wtw Oxi 197i Operating Manual

AUTO READ CAL STO M RCL ON / OFF Oxi 197i mg/l O 7 1 7 6 92 °C ARng TP REL1 Portable oxygen measuring instrument

The use of advanced technology and the high quality standard of our instruments are the result of a continuous development. This may re- sult in differences between this operating manual and your instrument. Also, we cannot guarantee that there are absolutely no errors in this manual. Therefore, we are sure you will understand that we cannot ac- cept any legal claims resulting from the data, figures or descriptions. Copyright © Weilheim 2004, WTW GmbH Reproduction in whole - or even in part - is prohibited without the ex- press written permission of WTW GmbH, Weilheim. Printed in Germany.

3 1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 1.1 Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 1.2 Keypad . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 1.3 Socket field . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 2 Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 2.1 Authorized use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 2.2 General safety instructions . . . . . . . . . . . . . . . . . . . . . . . 10 3 Commissioning. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 3.1 Scope of delivery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 3.2 Power supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 3.3 Initial commissioning . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 3.4 Sensor quiver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 4 Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 4.1 Switching on the measuring instrument . . . . . . . . . . . . . 15 4.2 Measuring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 4.2.1 General information . . . . . . . . . . . . . . . . . . . . . . 16 4.2.2 Measuring the D. O. concentration . . . . . . . . . . 17 4.2.3 Measuring the D. O. saturation . . . . . . . . . . . . . 18 4.2.4 Automatic selection of the measuring range, AutoRange . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 4.2.5 AutoRead AR (drift control) and hold function . . 19 4.2.6 Sensor with stirrer (StirrOx G) . . . . . . . . . . . . . . 20 4.3 Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 4.3.1 Calibrating with the air calibration vessel . . . . . 23 4.3.2 Calibrating via a comparison measurement . . . 25 4.3.3 Entering the salt content (salinity) . . . . . . . . . . . 27 4.4 Saving . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 4.4.1 Saving manually . . . . . . . . . . . . . . . . . . . . . . . . 28 4.4.2 Saving automatically . . . . . . . . . . . . . . . . . . . . . 30 4.4.3 Outputting the data storage . . . . . . . . . . . . . . . . 32 4.4.4 Clearing the memory . . . . . . . . . . . . . . . . . . . . . 36 4.5 Transmitting data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 4.5.1 Data transmission interval (Int 2) . . . . . . . . . . . 37 4.5.2 Recorder (analog output) . . . . . . . . . . . . . . . . . 39 4.5.3 PC/external printer (RS232 interface) . . . . . . . . 40 4.5.4 Remote control . . . . . . . . . . . . . . . . . . . . . . . . . 40 4.6 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 4.7 Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 5 Maintenance, cleaning, disposal. . . . . . . . . . . . . . . . . 47 5.1 Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Oxi 197i 4 5.2 Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 5.3 Disposal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 6 What to do if... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 7 Technical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 7.1 General data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 7.2 Measuring ranges, resolutions, accuracies . . . . . . . . . . 55 8 Lists . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

oxygen measurements rapidly and reliably. The Oxi 197i provides the maximum degree of operating comfort, reli- ability and measuring certainty for all applications. The proven OxiCal® calibration procedure supports you in your work with the measuring instrument. The special AutoRead function enables precise measurements. 1 Keypad 2 Display 3 Integrated, exchangeable sensor quiver 4 Socket field 5 Carrying and positioning handle RUN / ENTER AUTO READ CAL STO M RCL ON / OFF Oxi 197i mg/l O 7 1 7 6 92 °C ARng TP REL1 1 2 3 4 5

following material from WTW: � Application reports � Primers � Safety datasheets. You will find information on available literature in the WTW catalog or via the Internet. 1.1 Display Sal pH mV/ m cm S/ cm 1/ pH nLF TEC Tref25 Tref20 REL2 REL1 Lin /K % Sal %mg/l S O 8 8 8 8 8 8 8 1 °C Time Year LoBat Oxi ARng AR RCL Ident Store TP No. Day.Month Baud Auto Cal Status display indicator Measured value Function and Temperature display Sensor symbol display

� Oxygen depth armature � D. O. sensor CellOx 325, or � D. O. sensor DurOx 325, or � Self-stirring D. O. sensor StirrOx G Connectors Warning Only connect sensors to the measuring instrument that cannot return any voltages or currents that are not allowed (> SELV and > current cir- cuit with current limiting). Nearly all sensors - especially WTW sensors - fulfill these conditions. Sensor / Instrument Socket Oxygen sensor 1 Integrated stirrer StirrOx G 2 Printer or PC (serial interface, RS232) 3 Plug-in power supply unit 4 Watertight valve for internal pressure equalization 5 2 1 3 4 5

during the commissioning, operation and maintenance of the measur- ing instrument . Consequently, all responsible personnel must read this operating manual before working with the measuring system. The op- erating manual must always be available within the vicinity of the mea- suring system. Target group The measuring instrument was developed for work in the field and in the laboratory. We assume that, as a result of their professional training and experi- ence, the operators will know the necessary safety precautions to take when handling chemicals. Safety instructions The individual chapters of this operating manual use safety instructions such as the label shown below to indicate various hazards or dangers: Warning indicates instructions that must be followed precisely in order to avoid the possibility of slight injuries or damage to the instrument or the envi- ronment. Further notes Note indicates notes that draw your attention to special features. Note indicates cross-references to other documents, e.g. operating manu- als. 2.1 Authorized use The authorized use of the measuring instrument consists exclusively of the measurement of the dissolved oxygen (D. O.) content of liquid me- dia in the field and laboratory. The technical specifications as given in chapter 7 TECHNICAL DATA must be observed. Only the operation and running of the measuring instru- ment according to the instructions given in this operating manual is au- thorized. Any other use is considered to be unauthorized.

This instrument is built and inspected according to the relevant guide- lines and norms for electronic measuring instruments (see chapter 7 TECHNICAL DATA). It left the factory in a safe and secure technical condition. Function and operating safety The smooth functioning and operational safety of the measuring instru- ment can only be guaranteed if the generally applicable safety mea- sures and the specific safety instructions in this operating manual are followed during operation. The smooth functioning and operational safety of the measuring instru- ment can only be guaranteed under the environmental conditions that are specified in chapter 7 TECHNICAL DATA. If the instrument was transported from a cold environment to a warm environment, the formation of condensate can lead to the faulty func- tioning of the instrument. In this event, wait until the temperature of the instrument reaches room temperature before putting the instrument back into operation. Safe operation If safe operation is no longer possible, the instrument must be taken out of service and secured against inadvertent operation! Safe operation is no longer possible if the measuring instrument: � has been damaged in transport � has been stored under adverse conditions for a lengthy period of time � is visibly damaged � no longer operates as described in this manual. If you are in any doubt, please contact the supplier of the instrument. Obligations of the purchaser The purchaser of the measuring instrument must ensure that the fol- lowing laws and guidelines are observed when using dangerous sub- stances: � EEC directives for protective labor legislation � National protective labor legislation � Safety regulations � Safety datasheets of the chemical manufacturers.

� Portable measuring instrument, Oxi 197i with integrated recharge- able battery � Carrying and positioning handle � Carrying strap � Sensor quiver � Plug-in power supply unit � Operating manual 3.2 Power supply Mains operation and charging the battery You can either operate the measuring instrument with the integrated re- chargeable battery or with the plug-in power supply. The plug-in power supply supplies the measuring instrument with low voltage (12 V DC). At the same time, the rechargeable battery is charged. Note The automatic stirring function of the self-stirring D. O. sensor StirrOx G can only be used when the plug-in power supply is connect- ed. Charging time of the battery approx. 16 hours. The battery is charged even when the instrument is switched off. The LoBat display indicator appears when the battery is nearly empty and has to be charged as soon as possible. Warning The line voltage at the operating site must lie within the input voltage range of the original plug-in power supply (see chapter 7 TECHNICAL DA- TA). Warning Use original plug-in power supplies only (see chapter 7 TECHNICAL DATA).

power supply unit 3.3 Initial commissioning Perform the following activities: � For mains operation and charging the battery: Connect the plug-in power supply (see section 3.2 POWER SUPPLY). � Set the date and time. Setting the date and time 1 Connect the plug (1) to the socket (2) of the measuring instru- ment. 2 Connect the original WTW plug-in power supply (3) to an easily accessible mains socket. 2 1 3 1 Press the key and hold it down. 2 Press the key. The display test appears briefly on the display. 3 Press the key repeatedly until the date flashes on the display (Day.Month display indicator).

5 Confirm with . The date (month) flashes in the display. 6 Set the current month with . 7 Confirm with . The year appears on the display. 8 Set the current year with . 9 Confirm with . The hours flash on the display. 10 Set the current time with . 11 Confirm with . The minutes flash on the display. 12 Set the current time with . 13 Confirm with . The instrument switches to the measuring mode. REL1 Tref25 5 t 2 Time Cal I O AR cm 1/ TP ARng nLF °C cm S/ Sal RCL % S % m mg/l Oxi Year Ident No. Tref20 LoBat Lin Sal pH TEC Auto Store Baud K / REL2 /pH mV Day.Month 0 9 0 4

ment moist, the quiver tip contains a sponge rubber insert that can be moistened with deionized water. Note For further details on proper storage, refer to the operating manual of the sensor. Moistening the quiver insert 1 Press the quiver out of the holder from the back side of the in- strument and pull it out completely. 2 Pull off the quiver tip and moisten the sponge rubber with deionized water.

Note The measuring instrument has an energy saving feature to avoid un- necessary battery depletion. The energy saving feature switches the measuring instrument off if no key has been pressed for an hour. The energy saving feature is not active when the AutoStore function is ac- tive. The energy saving feature is also not active � if the power is supplied by the plug-in power supply, � if the communication cable and a PC with a running communication program are connected, � if the recorder cable is connected, � if the printer cable is connected (for external printers). 1 Connect the D. O. sensor to the measuring instrument. 2 Press the key. The display test appears briefly on the display. The relative slope for the sensor type that was just connected subsequently appears for approx. one second. The measuring instrument then automatically switches to the measuring mode that was last selected. The display shows the relevant measured value.

� D. O. concentration � D. O. saturation The measuring instrument is supplied with the following functions: � AutoRange (automatic switchover of the measurement range). If a measuring range is exceeded, AutoRange causes the measuring in- strument to change automatically to the next higher measuring range and back again. Therefore, the instrument always measures in the measuring range with the highest possible resolution. The function can be switched off. � The AutoRead function (drift control) for checking the stability of the measurement signal. This ensures the reproducibility of the measur- ing signal. For details of how to switch the AutoRead function on/off, see page 19. Preparatory activities Perform the following preparatory activities when you want to measure: Note Incorrect calibration of D. O. sensors will result in incorrect measured values. Calibrate at regular intervals. Note The measuring instrument automatically recognizes the type of the D. O. sensor (CellOx 325 or DurOx 325). Temperature sensor The D. O. sensor has an integrated temperature sensor that always measures the current temperature of the test sample. Warning When connecting an earthed PC/printer, measurements cannot be per- formed in earthed media as incorrect values would result. The RS232 interface is not galvanically isolated. 1 Connect the D. O. sensor to the measuring instrument (see section 1.3 SOCKET FIELD). 2 Calibrate or check the measuring instrument with the D. O. sensor. How to calibrate is described in section 4.3. 3 Select the measuring mode with .

Note When measuring the concentration of test samples with a salt content of more than 1 g/l, a salinity correction is required. For this, you have to measure and input the salinity of the measured medium first. This is de- scribed in section 4.3.3 on page 27. Switching the salt content correction on or off, see below. To measure the D. O. concentration with and without salt content cor- rection, proceed as follows: Switching on/off the salt content correction Proceed as follows to switch on the salt content correction: 1 Perform the preparatory activities according to section 4.2.1. 2 Immerse the D. O. sensor in the test sample. 3 Press the key repeatedly until the D. O. concentration in mg/l appears on the display. REL1 Sal S pH AR 1 LoBat nLF Lin Oxi Tref25 Tref20 Cal TEC Auto Store 8 Time Year Ident No. Day.Month Baud 1/cm Sal /K % RCL REL2 /pH mV m %S/cm 7 1 7 6 9 2 °C TP O ARng mg/l 1 In the D. O. concentration measuring mode, switch on the salt content correction with . The SAL display indicator ap- pears on the display. The value that was entered is taken into consideration during the measurement (see section 4.3.3). 2 Switch the salt content correction off with . The SAL dis- play indicator is no longer displayed. REL1 Sal S pH AR 1 LoBat nLF Lin Oxi Tref25 Tref20 Cal TEC Auto Store 8 Time Year Ident No. Day.Month Baud 1/cm /K % RCL REL2 /pH mV m %S/cm 5 1 7 6 4 2 °C TP O ARng mg/l Sal

You can measure the D. O. saturation as follows: 4.2.4 Automatic selection of the measuring range, AutoRange Sensors You can use the sensors listed in section 1.3 on page 8. The sensor type is automatically recognized and the resolution is adjusted if nec- essary (see chapter 7 TECHNICAL DATA). AutoRange Two measuring ranges are available for each measuring mode. If a measuring range is exceeded, AutoRange causes the measuring in- strument to change automatically to the next higher measuring range and back again. Therefore, the instrument always measures in the measuring range with the highest possible resolution. To switch the automatic measurement range selection on/off, see section 4.6 CONFIGURATION. When the AutoRange function is switched on, ARng appears on the display. 1 Perform the preparatory activities according to section 4.2.1 2 Immerse the D. O. sensor in the test sample. 3 Press the key repeatedly until the saturation in % appears on the display. Sal REL1 mg/l / mV m Sal S pH AR 1 LoBat nLF Lin Oxi Tref25 Tref20 Cal TEC Auto Store 8 Time Year Ident No. Day.Month Baud 1/cm /K % RCL REL2 pH S/cm 8 1 7 6 9 2 °C TP O ARng % Sal S pH 1 LoBat nLF Lin Oxi Tref25 Tref20 Cal TEC Auto Store 8 Time Year Ident No. Day.Month Baud 1/cm Sal /K % RCL REL2 /pH mV m %S/cm 7 1 7 6 0 8 °C TP REL1 O ARng mg/l AR

The AutoRead function (drift control) checks the stability of the mea- surement signal. The stability has a considerable impact on the repro- ducibility of the measured values. With the aid of the hold function the measured value display is frozen. Criteria With identical measurement conditions, the following criteria are valid for the AutoRead function: Use the AutoRead function and hold function like this with the sensors � Oxygen depth armature � CellOx 325 � DurOx 325 Note The special features of the self-stirring D. O. sensor StirrOx G can be found in section 4.2.6 on page 20. Measuring mode Reproducibility Response time D. O. concentra- tion better than 0.05 mg/l > 10 seconds D. O. saturation index better than 0.6 % > 10 seconds 1 Select the measuring mode with . 2 Activate the AutoRead function with . The current mea- sured value is frozen (hold function). 3 Start AutoRead with . AR flashes until a stable measured value is reached. 4 If necessary, start the next AutoRead measurement with . REL1 Sal S pH 1 LoBat nLF Lin Oxi Tref25 Tref20 Cal TEC Auto Store 8 Time Year Ident No. Day.Month Baud 1/cm Sal /K % RCL REL2 /pH mV m %S/cm 7 1 7 6 0 8 °C TP O ARng mg/l AR

Connection Connect the 2-pole stirrer plug to the stirrer output of the measuring in- strument (designation REL1). Note The automatic stirring function of the self-stirring D. O. sensor StirrOx G can only be used when the plug-in power supply is connect- ed. Stirrer function The D. O. sensor, StirrOx G, has a temperature sensor and stirrer inte- grated. Using the key on the sensor you switch the stirrer on. Measuring with AutoRead You can switch on the stirrer and start an AutoRead measurement at the same time. To do so, proceed as follows: 5 To terminate the AutoRead function: Press the key. 1 Select the measuring mode with . 2 Activate the AutoRead function with . The current mea- sured value is frozen (hold function). 3 Submerse the sensor in the test sample and press the stirrer button. The stirrer is startet. At the same time, the AutoRead measurement starts. AR flashes until a stable measured value is achieved. Subsequently, the stirrer switches itself off. REL1 Sal S pH 1 LoBat nLF Lin Oxi Tref25 Tref20 Cal TEC Auto Store 8 Time Year Ident No. Day.Month Baud 1/cm Sal /K % RCL REL2 /pH mV m %S/cm 7 1 7 6 0 8 °C TP O ARng mg/l AR

tion determines the current slope of the sensor and stores this value in the instrument. Thus, you should calibrate at regular intervals. Calibration data records The Oxi 197i administrates two sets of calibration data: Sensors of different classes can be calibrated separately. When a sen- sor of one class is calibrated the calibration data of the other class re- main stored. The Oxi 197i recognizes the class of the connected sensor and automatically uses the correct calibration data. Calibration procedures The Oxi 197i provides 2 calibration procedures: � Calibration in water vapor-saturated air. To calibrate the CellOx 325, use theOxiCal®-SL air calibration ves- sel (accessory), to calibrate the DurOx 325, use the OxiCal®-D air calibration vessel (contained in the scope of delivery of the sensor). � Calibration via a comparison measurement (e. g. Winkler titration according to DIN EN 25813 or ISO 5813). At the same time, the rel- ative slope is adapted to the comparison measurement by a correc- tion factor. When to calibrate? � After connecting another D. O. sensor � If the sensor symbol flashes, i. e. after the calibration interval has ex- pired Calibration interval The calibration interval (Int 3) is set to 14 days in the factory. You can select the interval in the range of 1 ... 999 days. AutoRead The calibration procedure automatically activates the AutoRead func- tion. Displaying calibration data Each time the instrument is switched on, the calibration data are shown on the display for a short time (see section 4.1 SWITCHING ON THE MEA- SURING INSTRUMENT). In order to view the calibration data, switch the measuring instrument off and switch it on again. � Set 1, for sensor class 1: – Oxygen depth armature – CellOx 325, or – StirrOx G � Set 2, for sensor class 2: – DurOx 325

ibration. You can transmit the calibration protocol to a printer via the se- rial interface (see page 35). Note You can automatically print a calibration record after the calibration. To do so, connect a printer to the interface according to section 4.5.3 be- fore calibrating. After a valid calibration, the record is printed. Sample printout: Sensor evaluation After the calibration, the measuring instrument evaluates the current status of the sensor against the relative slope. The evaluation appears on the display. The relative slope has no effect on the measuring accu- racy. Low values indicate that the electrolyte will soon be depleted and the sensor will have to be regenerated. CALIBRATION PROTOCOL 02.03.02 14:19 Device No.: 12345678 CALIBRATION 02 Cal time: 02.03.02 / 14:19 Cal interval: 14d OxiCal Tauto AR Relative Slope: 0,88 Probe: +++ Display Relative slope S = 0.8 ... 1.25 S = 0.7 ... 0.8 S = 0.6 ... 0.7 E3 Eliminate the error according to chapter 6 WHAT TO DO IF... S < 0.6 or S > 1.25

Proceed as follows to calibrate the instrument: Note The sponge in the air calibration vessel must be moist (not wet). Follow the instructions in the OxiCal®-SL or DurOx 325 operating manual. 1 Connect the D. O. sensor to the measuring instrument. 2 Keep an air calibration vessel ready for use. 3 Put the D. O. sensor into the air calibration vessel. 4 Press the key repeatedly until O2 CAL appears. 5 Press the key. AutoRead is active, AR flashes. 6 As soon as a stable value is achieved, AR stops flashing. Cal- ibration is finished; the sensor symbol indicates the relative slope determined and the sensor evaluation (see page 22). REL1 S AR Year Ident No. Day.Month Tref25 Tref20 LoBat Lin nLF mg/l ARng Sal pH 1 TEC Auto Store 8 Time Baud 1/cm Sal /K % RCL REL2 /pH mV m %S/cm C 1 7 6 A L °C TP O Oxi Cal REL1 Year Ident No. Day.Month Tref25 Tref20 LoBat Lin nLF mg/l ARng Sal pH 1 TEC Auto Store 8 Time Baud 1/cm Sal /K % RCL REL2 /pH mV m %S/cm 0 1 7 6 8 8 °C TP O S AR Oxi Cal

take for error elimination. 7 Switch to the measuring mode with . REL1 Year Ident No. Day.Month Tref25 Tref20 LoBat Lin nLF mg/l ARng Sal pH 1 TEC Auto Store 8 Time Baud 1/cm Sal /K % RCL REL2 /pH mV m %S/cm 0 1 7 6 8 8 °C TP O S AR Oxi Cal

Proceed as follows to calibrate the instrument: 1 Connect the D. O. sensor to the measuring instrument. 2 Press the key repeatedly until O2 FAC appears. 3 Immerse the D. O. sensor in the calibrating solution. 4 Press the key. The AutoRead measurement begins. If the measured value is stable, the instrument displays the determined measured value and the correction factor of the relative slope (initial value = 1.000). 5 Remove the D. O. sensor from the calibrating solution. 6 Perform a comparison measurement, e. g. Winkler titration, with the calibrating solution (determine the nominal value). Leave the measuring instrument switched on until the nominal value is determined. 7 Set the displayed value on the measuring instrument to the nominal value with . This changes the related correc- tion factor of the relative slope. REL1 S AR Year Ident No. Day.Month Tref25 Tref20 LoBat Lin nLF mg/l ARng Sal pH 1 TEC Auto Store 8 Time Baud 1/cm Sal /K % RCL REL2 /pH mV m %S/cm F 1 7 6 A C °C TP O Oxi Cal TP REL1 S Year Ident No. Day.Month Tref25 Tref20 LoBat Lin nLF Sal pH 1 TEC Auto Store Time Baud 1/cm Sal /K % RCL REL2 /pH mV m %S/cm 4 0 0 0 4 2 °C O 1 AR ARng Oxi Cal mg/l

value units flashes. 8 Switch to the measuring mode with or . TP REL1 S Year Ident No. Day.Month Tref25 Tref20 LoBat Lin nLF Sal pH 1 TEC Auto Store Time Baud 1/cm Sal /K % RCL REL2 /pH mV m %S/cm 4 0 0 7 4 5 °C O 1 AR ARng Oxi Cal mg/l

A salt content correction is required in the oxygen concentration mea- surement of samples with a salt content of more than 1 g/l. To do this, you have to enter the salinity equivalent (the measured salinity) of the test sample (range 0.0 - 70.0) and to switch on the salinity correction. Entering the salt content Note How to switch on the salt content correction is described on page 17. Parameter Value range Salinity 0.0 ... 70.0 in steps of 0.1 1 Determining the salinity of the test sample (any method). 2 Press the key repeatedly until Sal appears on the dis- play. 3 Enter the salt content with . 4 Switch to the measuring mode with . REL1 TP Oxi Cal AR °C S Year Ident No. Day.Month Tref25 Tref20 LoBat Lin nLF Sal pH 1 TEC Auto Store 8 Time Baud 1/cm /K % RCL REL2 /pH mV m %S/cm 5 6 9 6 5 0 O mg/l Sal ARng

to 500 datasets. A complete data record consists of: � Storage location � Date/time � Measured value � Temperature � Temperature measuring procedure � ID number You can transmit measured values (data records) to the data storage in two ways: � Save manually � Switch on AutoStore (Int 1). 4.4.1 Saving manually You can transmit a measured value to the data storage as follows: 1 Press the key. The current number (location number No.) of the next free stor- age location appears under the current measured value on the display. 2 Confirm with . The display switches to entering the ID number. RCL REL1 2 5 °C TP Sal S pH AR 1 LoBat nLF Lin Oxi Tref25 Tref20 Cal TEC Auto 8 Time Year Ident Day.Month Baud 1/cm Sal /K % REL2 /pH mV m %S/cm 8 4 3 7 O mg/l ARng No. Store

pied. You have the following options: 3 Using , enter the required ID number (1 ... 999). 4 Confirm with . The instrument changes to the measuring mode. No. RCL REL1 2 5 °C TP Sal S pH AR 1 LoBat nLF Lin Oxi Tref25 Tref20 Cal TEC Auto 8 Time Year Day.Month Baud 1/cm Sal /K % REL2 /pH mV m %S/cm 8 2 3 7 O mg/l ARng Store Ident Saving the current measured value. The oldest measured value (storage location 1) will be overwritten by this Press Returning to the measuring mode without saving press any key Outputting the data storage see section 4.4.3 Clearing the memory see section 4.4.4

automatic save processes. After the fixed interval has expired, the current data record is transmit- ted to the storage and to the interface. Setting the save interval: The default setting for the save interval (Int 1) is OFF. By this, the AutoStore function is switched off. To switch the function on, set an interval (5 s, 10 s, 30 s, 1 min, 5 min, 10 min, 15 min, 30 min, 60 min): 1 Press the key and hold it down. 2 Press the key. Int 1 appears on the display. 3 Set the required interval between the saving procedures with . 4 Confirm with . The number of free memory locations appears on the display. 5 As soon as all of the 500 storage locations are occupied, AutoStore is terminated (Int 1 = OFF). If there are not enough storage locations available for your measurements: – Output and backup the data storage (see page 32) and – clear the memory (see page 36). REL1 pH Ident No. Time Cal d O AR cm 1/ Tref25 TP ARng nLF °C cm S/ Sal RCL % S % m mg/l Oxi Year Day.Month Tref20 LoBat Lin Sal TEC Baud K / REL2 /pH mV F 1 n t Store I F O Auto REL1 I pH Ident No. Time Cal O AR cm 1/ Tref25 TP ARng nLF °C cm S/ Sal RCL % S % m mg/l Oxi Year Day.Month Tref20 LoBat Lin Sal TEC Baud K / REL2 /pH mV E 9 4 9 Store E R Auto F

output the data storage. After the function is finished, the AutoStore function is continued. By this, however, temporal gaps in the recording of the measured values will occur. Switching off AutoStore Switch AutoStore off by: � setting the save interval (Int 1) to OFF, or � switching the measuring instrument off and then on again. 6 Confirm with . The prompt for the ID number appears on the display. 7 Set the required ID number with . 8 Confirm with . The instrument switches to the Oxi measuring mode and starts the measuring and saving process. AutoStore flashes on the display. REL1 9 4 9 R E F I pH No. Time Cal O AR cm 1/ Tref25 TP ARng nLF °C cm S/ Sal RCL % S % m mg/l Oxi Year Day.Month Tref20 LoBat Lin Sal TEC Baud K / REL2 /pH mV 1 Store Auto Ident

You can output the contents of the data storage: � Stored data on the display � Calibration data on the display � Stored data on the serial interface � Calibration protocol on the interface Outputting stored data on the display You can perform the following activities: 1 Press the key repeatedly until StO dISP appears on the display. 2 Press the key. A measured value appears on the display. The storage location of the data record is displayed for approx. 2 s, then the respective temperature appears. Display further elements of the data record (ID number, date, time, storage location) Press Advance one data record (storage location) Press Go back one data record (storage location) Press REL1 Store Auto Ident I pH No. Time Cal O AR cm 1/ Tref25 TP ARng nLF °C cm S/ Sal % S % m mg/l Oxi Year Day.Month Tref20 LoBat Lin Sal TEC Baud K / REL2 /pH mV o S T I S D RCL P Sal REL1 Sal S pH AR 1 LoBat nLF Lin Oxi Tref25 Tref20 Cal TEC Auto Store 8 Time Year Ident No. Day.Month Baud 1/cm /K % REL2 /pH mV m %S/cm 6 2 4 7 0 3 °C TP O ARng mg/l RCL

lows: Outputting stored data to the interface Note You can cancel the transmission with or . After the instrument number, the printout contains the complete storage contents in ascending order of the storage location numbers. 1 Using , select the element (e.g. date). 2 Press or repeatedly until the required date appears on the display. After approx. 2 s the temperature of the displayed measured value appears. 1 Press the key repeatedly until Sto SEr appears on the display. 2 Press the key. The complete storage content is transmitted to the interface; during the data transmission the numbers of the currently transmitted storage locations run through. After the data trans- mission, the measuring instrument automatically switches to the measuring mode. REL1 D Store Auto Ident I pH No. Time Cal O AR cm 1/ Tref25 TP ARng nLF °C cm S/ Sal % S % m mg/l Oxi Year Day.Month Tref20 LoBat Lin Sal TEC Baud K / REL2 /pH mV o S T E S RCL r

Device No.: 99990000 No. 1: 09.03.02 17:10 101.7 % 17.6° C Tauto AR Ident : 10 No. 2: 09.03.02 17:11 7.11 mbar 17.6° C Tauto AR Ident : 10 No. 3: 09.03.02 17:12 7.88 mg/l 17.6° C Tauto Ident : 10 No. 4: 09.03.02 17:15 7.11 mg/l 17.8° C Tauto SAL = 17.9 Ident : 7 ... 1 Press the key repeatedly until CAL dISP appears on the display. 2 Press the key. The relative slope appears on the display: REL2 RCL REL1 Sal mg/l ARng O TP Oxi Cal AR °C S Year Ident No. Day.Month Tref25 Tref20 LoBat Lin nLF Sal pH C TEC Auto Store Time Baud 1/cm /K % /pH mV m %S/cm C I S P A L d mV Oxi TEC Auto pH pH / TP 1/cm Sal % /K °C Year Ident 1 Store AR LoBat nLF Lin Tref25 Tref20 ARng 8 Time No. Day.Month Baud REL2 m S/cm %mg/l Sal 8 8 REL1 Cal S L RCL 0 S O 0

Note You will find a sample calibration protocol in PRINTING THE CALIBRATION RECORD, page 22. 3 Using or , you can switch back to the measuring mode. 1 Press the key repeatedly until CAL SEr appears on the display. 2 Press the key. The calibration protocol is transmitted to the interface. After the data transmission, the measuring instrument auto- matically switches to the measuring mode. REL2 TP AR /K % REL1 d Sal mg/l ARng O Oxi Cal °C S Year Ident No. Day.Month Tref25 Tref20 LoBat Lin nLF Sal pH C TEC Auto Store Time Baud cm 1/ /pH mV m %S/cm C S E R A L RCL

With this function, you can delete the stored data records. 500 storage locations will then be available again. Note The Clear memory function only appears when there are data records stored in the memory. Otherwise, the measuring instrument automati- cally switches to the measuring mode. Proceed as follows to clear all data records: Note The calibration data remain stored and can be called up. 1 Switch off the measuring instrument. 2 Press the key and hold it down. 3 Press the key. The display test appears briefly on the display. Subsequently, Sto CLr appears. 4 Confirm the clearing process with . Pressing any other key prevents the clearing, the data records will remain stored. REL1 RCL d Sal mg/l ARng O TP Oxi Cal AR °C S Year Ident No. Day.Month Tref25 Tref20 LoBat Lin nLF Sal pH C TEC Auto Time Baud 1/cm /K % REL2 /pH mV m %S/cm S C L R T o Store

� One of the following options: – With the AutoStore function (page 30), measured values are periodically saved internally (save interval Int 1) and output on the interface. – With the Data transmission interval function (Int 2), measured values are periodically output on the interface (see below). � With the Output data storage function (page 32), calibration data or saved measured values are output on the interface. � Via the analog recorder output (page 39), measured values are out- put as voltage values. � With the KOM pilot communication kit (accessory), data can be transmitted bidirectionally (page 40). Note If you connect a recorder (analog output), the output on the digital in- terface is switched off. 4.5.1 Data transmission interval (Int 2) The interval for the data transmission (Int 2) determines the chronolog- ical interval between automatic data transmissions. After the selected interval expires, the current data record is transmitted to the interface. Note When the AutoStore function is active, the data transmission is per- formed according to the setting of the save interval (Int 1). Set the save interval (Int 1) to OFF to activate the Data transmission interval (Int 2).

To start the data transmission, set an interval (5 s, 10 s, 30 s, 1 min, 5 min, 10 min, 15 min, 30 min, 60 min): 1 Press the key and hold it down. 2 Press the key. Int 2 appears on the display. 3 Set the required interval between the saving procedures with . 4 Confirm with . The measuring instrument automatically switches to the mea- suring mode. REL1 Store RCL d Sal mg/l ARng O TP Oxi Cal AR °C S Year Ident No. Day.Month Tref25 Tref20 LoBat Lin nLF Sal pH TEC Auto Time Baud 1/cm /K % REL2 /pH mV m %S/cm n O F F T 2 I

You can transmit data to a recorder via the analog output. Connect the analog output to the recorder via the AK323 interface cable. The data output automatically switches to Recorder output. Socket assignment Note The analog output is activated automatically in the cable by connecting 2 and 3. Signal range The signal range of the analog output depends on the measured vari- able and the measuring range: Concentration Saturation 1 free 2 Plug coding 3 Ground 4 Analog output 1 2 3 4 RS 232 REC (internal resistance < 5 Ohm) Measuring range Voltage Resolution 0 ... 19.99 mg/l 0 ... 1999 mV 0.01 mg/l per 1 mV 0 ... 90.0 mg/l 0 ... 900 mV 0.1 mg/l per 1 mV Measuring range Voltage Resolution 0 ... 199.9 0 ... 1999 mV 0.1 % per 1 mV 0 ... 600 % 0 ... 600 mV 1 % per 1 mV

Via the RS 232 interface, you can transmit the data to a PC or an ex- ternal printer. Use the AK340/B (PC) or AK325/S (ext. printer) cable to connect the interface to the devices. The data output automatically switches to the RS232 interface. Warning The RS232 interface is not galvanically isolated. When connecting an earthed PC/printer, measurements cannot be per- formed in earthed media as incorrect values would result. Set up the following transmission data at the PC/printer: Socket assignment 4.5.4 Remote control The measuring instrument can be remotely controlled from a PC. This requires the KOM pilot communication kit. It is available as an acces- sory. The instrument is then controlled via commands that simulate key- strokes and request the current display contents. Note A more detailed description is provided within the scope of delivery of the communication kit. Baud rate selectable between: 1200, 2400, 4800, 9600 Handshake RTS/CTS + Xon/Xoff Parity none Data bits 8 Stop bits 1 1 CTS 2 RxD 3 Ground 4 TxD 1 2 3 4 RS 232 REC

ments. To do this, the following parameters can be changed (the status on delivery is marked in bold): Note You can leave the configuration menu at any time with . The pa- rameters that have already been changed are stored. Baud rate Baud rate 1200, 2400, 4800, 9600 Air pressure display Current value in mbar (no input possible) Calibration interval (Int 3) 1 ... 14 ... 999 d AutoRange ARng On or off Date/time Any 1 Switch off the measuring instrument. 2 Press the key and hold it down. 3 Press the key. The display test appears briefly on the display. The measuring instrument then switches automatically to the setting of the baud rate. 4 Select the required baud rate with . 5 Confirm with . On the display, the current air pressure in mbar appears. REL1 Store RCL Sal mg/l ARng O TP Oxi Cal AR °C S Year Ident No. Day.Month Tref25 Tref20 LoBat Lin nLF Sal pH TEC Auto Time 1/cm /K % REL2 /pH mV m S/cm % 8 0 0 4 Baud

measurement range 6 Confirm with . Int 3 appears on the display. REL1 RCL Cal TEC d Auto C A pH pH / Sal mg/l ARng O TP Oxi AR °C S Year Ident No. Day.Month Tref25 Tref20 LoBat Lin nLF SalC Store Time Baud 1/cm /K % REL2 mV m S/cm % 9 4 9 P 7 Set the required interval in days (d) with . 8 Confirm with . ARng appears on the display. AR cm 1/ 4 Tref25 TP ARng nLF °C cm S/ Sal RCL % S % m mg/l Oxi Year Ident No. Day.Month Tref20 LoBat Lin Sal pH TEC Auto Store Baud K / REL2 /pH mV 1 4 3 n t REL1 d I O Time Cal 9 Using , switch between no and YES. YES: Switch on AutoRange. no: Switch off AutoRange. 10 Confirm with . The date (day) flashes in the display. I Time d Cal TEC pH REL1 AR cm 1/ Tref25 TP nLF °C cm S/ Sal RCL % S % m mg/l Oxi Year Ident No. Day.Month Tref20 LoBat Lin Sal Auto Store Baud K / REL2 /pH mV S n A R E y ARng O

11 Set the date of the current day with . 12 Confirm with . The date (month) flashes in the display. 13 Set the current month with . 14 Confirm with . The year appears on the display. 15 Set the current year with . 16 Confirm with . The hours flash on the display. 17 Set the current time with . 18 Confirm with . The minutes flash on the display. 19 Set the current time with . 20 Confirm with . The measuring instrument automatically switches to the mea- suring mode. REL1 Tref25 5 t 2 Time Cal I O AR cm 1/ TP ARng nLF °C cm S/ Sal RCL % S % m mg/l Oxi Year Ident No. Tref20 LoBat Lin Sal pH TEC Auto Store Baud K / REL2 /pH mV Day.Month 0 9 0 4

uration parameters separately from one another. Measurement parameters The following measured parameters (O2 InI) are reset to the default condition: Note The calibration data gets lost when the measuring parameters are re- set. Recalibrate after performing a reset. Configuration parameters The following configuration parameters (InI) are reset to the delivery status: Measuring mode D. O. concentration AutoRange automatic measure- ment range selection On (YES) Relative slope 1.00 Correction factor of the relative slope 1.000 Salinity equivalent 0.0 Salinity correction Off Baud rate 4800 Interval 1 (automatic saving) OFF Interval 2 (for data transmission) OFF

tion parameters 1 Press the key and hold it down. 2 Press the key. 3 Using , switch between no and YES. YES: Resetting the measuring parameters no: Retaining settings. 4 Confirm with . The measuring instrument switches to the configuration pa- rameters. REL1 pH Day.Month 0 9 Tref25 Time Cal I AR cm 1/ TP ARng nLF °C cm S/ Sal RCL % S % m mg/l Oxi Year Ident No. Tref20 LoBat Lin Sal TEC Auto Store Baud K / REL2 /pH mV n o i in O 5 Using , switch between no and YES. YES: Resetting the configuration parameters no: Retaining settings. 6 Confirm with . The measuring instrument automatically switches to the mea- suring mode. REL1 O pH Day.Month 0 9 Tref25 Time Cal I AR cm 1/ TP ARng nLF °C cm S/ Sal RCL % S % m mg/l Oxi Year Ident No. Tref20 LoBat Lin Sal TEC Auto Store Baud K / REL2 /pH mV n o i in

47 5 Maintenance, cleaning, disposal 5.1 Maintenance The measuring instrument is maintenance-free. 5.2 Cleaning Occasionally wipe the outside of the measuring instrument with a damp, lint-free cloth. Disinfect the housing with isopropanol as re- quired. Warning The housing components are made out of synthetic materials (polyurethane, ABS and PMMA). Thus, avoid contact with acetone and similar detergents that contain solvents. Remove any splashes imme- diately. 5.3 Disposal Packing This measuring instrument is sent out in a protective transport packing. We recommend: Keep the packing material. The original packing pro- tects the measuring instrument from transport damages. Rechargeable battery Remove the rechargeable battery from the instrument and dispose of it at a suitable facility according to local legal requirements. It is illegal to dispose of the rechargeable battery with household refuse. Proceed as follows to disassemble the rechargeable battery: Ni-Cd Cd 1 Remove the carrying and positioning handle or the carrying strap. 2 Unscrew the fixing elements (1) using a hexagon key. 3 Remove the instrument from the enclosure by vigorously pressing against the socket field. 4 Take out the rechargeable battery (2) and cut off the battery ca- ble. 1 1 2

Oxi 197i 48 Measuring instrument, Dispose of the measuring instrument without the rechargeable battery as electronic waste at an appropriate collection point.

49 6 What to do if... Display LoBat Instrument does not react to keystroke Error message 0FL 0FL 0FL 0FL Error message E3 E3 E3 E3 Cause Remedy – Battery almost empty – Charge the battery (see section 3.2) Cause Remedy – Operating condition undefined or EMC load unallowed – Processor reset: Press the and keys at the same time and release them again. The software version is displayed. Cause Remedy Display range exceeded Oxygen sensor: – Not connected – Connect the sensor – Cable broken – Replace sensor – Depleted – Replace sensor – Short-circuit between gold and lead electrode – Clean sensor and replace it if necessary Cause Remedy Invalid calibration Oxygen sensor: – Electrolyte solution depleted – Regenerate sensor – Membrane contaminated – Clean membrane – Electrode system poisoned – Regenerate sensor – Obsolete – Replace sensor – Broken – Replace sensor

Oxi 197i 50 Error message E7 E7 E7 E7 AR flashes continuously Measured value too low Measured value too high Display to to to to Sensor symbol flashes Cause Remedy Membrane damaged – Membrane damaged – Regenerate sensor – Membrane head not screwed on tight enough – Screw membrane head tight Cause Remedy No stable measured value – Membrane contaminated – Clean membrane Cause Remedy – Insufficient flow – Provide flow to the sensor Cause Remedy – High amount of dissolved substances – Correct solubility function using the salinity equivalent – Air bubbles bump on the membrane with high velocity – Avoid direct flow to the membrane – The carbon dioxide pressure is too high (> 1 bar) – Measuring not possible Cause Remedy – Time-out of the interface – Check the instrument connected Cause Remedy – Calibration interval expired – Recalibrate the measuring system

51 Message StoFull StoFull StoFull StoFull You want to know which software version is in the instrument Cause Remedy – All memory locations are full – Output data storage and clear data storage Cause Remedy – E. g., a question by the WTW service department – Simultaneously press the and keys and release them again. The software version is displayed.

Weight approx. 1.5 kg (without plug-in power supply) Mechanical structure Type of protection: IP 67 Electrical safety Protective class: III Ambient conditions Power supply Operation -10 °C ... + 55 °C Storage - 25 °C ... + 65 °C Climatic class 2 Rechargeable battery Nickel-cadmium (NiCad) rechargeable battery Operational life approx. 600 hours with one charging Plug-in power supply unit (charging device) The following applies to all plug-in power supplies: Connection max. Overvoltage category II Euro plug FRIWO FW1199, 11.7864 Friwo Part. No. 1762613 Input: 230 V ~ / 50 Hz / 5.6 VA Output: 12 V = / 130 mA / 1.56 VA US plug FRIWO FW1199, 11.7880 Friwo Part. No. 1794043 Input: 120 V ~ / 60 Hz / 6 VA Output: 12 V = / 150 mA UK plug FRIWO FW1199, 11.7872 Friwo Part No. 1816491 Input: 230V ~ / 50 Hz / 5.6 VA Output: 12 V = / 130 mA / 1.56 VA

AK 340/B or AK 325/S. Analog output Automatic switchover when the recorder is connected by the cable, AK 323. Type RS232, data output Baud rate Can be set to 1200, 2400, 4800, 9600 Baud Data bits 8 Stop bits 2 Parity None Handshake RTS/CTS + Xon/Xoff Cable length Max. 15m Variable Voltage Resolution Saturation [%] / Range 0 ... 200.0 % 0 ... 600 % 0 ... 2 V 0 ... 600 mV ± 0.1 ± 1 Concentration [mg/l] / Range 0...20.00 mg/l 0...100.0 mg/l 0 ... 2 V 0 ... 1 V 0.01 mg/l 0.1 mg/l Accuracy ± 0.5 % of display value ± 0.1(% saturation) or ± 0.5 % of the display value ± 0.01 mg/l Internal resistance < 5 Ohm (current limited to max. 0.2 mA out- put current)

7.2 Measuring ranges, resolutions, accuracies Measuring ranges, resolutions Note: The values given in brackets apply to the sensor DurOx 325 es- pecially. Accuracy (± 1 digit) Correction functions EMC E.C. guideline 89/336/EEC EN 61326-1:1997 EN 61000-3-2 A14:2000 EN 61000-3-3:1995 FCC Class A Instrument safety E.C. guideline 73/23/EEC EN 61010-1 A2:1995 Climatic class VDI/VDE 3540 IP protection EN 60529:1991 Variable Measuring range Resolution Concentration [mg/l] 0 ... 19.99 (0 ... 19.9) 0 ... 90.0 (0 ... 90) 0.01 (0.1) 0.1 (1) Saturation [%] 0 ... 199.9 (0 ... 199) 0 ... 600 0.1 (1) 1 T [°C] 0 ... 50.0 0.1 Variable Accuracy Concentration [mg/l] ± 0.5 % of measured value at ambient temperature of + 5 °C ... + 30 °C Saturation [%] ± 0.5 % of measured value when measuring in the range of ± 10 K around the calibration temperature T [°C] ± 0.1 Temperature com- pensation Accuracy better than 2 % at 0 ... + 40 °C Salinity correction 0 ... 70.0 SAL Air pressure correc- tion Automatic through integrated pressure sensor in the range of 500 ... 1100 mbar

Abbreviations The list of abbreviations explains the indicators and the abbreviations that appear on the display and in the manual. Specialist terms The glossary briefly explains the meaning of the specialist terms. How- ever, terms that should already be familiar to the target group are not described here. Index The index helps you to find the topics that you are looking for.

ARng Automatic range switching Measuring instrument measures with highest reso- lution °C Temperature unit, degrees Celsius Cal Calibration E3 Error message see chapter 6 WHAT TO DO IF... InI Initialization Resets individual basic functions to the status they had on delivery LoBat Battery almost empty (Low Battery) OFL Display range exceeded (Overflow) OxiCal Automatic calibration for D. O. measurements SAL Salinity SELV Safety Extra Low Voltage TP Temperature measurement active (Temperature Probe)

displayed value) differs as little as possible from the correct value or a value that is regarded as correct, or that the difference remains with- in the tolerance. Amperometry Name of a measuring technique. The signal (depending on the mea- sured parameter) of the sensor is the electric current. The electrical voltage remains constant. AutoRange Name of the automatic selection of the measuring range. AutoRead WTW name for a function to check the stability of the measured value. Calibration Comparing the value from a measuring system (e. g. the displayed value) to the correct value or a value that is regarded as correct. Of- ten, this expression is also used when the measuring system is adjust- ed at the same time (see adjusting). D. O. partial pressure Pressure caused by the oxygen in a gas mixture or liquid. Measured parameter The measured parameter is the physical dimension determined by measuring, e. g. pH, conductivity or D. O. concentration. Measured value The measured value is the special value of a measured parameter to be determined. It is given as a combination of the numerical value and unit (e. g. 3 m; 0.5 s; 5.2 A; 373.15 K). Measuring system The measuring system comprises all the devices used for measuring, e. g. measuring instrument and sensor. In addition, there is the cable and possibly an amplifier, terminal strip and armature. Molality Molality is the quantity (in Mol) of a dissolved substance in 1000 g sol- vent. OxiCal® WTW name for a procedure to calibrate D. O. measuring systems in water vapor saturated air. Oxygen saturation Short name for the relative D. O. saturation. Note: The D. O. saturation value of air-saturated water and the D. O. saturation value of oxygen-saturated water are different. Reset Restoring the original condition of all settings of a measuring system. Resolution Smallest difference between two measured values that can be dis- played by a measuring instrument.

of the mass of dissolved salts to the mass of the solution (in g/Kg). In practice, this dimension cannot be measured directly. Therefore, the practical salinity is used for oceanographic monitoring. It is deter- mined by measuring the electrical conductivity. Salt content General designation for the quantity of salt dissolved in water. Sample Designation of the sample ready to be measured. Normally, a test sample is made by processing the original sample. The test sample and original sample are identical if the test sample was not processed. Slope The slope of a linear calibration function. Slope (relative) Designation used by WTW in the D. O. measuring technique. It ex- presses the relationship of the slope value to the value of a theoretical reference sensor of the same type of construction. Standard solution The standard solution is a solution where the measured value is known by definition. It is used to calibrate a measuring system.

Authorized use 9 AutoRange 18 AutoRead 19 Criteria 19 B Batteries Charging 11 Battery Charging time 11 C Calibration start 23 Calibration record 22 Connecting a printer 40 D Data record 28 Data transmission (interval) 38 Default condition 44 Display 6 Displaying calibration data 21 Drift control 19 E Electrode evaluation 22 Energy saving feature 15 Error messages 49 I Initial commissioning 12, 14 Initialization 44 Interval data transmission 37 save 30 K Keys 7 L LoBat 49 M Mains operation 11 Measuring range selection 18 Measuring the D. O. concen- tration 17 Measuring the D. O. satura- tion 18 O Operating safety 10 P Plug-in power supply 11 Printing calibration protocol 22 R Remote control 40 Reset 44 RS232 interface 40 S Safety 9 safety precautions 9 Salt content correction entering the salinity 27 switching on 17 Save interval 30 Scope of delivery 11 Setting the baud rate 41 Setting the date 12, 14, 43 Setting the time 12, 43 Slope 21 T Temperature sensor 16

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