................................... 4 3. Measurement principle ................................................................................ 5 4. Putting into operation .................................................................................. 6 4.1 4.2 4.
Contents Page 10. 10.1 10.2 Error messages and malfunctions ............................................................. 26 Error messages of the DL36 .......................................................................... 26 Other malfunctions ......................................................................................... 26 11. 11.1 11.2 11.3 11.4 11.5 11.6 11.7 11.8 11.9 Maintenance and servicing .........................................................................
Introduction 1. Introduction Moisture in sugar or salt influences its pouring properties. Traces of moisture in brake fluid have an adverse effect on the functioning of vehicle brakes. Impurity water in the hydraulic oil of aircraft leads to a dangerous lowering in the performance of the hydraulic system. As the quality of products frequently depends on their moisture content, it is essential that this be known as accurately as possible.
Safety measures 2. Safety measures The DL36 has been tested for the Operating Instructions. However, performing your own tests of the methods and purposes you intend safety measures. experiments and intended purposes documented in the this does not absolve you from the responsibility of product supplied by us regarding its suitability for the to use it for.
Measurement principle 3. Measurement principle In the Karl Fischer method for determination of the moisture content, water (H2O) reacts with iodine (I2) and sulfur dioxide (SO2) in the presence of methanol (CH3OH) and a base (RN). H2O + I2 + SO2 + CH3OH + 3RN → [RNH] SO4CH3 + 2[RNH]I (1) In the volumetric titration, iodine is added as the titrant. In the coulometric titration, iodine is generated electrolytically by an iodide-containing anolyte.
Putting into operation 4. Putting into operation 4.1 Preparing the titration cell WARNING Never inhale the vapors of Karl Fischer reagents and avoid skin contact! The reagents could hazard your health. – Remove the Teflon stopper of the titration cell and carefully slip the magnetic stirrer into the cell; replace the stopper. – Place the titration cell in the holder.
Putting into operation 4.2 Attaching peripheral devices You can attach, e.g. the GA42 Printer and an analytical balance from METTLER TOLEDO and a computer (see Section 8.5: Selecting peripheral devices and Section 12: Standard and optional equipment). Input for detection electrode Printer interface Input for inner burette Balance interface Voltage selector and fuse holder Computer interface Connector for power cable Instrument on/off switch 4.
Keypad and display 5. Keypad and display 5.1 The keypad Enter calculation and report parameters Titration 7 8 9 Esc Result 4 5 6 CE Setup 1 2 Stirrer 0 .
Keypad and display Pot. 5.2 201.5 mV Example with stable drift, this also means that the electrode potential must lie in the vicinity of this value at the end point of a titration. The display The display has space for 16 characters.
The first titration 6. The first titration To determine the moisture content of a sample accurately, parameters are stored in the DL36 which you can change to match your sample. On delivery, the instrument has default parameters stored which you can use to determine the moisture content in µg of many organic substances, e.g. 99% ethanol. The DL36 is switched on, the display shows . – Press the Run key: 112 ✽ Pre-Titr 5 Ready 2 Stable ID ? ETHANOL 2 Start Samp.In.
The method 7. The method A method with default parameters is stored in the DL36. These comprise two groups, the measurement and result parameters, which you call up with the Titration and Result keys and can adapt to meet the requirements of the individual determinations. You can call up the parameters which support the method using the Setup key (see Section 8). Notes 1. During the titration, the Titration, Result and Setup keys are locked! 2.
The method 7.2 Printing out a method You can always print out the parameters of a group: • When you have selected Titration and press the Print key, the corresponding parameters are printed out. • When you have selected Result and press the Print key, the calculation and report parameters are printed out. These parameters are printed out separately when you press the Print key while a parameter of the corresponding menu is displayed. 7.
The method Notes 1. Stirring and titration time Run Run Sample injection Stirring time t(stir) t(wait): no abort of the titration No iodine generation t(max) or the time until defined drift stop is reached Iodine generation Automatic drift compensation by internal calculation Titration time for which you can select the type of drift compensation (see page 14) The titration time is printed out (Titr. time) if you select "GLP" for the report (see Section 7.3.2). 2.
The method 7.3.2 Result parameters This parameter group comprises three parts: 1. the calculation parameters (Calculation) 2. the selection of the report (Report) 3. the parameters for the recalculation (Recalculation). The tables shown follow this subdivision. 1.
The method Calculation formulae Formula No. Result in Formula 1 µg or mg factor ⋅ (Tvalue – drift ⋅ t – blank) 2 ppm or % (entry of the sample weight) factor ⋅ Tvalue: Result of the titration in µg drift: Drift value in µg/min (Tvalue – drift ⋅ t – blank) weight t: Titration time in min (see page 13) blank: Blank value in µg weight: Sample weight in g 2. Report parameters You can choose between two report formats: short-form and GLP format (GLP: Good Laboratory Practice).
The method 3. Parameters for recalculation If, e.g. you have made a mistake when entering the weight or have selected a different result unit, you can perform recalculations after every sample determination. Key selection Result Calculation ↑ Select Report ↑ Select Recalculation ↑ Description Enter Weight? 0.1243.......0.1234 Change the weight if need be. Enter Drift? 1.62 Change the drift value if need be. Enter Blank? 0 Enter a blank value if need be.
Setup 8. Setup Under this key you call up menus and functions which support the method and allow selection of the peripheral devices. When you press the key, the following appears Setup[1-8]? When you enter one of the numbers and confirm with Enter, you can define or select the following parameters: 1: Reagent capacity 2: Date & time 3: User identification (User ID) 4: Instrument identification (Instr ID) 5: Peripheral devices (Option) 6: Weight entry (Wt.
Setup Display/Entry (example) Description Setup [1-8]? 1 "Reagent capacity" flashes on the display. Enter A.Capa. [mg]? 61 Display of the summed electrolytic current for the anolyte – converted to mg H20. When you change the anolyte, enter 0. Enter C.Capa. [mg]? 61 Enter Alarm set: off ↑ You are not informed when the defined capacity limits are exceeded (see below). Alarm set: on ↑ You are informed when the defined capacity limits are exceeded (see below).
Setup 8.3 Entering the user identification In this menu you can enter your name; it appears on every GLP report. You can enter the user and the instrument identification alphanumerically using the "minus", "period" and numeric keys. When you press this key for the first time, the letter A is displayed, for the second time B → C → ... Z → . (period) → – (minus) → "space" → A →... When you press this key for the first time, a "space" is displayed, for the second time a – (minus) → . (period) → Z → Y → ...
Setup 8.5 Selecting peripheral devices In this menu you select the printer and the balance you have attached to the DL36. For a computer you need to define the corresponding configuration data. The pin assignment of the RS232C interfaces is described in Section 13.2. 1. Printer You can attach a METTLER TOLEDO GA42 or another commercially available printer. In the latter case, you need to define the configuration data.
Setup Notes 1. For all balances you must select the default setting with unidirectional transmission mode "Send Cont.". 2. If you attach a balance using the LC-RS9 cable, you must set positions 7, 3 and 4 (switches left, middle and right). 3. Computer If you attach a computer, you must select the configuration of the RS232C interface. Key selection Display/Entry Setup [1-8]? Setup Description 5 "Option" flashes on the display.
Setup 8.7 Selecting entry of the sample identification You can choose whether you enter the sample identification before or after the titration or not at all. Key selection Description Display/Entry Setup [1-8]? Setup 7 Enter ID entry:before ↑ Enter Setup [1-8]? 8.8 "ID entry" flashes on the display. Select between before, after and off. off: no inquiry of the sample identification during the titration, but the identification last entered will be automatically recorded.
Sample determinations 9. Sample determinations 9.1 Weight transfer from a balance You have selected a variable weight as a calculation parameter (see Section 7.3.2) and "before the titration" as the entry for the weight and sample identification (see Sections 8.6 and 8.7). Notice: The mass unit of the balance must be set to g! The anolyte solution is anhydrous, its drift stable (see Section 6). – Siphon off your sample with a syringe, place the syringe on the balance and tare to 0.
Sample determinations 9.2 Tips for sample addition The titration cell of the DL36 is set up for the injection of samples. 1. During sample preparation and sample addition, work as quickly as possible to keep the effect of atmospheric moisture to a minimum. As most samples are stored and transported under standard conditions of temperature and pressure, you should also weigh in and inject under these conditions.
Sample determinations 9.3 Tips for accurate determinations 1. We advise always using the DL36 in the operating mode "Pretitration" (standby titration). 2. Always wait for a stable drift before you inject the sample. This allows determination of an exact value for the drift change per minute, which is incorporated in the calculation of the result. 3. Titrate the cell overnight when you determine samples whose absolute moisture content is less than 50 µg (standby titration). 4.
Error messages and malfunctions 10. Error messages and malfunctions 10.1 Error messages of the DL36 Error message Cause Measures A.Capacity Over! The summed electrolytic current (converted to mg H2O) of the anolyte is greater than its capacity • Change anolyte • Set capacity of the anolyte to 0 (see Section 8.1) C.
Error messages and malfunctions Fault Possible causes Measures Drift too high Leaks in the system Change septum and drying agent, (apply very thin coating of grease to glass joints) Capacity limits of the anolyte/catholyte reached or "wrong" reagent used Change reagents Membrane wetted with moisture or cracked Clean inner burette or replace Anode touching the membrane Insert anode adjustment element between membrane and anode and set a distance between 1.
Maintenance and servicing 11. Maintenance and servicing 11.1 Charging internal battery A battery is responsible for the internal clock. Contact the METTLER TOLEDO Service when it is discharged, i.e. when the date and time are no longer correctly displayed. 11.2 Line voltage, line fuses The DL36 can operate in different voltage ranges. The voltage selector is used to select the range.
Maintenance and servicing 11.3 Greasing the glass joints – Turn the stopper/electrode/drying tube of the titration cell about once a week to check their contact and to prevent them from sticking. – Apply a very thin coating of grease if the contact (tightness) is no longer assured. Notice: If an execessive amount of grease is applied, it could enter the titration cell and increase the drift owing to the moisture it contains! 11.
Maintenance and servicing 2. Anolyte You should change the anolyte when • the capacity limit is reached (see Section 8.1), • the drift is too high (>10 µg/min) or the status "Stable" is no longer reached, • its volume in the titration cell has reached 150 mL (upper marking on the titration cell); if the anolyte is diluted too highly, the sensitivity is lowered and the titrations take longer. – Siphon off the anolyte using the polyethylene bottle.
Maintanance and servicing 2. Cleaning with chromic acid (if foreign matter has collected on the membrane or the platinum surface). – – – – – Perform the first 3 steps as described under point 1. Add approx. 10 mL chromic acid and place in a beaker. Fill the beaker with chromic acid until the level in the cathode is reached. Allow to stand overnight. Empty the inner burette and wash the cathode five or six times with pure water until the yellow color disappears (rinse chromic acid from the membrane).
Standard and optional equipment 12. Standard and optional equipment You can reorder every part with an order number; the numbers in brackets refer to the quantity supplied with the DL36. 12.1 Standard equipment Order No.
Standard and optional equipment Order No. Drying tube (1) 105016 • filled with silica gel Suction bottle made of polyethylene (1) 105123 Plastic funnel (1) 105124 Septum (10), Ø: 12/2 mm set of 10 Anode adjustment element (1) 12.
Standard and optional equipment Order No. Syringe 1 mL Syringe 10 mL set of 100 set of 100 71492 71482 Injection needle set of 12 71483 80 mm x 1.2 mm METTLER TOLEDO printer 17.3 19.3 75 g 8.00 19 g 7.77 3 g 6.55 3 10.5 4 g g 8.09 06 g 5.87 7 g 3.20 6 g 1.09 5 g 8g GA4 2 Prin GA42 METTLER TOLEDO ter Cable for GA42 Printer 51190362 Cable for DPU-201GS printer from Seiko Instruments 51106171 Cable for InkJet printers from 51190363 Canon, HP and EPSON (D-submin. 9-pin, female, D-submin.
Standard and optional equipment Order No.
Technical data 13. Technical data 13.
Technical data Housing Polyester Titration cell Pyrex® Display LCD, 16 characters Dimensions width: 260 mm, depth: 395 mm, height: 270 cm Weight approx. 6.4 kg Power supply 100/120/220/230/240 VAC ±10% 50/60 Hz 50 VA Fuses T1,6L250V; T3,15L250V Ambient conditions • • • • 13.
Technical data 2. Balance interface RS232C interface for the attachment of a balance with unidirectional transmission mode "Send Cont." Pin assignment 1 3 2 6 4 8 7 5 9 GND DTR TXD RXD Preset configuration on attachment of one of the possible balances from: Selection Mettler Shimadzu A&D Sartorius Baud rate 2400 1200 2400 1200 Parity even none even none Data bits 7 8 7 8 Stop bits 1 1 1 1 Default 3.
Index 14.
Index Select key 8 Septum 29 Servicing 28 Setup 17 Setup key 11 Short-form report 15 Silica gel 29 Stable 10 Standard equipment 32 Standard method 11 Stirrer key 8, 11 Stirring speed 11 Stirring time t(stir) 12, 13 Stop key 8 t(max) 12, 13 t(stir) 12, 13 t(wait) 12, 13 Technical data 36 Time 18 Titration cell 5 Titration key 11, 12 Titration parameters 12 Titration sequence 10 Titrationszeit 13 Units 14 User identification 19 Voltage 28 Voltage selector 28 Weight entry 21 Weight transfer 23 40 METTLER TO
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