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wtw inoLab pH 720 Operating Manual

Laboratory ph meter
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  • Page 2 Copyright Weilheim 2004, WTW GmbH © Reprinting - even as excerpts - is only allowed with the ex- plicit written authorization of WTW GmbH, Weilheim. Printed in Germany.

  • Page 3: Table Of Contents

    pH 720 Contents Overview ....... 5 1.1 Keyboard ......6 1.2 Display .
  • Page 4 Contents pH 720...

  • Page 5: Overview

    720 Overview Overview The compact inoLab pH 720 precision pH meter lets you perform pH measurements rapidly and reliably. The inoLab pH 720 provides the highest degree of operating comfort, reliability and measuring safety for all applications. ® The proven MultiCal calibration procedures and special AutoRead function support your work with the pH meter.

  • Page 6: Keyboard

    Overview pH 720 Keyboard 1 Activate/deactivate AutoRead function 2 Call up calibration procedure 3 Select measuring mode 4 Measuring instrument ON/OFF 5 Reduce values, scroll 6 Increase values, scroll 7 Confirm inputs, start AutoRead...

  • Page 7: Display

    Plug-in power supply (option) Caution Only connect probes to the instrument that cannot feed ex- cessive voltages or currents (> SELV and > circuit with cur- rent limiter). Almost all commercial electrodes - especially WTW elec- trodes - meet these requirements.
  • Page 8 Overview pH 720...

  • Page 9: Safety

    pH 720 Safety Safety This operating manual contains basic instructions that you must follow during the commissioning, operation and main- tenance of the pH meter. Consequently, all responsible per- sonnel must read this operating manual before working with the instrument. The operating manual must always be available within the vicinity of the instrument.

  • Page 10: Authorized Use

    In this event, wait until the temperature of the instrument reaches room tem- perature before putting the instrument back into operation. Caution The instrument is only allowed to be opened by personnel authorized by WTW.
  • Page 11 pH 720 Safety Safe operation If safe operation is no longer possible, the instrument must be taken out of service and secured against inadvertent op- eration. Safe operation is no longer possible if: the instrument has been damaged in transport the instrument has been stored under adverse conditions for a lengthy period of time the instrument is visibly damaged...
  • Page 12 Safety pH 720...

  • Page 13: Commissioning

    720 Commissioning Commissioning Scope of delivery Laboratory measuring instrument, inoLab pH 720 Operating manual and short manual 4 x type AA Mignon 1.5 V batteries Initial commissioning Perform the following activities: Set the °C or °F Set the resolution Connect the plug-in power supply (optional).
  • Page 14 Caution Use original plug-in power supplies only (see chapter 7 T ECHNICAL 1 Insert the plug (1) into the socket (2) of the pH meter. 2 Connect the original WTW plug-in power supply (3) to an easily accessible mains socket.

  • Page 15: Operation

    pH 720 Operation Operation Switch on the instrument 1 Place the instrument on a flat surface and protect it against intense light and heat. 2 Press the key. The Display test appears briefly on the display. The instrument then switches automatically to the previously selected measuring mode.

  • Page 16: Measuring

    Operation pH 720 Measuring Preparatory Perform the following activities when you want to measure: activities 1 Connect the pH electrode to the instrument. 2 Adjust the temperature of the buffer or test solutions or measure the current temperature if the measure- ment is made without a temperature probe.

  • Page 17: Measuring The Ph Value

    pH 720 Operation 4.2.1 Measuring the pH value 1 Perform the preparatory activities according to sec- tion 4.2. 2 Immerse the pH electrode into the test sample. 3 Press the key until pH appears in the status dis- play. The pH value appears on the display. AutoRead AR The AutoRead function (drift control) checks the stability of (Drift control)

  • Page 18: Measuring The Redox Voltage

    Operation pH 720 Note The current AutoRead measurement (with acceptance of the current value) can be terminated at any time by pressing 4.2.2 Measuring the Redox voltage The instrument can measure the Redox voltage (mV) of a solution when connected with a Redox electrode, e.g. SenTix ORP.

  • Page 19: Calibrating

    You can choose between 3 calibration procedures: AutoCal TEC is specially adapted to the WTW technical buffer solutions as a fully automatic two or three-point calibration. The buffer solutions are automatically recognized by the instrument. AutoCal DIN...
  • Page 20 Operation pH 720 Calibration After the calibration, the instrument automatically evaluates evaluation the current status. The asymmetry and slope are separately evaluated. The worst evaluation appears on the display. Display Asymmetry Slope [mV] [mV/pH] -15 ... +15 -60.5 ... -58 -20 ...

  • Page 21: Autocal Tec

    720 Operation 4.3.1 AutoCal TEC Use any two or three of the WTW technical buffer solutions for this procedure in increasing or decreasing order (pH 2.00, 4.01, 7.00, or 10.01). Note The calibration for pH 10.01 is optimized for the WTW tech- nical buffer solution TEP 10 Trace or TPL 10 Trace.
  • Page 22 Operation pH 720 5 Thoroughly rinse the electrode with distilled water. 6 If necessary, set the temperature of the second buffer solution by pressing 7 Submerse the electrode in the second buffer solution. 8 Press the key. AR flashes on the display. The electrode voltage (mV) appears on the display.
  • Page 23 pH 720 Operation 11 Press the key. Three-point Ct3 appears on the display. calibration 12 Thoroughly rinse the electrode with distilled water. 13 If necessary, set the temperature of the third buffer solution by pressing 14 Submerse the electrode in the third buffer solution. 15 Press the key.

  • Page 24: Autocal Din

    Operation pH 720 4.3.2 AutoCal DIN Use two or three different DIN buffer solutions (type A, C, D or F with the pH values 1.679, 4.006, 6.865, 9.180) for this procedure in increasing or decreasing order. Note Steps 2, 6 and 13 are not required if you use a temperature probe.
  • Page 25 pH 720 Operation 5 Thoroughly rinse the electrode with distilled water. 6 If necessary, set the temperature of the second buffer solution by pressing 7 Submerse the electrode in the second buffer solution. 8 Press the key. AR flashes on the display. The electrode voltage (mV) appears on the display.
  • Page 26 Operation pH 720 11 Press the key. Three-point Cd3 appears on the display. calibration 12 Thoroughly rinse the electrode with distilled water. 13 If necessary, set the temperature of the third buffer solution by pressing 14 Submerse the electrode in the third buffer solution. 15 Press the key.

  • Page 27: Concal

    pH 720 Operation 4.3.3 ConCal Two-point Use two buffer solutions for this procedure: calibration pH 7.0 ± 0.5 any other buffer solution Note Steps 2 and 9 are not required if you use a temperature probe. 1 Press the key repeatedly until the ConCal func- tion display appears.
  • Page 28 Operation pH 720 8 Thoroughly rinse the electrode with distilled water. 9 If necessary, set the temperature of the second buffer solution by pressing 10 Submerse the electrode in the second buffer solution. 11 Press the key. The second measured pH value appears on the dis- play.
  • Page 29 pH 720 Operation Single-point Use any buffer solution for this rapid method. The calibration calibration will be the more exact the nearer the pH value of the buffer solution is to that of the test sample. Note Only the electrode asymmetry is determined in single-point calibration.

  • Page 30: Reset

    Operation pH 720 Reset Basic settings The following functions are reset (initialized) to the values they had on delivery: Measuring mode Asymmetry 0 mV Slope -59.16 mV/pH Calibration procedure AutoCal TEC Temperature, manual 25°C Resolution of pH display 0.01 Proceed as follows: 1 Press and hold down the key.

  • Page 31: Maintenance, Cleaning, Disposal

    pH 720 Maintenance, cleaning, disposal Maintenance, cleaning, disposal Maintenance The measuring instrument is almost maintenance-free. The only maintenance task is replacing the batteries: 1 Open the battery compartment (1) on the underside of the instrument. 2 Remove the four batteries from the battery compart- ment.

  • Page 32: Cleaning

    Maintenance, cleaning, disposal pH 720 Cleaning Occasionally wipe the outside of the measuring instrument with a damp, lint-free cloth. Disinfect the housing with iso- propanol as required. Caution The housing is made of synthetic material (ABS). Thus, avoid contact with acetone or similar detergents that contain solvents.

  • Page 33: What To Do If

    pH 720 What to do if... What to do if... Error message, Cause Remedy pH electrode: – Not connected – Connect electrode – Air bubbles in front of the – Remove air bubbles diaphragm – Air in the diaphragm – Extract air or moisten diaphragm –...
  • Page 34 What to do if... pH 720 Buffer solutions: – Incorrect buffer solutions – Change calibration procedure – Buffer solutions too old – Only use once. Note the shelf life – Buffer solutions depleted – Change solutions No stable Cause Remedy measured value pH electrode: –...
  • Page 35 You would like to Cause Remedy know which soft- – e.g. question of the WTW – Press the key and ware version is in service department switch on instrument. the instrument The software version...
  • Page 36 What to do if... pH 720...

  • Page 37: Technical Data

    pH 720 Technical Data Technical Data Storage temperature - 25 °C ... + 65 °C Ambient temperature Operating temperature 0 °C ... + 55 °C Allowable relative hu- Annual mean: < 75 % midity 30 days/year: 95 % Other days: 85 % - 2.000 ...
  • Page 38 Technical Data pH 720 Length [mm] Dimensions and weight Width [mm] Height [mm] Weight [kg] Approx. 0.850 Batteries 4 x 1.5 V AA type alkaline manganese Energy supply batteries Runtime Approx. 3000 operating hours Mains power Connection max. overvoltage category supply (option) II (valid for all plug-in power supplies): Plug-in power supply unit...
  • Page 39 pH 720 Technical Data FCC Class A Equipment Statement Note: This equipment has been tested and found to comply with the limits for a Class A digital device, pursuant to Part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference when the equipment is operated in a commercial environment.
  • Page 40 Technical Data pH 720...

  • Page 41: Lists

    pH 720 Lists Lists This chapter provides additional information and orientation aids. Abbreviations The list of abbreviations explains abbreviations that appear on the display or when dealing with the instrument. Specialist terms The glossary briefly explains the meaning of the specialist terms.
  • Page 42 Calibration Cd... Calibration with DIN buffer solutions (acc. to DIN 19 266) ConCal Conventional one/two point calibration Ct... Calibration with WTW technical buffer so- lutions Error message (see W ...) HAT TO DO IF Initialization Resets individual basic functions to...
  • Page 43 pH 720 Lists Slope Slope setting on calibration Temperature probe Temperature measurement active Asymmetry potential °C Temperature unit, °Celsius °F Temperature unit, Fahrenheit...
  • Page 44 Contact point between the reference electrolytic solution and the sample. Drift control See A ® MultiCal Group term for the various WTW calibration procedures used for automatic calibration in buffer solutions. Redox voltage Potentiometric quantity. Resolution Number of decimal places that appear for a measured val- Slope Specifies the voltage change per pH unit.
  • Page 45 pH 720 Lists Index asymmetry ....19 place of the instrument ..15 authorized use .
  • Page 46 Lists pH 720...
  • Page 48 Wissenschaftlich-Technische Werkstätten GmbH Dr.-Karl-Slevogt-Straße 1 D-82362 Weilheim Germany Tel: +49 (0) 881 183-0 +49 (0) 881 183-100 Fax: +49 (0) 881 183-420 E-Mail: Info@WTW.com Internet: http://www.WTW.com...

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