Xylem MULTI-1970I User Manual

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Multi 1970i

AUTO READ

RUN / ENTER

Multi 1970i

CAL

1 7 6

RCL

STO

Operating manual

Multi 1970i

Portable pH / oxygen / conductivity measuring instrument

ba75693e01 01/2007

Accuracy when

going to press

The use of advanced technology and the high quality standard of our instruments are the result of a continuous development. This may result 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 accept any legal claims resulting from the data, figures or descriptions.

Reproduction in whole - or even in part - is prohibited without the express written permission of WTW GmbH, Weilheim. Printed in Germany.

Multi 1970i List of contents

1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

1.1 General features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

1.2 Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

1.3 Keypad . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

1.4 Jack field . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

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 Operating structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

4.2 Switching on the measuring instrument . . . . . . . . . . . . . 16

4.3 pH value / ORP voltage . . . . . . . . . . . . . . . . . . . . . . . . . 17

4.3.1 General information . . . . . . . . . . . . . . . . . . . . . . 17

4.3.2 Measuring the pH value . . . . . . . . . . . . . . . . . . 19

4.3.3 Measuring the ORP voltage . . . . . . . . . . . . . . . 20

4.3.4 pH calibration . . . . . . . . . . . . . . . . . . . . . . . . . . 21

4.4 Dissolved oxygen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

4.4.1 General information . . . . . . . . . . . . . . . . . . . . . . 27

4.4.2 Measuring the D. O. concentration . . . . . . . . . . 29

4.4.3 Measuring the D. O. saturation . . . . . . . . . . . . . 30

4.4.4 AutoRead AR (Drift control) and hold function . 31

4.4.5 D. O. calibration . . . . . . . . . . . . . . . . . . . . . . . . 32

4.4.6 Entering the salt content (salinity) . . . . . . . . . . . 35

4.5 Conductivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

4.5.1 General information . . . . . . . . . . . . . . . . . . . . . . 36

4.5.2 Measuring the conductivity . . . . . . . . . . . . . . . . 38

4.5.3 Measuring the salinity . . . . . . . . . . . . . . . . . . . . 38

4.5.4 AutoRead AR (Drift control) and hold function . 39

4.5.5 Determining the cell constant (Calibration in the

control standard) . . . . . . . . . . . . . . . . . . . . . . . . 40

4.6 Calibration intervals (Int 3, Int 4, Int 5) . . . . . . . . . . . . . . 43

4.7 Saving data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

4.7.1 Saving manually . . . . . . . . . . . . . . . . . . . . . . . . 44

4.7.2 Switching on AutoStore (Int 1) . . . . . . . . . . . . . 46

4.7.3 Outputting the data storage . . . . . . . . . . . . . . . . 48

4.7.4 Clearing the memory . . . . . . . . . . . . . . . . . . . . . 54

4.8 Transmitting data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

List of contents Multi 1970i

4.8.1 Data transmission interval (Int 2) . . . . . . . . . . . . 55

4.8.2 PC/external printer (RS232 interface) . . . . . . . . 57

4.8.3 Remote control . . . . . . . . . . . . . . . . . . . . . . . . . 57

4.9 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

4.10 Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

5 Maintenance, cleaning, disposal . . . . . . . . . . . . . . . . . 65

5.1 Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

5.2 Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

5.3 Disposal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

6 What to do if... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

6.1 pH system messages . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

6.2 Oxi system messages . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

6.3 Conductivity system messages . . . . . . . . . . . . . . . . . . . 70

6.4 General errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

7 Technical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

7.1 General data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

7.2 Measuring ranges, resolutions, accuracies . . . . . . . . . . 74

7.2.1 pH/ORP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

7.2.2 Dissolved oxygen . . . . . . . . . . . . . . . . . . . . . . . . 75

7.2.3 Conductivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

8 Lists . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77

Multi 1970i Overview

RUN / ENTER

Multi 1970i

1Overview

1.1 General features

The Multi 1970i portable multiparameter measuring instrument enables you to carry out pH measurements, dissolved oxygen (D. O.) measurements and conductivity measurements quickly and reliably. The Multi 1970i provides the maximum degree of operating comfort, reliability and measuring certainty for all applications.

The proven MultiCal

and OxiCal® calibration procedures and the procedures to determine/set up the cell constant support you in your work with the meter. The special AutoRead function enables precise measurements.

ON / OFF

AUTO READ

RUN / ENTER

CAL

1 7 6

RCL

STO

Multi 1970i

1 Keypad

2 Display

3 Integrated, exchangeable sensor quiver

4 Jack field

5 Carrying and positioning handle

Overview Multi 1970i

Note

If you need further information or application notes, you can obtain the following material from WTW:

z Application reports

z Primers

z Safety datasheets.

You will find information on available literature in the WTW catalog or via the Internet.

1.2 Display

Status display indicator

Sal

Time

Day.Month

Year

LoBat nLF

Baud

No.

Ident

8 8 8 8

Tref25 Tref20

Lin

Auto

Oxi

Cal

Store

TEC

ARng

REL1

pHmV/

mg/l

REL2

Sal

RCL

Sensor symbol

Measured value display

Function and temperature display

Multi 1970i Overview

RCL

STO

1.3 Keypad

Key functions

ON / OFF

CAL

AUTO READ

RUN / ENTER

Calibrate the currently set measured variable

Switch measuring instrument on/off

Select the measured variable <M>:

– pH value / ORP voltage

– D. O. concentration / D. O. saturation

– Conductivity / salinity

<CAL>

Activate/deactivate the AutoRead function

Confirm entries, start AutoRead, output measured values

Select the measuring mode, increase values, scroll

<▲ >

Select the measuring mode, decrease values, scroll

<▼ >

RCL

STO

Display/transmit measured values

<RCL>

Save a measured value

<STO>

1.4 Jack field

Warning

Only connect sensors to the measuring instrument that cannot return any voltages or currents that are not allowed (> SELV and > current circuit with current limiting). Almost all sensors - in particular WTW sensors - fulfill these conditions.

Overview Multi 1970i

Maximum number

of sensors to be con-

nected

Connectors:

The following sensors can be connected to the Multi 1970i (maximum configuration):

z One pH depth armature or

one pH electrode (combination electrode or pH electrode + reference electrode). Please make sure that only one pH sensor is connected at the same time.

z One D. O. sensor

z One conductivity measuring cell

z Option: One external temperature sensor

Note

The pH depth armature is affected by other sensors if it is connected to them galvanically. For this reason, the pH depth armature cannot be operated in the same test sample together with another sensor on the instrument.

Sensor / Instrument Socket / Posi-

tion

pH depth armature 1

pH electrode or pH combination electrode 2

pH combination electrode with temperature sensor 2 and 4

Reference electrode 3

Temperature sensor, external 3 and 4

Oxygen sensor 5 or 6

Conductivity measuring cell 5 or 6

Printer or PC (serial interface, RS232) 7

Plug-in power supply unit 8

Watertight valve for internal pressure equalization 9

Multi 1970i Overview

Note

The sensor sockets, 1 and 2 must not be assigned at the same time. On the two sockets, 5 and 6, only different sensor types (Oxi and Cond) may be connected at the same time.

Overview Multi 1970i

Multi 1970i Safety

2 Safety

This operating manual contains basic instructions that you must follow during the commissioning, operation and maintenance of the measuring instrument. Consequently, all responsible personnel must read this operating manual before working with the measuring system. The operating manual must always be available within the vicinity of the measuring system.

Target group The measuring instrument was developed for work in the field and in

the laboratory. Thus, we assume that, as a result of their professional training and experience, the operators will know the necessary safety precautions to take when handling chemicals.

Safety instructions The individual chapters of this operating manual use the following safe-

ty instruction to indicate various types of danger:

Warning

indicates instructions that must be followed precisely in order to avoid the possibility of slight injuries or damage to the instrument or the environment.

Further notes

Note

indicates notes that draw your attention to special features.

Note

indicates cross-references to other documents, e.g. operating manuals.

2.1 Authorized use

The authorized use of the measuring instrument consists exclusively of the:

z pH and ORP measurement

z measurement of the oxygen content and

z measurement of the conductivity, salinity and temperature

in the field and laboratory.

The technical specifications as given in chapter 7 T must be observed. Only the operation and running of the measuring instrument according to the instructions given in this operating manual is authorized. Any other use is considered to be unauthorized.

ECHNICAL DATA

Safety Multi 1970i

2.2 General safety instructions

This instrument is built and inspected according to the relevant guidelines and norms for electronic measuring instruments (see chapter 7T

ECHNICAL DATA).

It left the factory in a safe and secure technical condition.

Function and operating

safety

Safe operation If safe operation is no longer possible, the instrument must be taken out

The smooth functioning and operational safety of the measuring instrument can only be guaranteed if the generally applicable safety measures and the specific safety instructions in this operating manual are followed during operation.

The smooth functioning and operational safety of the measuring instrument can only be guaranteed under the environmental conditions that are specified in chapter 7 T

ECHNICAL DATA.

If the instrument was transported from a cold environment to a warm environment, the formation of condensate can lead to the faulty functioning of the instrument. In this event, wait until the temperature of the instrument reaches room temperature before putting the instrument back into operation.

of service and secured against inadvertent operation! Safe operation is no longer possible if the measuring instrument:

z has been damaged in transport

z has been stored under adverse conditions for a lengthy period of

time

Obligations of the pur-

chaser

z is visibly damaged

z no longer operates as described in this manual.

If you are in any doubt, please contact the supplier of the instrument.

The purchaser of the measuring instrument must ensure that the following laws and guidelines are observed when using dangerous substances:

z EEC directives for protective labor legislation

z National protective labor legislation

z Safety regulations

z Safety datasheets of the chemical manufacturers.

Multi 1970i Commissioning

3 Commissioning

3.1 Scope of delivery

z Multi 1970i portable multiparameter measuring instrument with inte-

grated rechargeable battery

z Carrying and positioning handle

z Carrying strap

z 2 sensor quivers (pH and Oxi-LF type)

z Plug-in power supply unit

z Operating manual

3.2 Power supply

Mains operation and

charging the battery

Charging time of the

battery

You can either operate the measuring instrument with the integrated rechargeable 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.

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 T

TA).

ECHNICAL DA-

Warning

Use original plug-in power supplies only (see chapter 7 T

ECHNICAL DATA).

Commissioning Multi 1970i

Connecting the plug-in

power supply unit

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.

3.3 Initial commissioning

Perform the following activities:

z For mains operation and charging the battery: Connect the plug-in

power supply (see section 3.2 P

z Set the date and time.

1 Press the <M> key and hold it down.

2 Press the <ON/OFF> key.

The display test appears briefly on the display.

3 Press the <RUN/ENTER> key repeatedly until the date flashes

on the display (Day.Month display indicator).

OWER SUPPLY).

Multi 1970i Commissioning

mg/l

REL1

pH/mV

Sal

REL2

RCL

Sal

Time

Day.Month

Year

LoBat

Baud

No.

Ident

0 9 0 4

Tref25

Tref20

nLF

Lin

5t2

Auto

Store

Cal

Oxi

TEC

ARng

4 Set the date of the current day with <▲> <▼>.

5 Confirm with <RUN/ENTER>.

The date (month) flashes in the display.

6 Set the current month with <▲> <▼>.

7 Confirm with <RUN/ENTER>.

The year appears on the display.

8 Set the current year with <▲> <▼>.

9 Confirm with <RUN/ENTER>.

The hours flash on the display.

10 Set the current time with <▲> <▼>.

11 Confirm with <RUN/ENTER>.

The minutes flash on the display.

12 Set the current time with <▲> <▼>.

13 Confirm with <RUN/ENTER>.

The instrument switches to the measuring mode.

Commissioning Multi 1970i

3.4 Sensor quiver

To store the sensors during field operation and to keep the sensor element 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.

Warning

Do not store pH electrodes in the quiver for more than 10 hours. To store them for a longer period of time, use the watering cap filled with potassium chloride (3 mol/l) of the electrode.

Multi 1970i Operation

4 Operation

4.1 Operating structure

Active and inactive REL

socket

In addition to the pH/ORP sensor, the sensor on the REL1 or REL2 socket can be actuated (switched "active"). The other socket is not actuated ("inactive"). This switching over inside the instrument is made with the aid of a relay. The active REL socket is shown on the display.

The measured variable on the display can be selected as follows using the <M> key:

z Press <M> shortly

z Press <M> for a longer

period of time:

Several measuring modes are available within a measured variable. Switch over between the measured variables with the <▲> or <▼> key.

The options are summarized in the following diagram:

: Switch between the pH/ORP sensor and

the sensor at the active REL socket

Change the active Rel socket

Operation Multi 1970i

Note

When a sensor is connected to the active REL socket, the measuring instrument recognizes the sensor or the measuring cell and automatically switches to the measuring mode that was last active. As soon as the sensor is disconnected from the active REL socket, the instrument switches to the pH (mV) measuring mode again.

4.2 Switching on the measuring instrument

1 Press the <ON/OFF> key.

The display test appears briefly on the display. After this, the measuring instrument automatically switches to the measuring mode.

Measuring mode when

switching on

Sensors on the socket Measuring mode

pH REL

(active)

REL

(inactive)

pH or ORP measurement - depending on the last selected setting

:::

Note

The measuring instrument has an energy saving feature to avoid unnecessary battery depletion. The energy saving feature switches the measuring instrument off if no key has been pressed for an hour.

Last selected measuring mode. Only the last active REL socket is taken into account

The energy saving feature is not active

z if the power is supplied by the plug-in power supply,

z if the AutoStore function is active,

z if the communication cable and a PC with a running communication

program are connected,

z if the printer cable is connected (for external printers).

Multi 1970i Operation

4.3 pH value / ORP voltage

4.3.1 General information

Preparatory activities Perform the following preparatory activities when you want to measure:

1 Connect the pH depth armature or the pH electrode to the mea-

suring instrument. If necessary, press the <M> key repeatedly until the pH (pH measurement) or U (measurement of the ORP voltage) display appears.

2 Adjust the temperature of the buffer solutions or test solutions,

or measure the current temperature, if you measure without a temperature sensor.

3 Calibrate or check the measuring instrument with the elec-

trode.

4 Using <▲ > <▼>, toggle between the pH or mV measuring

modes.

Note

Incorrect calibration of pH electrodes leads to incorrect measured values. Calibrate regularly before measuring. You can only connect electrodes of the NTC30 type or without temperature sensor.

Warning

When connecting an earthed PC/printer, measurements cannot be performed in earthed media as incorrect values would result. The RS232 interface is not galvanically isolated.

Operation Multi 1970i

Temperature measure-

ment in pH measure-

ments

You can perform pH measurements with or without a temperature sensor as well as with the temperature sensor of an oxygen sensor or a conductivity measuring cell. The measuring instrument recognizes which sensors are connected and switches automatically to the correct mode for the temperature measurement.

The following cases are distinguishable.

Temperature sensor Display Mode

pH Cond or

Oxi

yes - TP Automatic with

pH temperature sensor

yes yes TP

- - Manual

-yesTP flashes

The temperature value of the second sensor (Cond or Oxi) in the same sample is taken over for the pH measurement*

* If you do not wish that, you can:

– either disconnect the 2nd sensor and use the manual temperature

input or

– use an electrode with a temperature sensor.

If a temperature sensor is connected, it is indicated on the display by TP.

Note

When calibrating without a temperature sensor (no TP display indicator displayed), enter the current temperature of the respective buffer solution manually using the <▲> <▼> keys while keeping the <RUN/EN-

TER> key depressed.

Multi 1970i Operation

4.3.2 Measuring the pH value

1 Perform the preparatory activities according to section 4.3.1.

2 Immerse the pH electrode in the test sample.

3 Press the <▲> <▼> keys repeatedly until pH appears on the

status display. The pH value appears on the display.

AutoRead AR

(Drift control) and hold

function

mg/l

REL1

pH/mV

Sal

REL2

RCL

Sal

Time

Day.Month

Year

LoBat nLF

4 When measuring without a connected temperature sensor:

The AutoRead function (drift control) checks the stability of the measurement signal. The stability has a considerable impact on the reproducibility of the measured values. With the aid of the hold function the measured value display is frozen.

Baud

No.

Ident

Tref25 Tref20

Options:

z Determine the current temperature using a thermometer

z TP display indicator not displayed, socket for the second

2 4 8

Auto

Store

Lin

Oxi

Cal

TEC

ARng

and, while keeping the <RUN/ENTER> key depressed, enter this temperature value with <▲> <▼>.

sensor is free: Connect the second sensor (Oxi or Cond) and immerse it in the same sample. TP flashes, the temperature is automatically measured using the second sensor.

With identical measurement conditions, the following criterion is valid for the AutoRead function:

Reproducibility Response time

Better than 0.02 > 30 seconds

For D. O. measurements, use the AutoRead function and hold function like this:

1 Call up the pH measuring mode with <▲> <▼>.

Operation Multi 1970i

2 Activate the AutoRead function with <AUTO READ>.

The current measured value is frozen (hold function).

3 Start AutoRead with <RUN/ENTER>.

AR flashes until a stable measured value is reached. This measured value is transmitted to the interface.

4 If necessary, start the next AutoRead measurement with

<RUN/ENTER>.

5 To terminate the AutoRead function: Press the

<AUTO READ> key.

Note

The current AutoRead measurement can be terminated at any time (accepting the current value) by pressing <RUN/ENTER>.

4.3.3 Measuring the ORP voltage

In conjunction with an ORP electrode, e.g. SenTix ORP, the measuring instrument can measure the ORP voltage (U) of a solution.

1 Perform the preparatory activities according to section 4.3.1.

2 Submerse the ORP electrode in the sample.

3 Press the <▲> <▼> key until the U status display appears. The

ORP voltage (mV) of the test sample appears on the display.

4 Wait for a stable measured value.

pH/

Store

TEC

ARng

mg/l

REL1

REL2

Sal

RCL

Sal

Time

Day.Month

Year

LoBat nLF

Note

ORP electrodes are not calibrated. However, you can check ORP electrodes using a test solution.

Baud

Ident

Tref25

No.

Tref20

Lin

Oxi

2 4 8

Auto

Cal

Multi 1970i Operation

4.3.4 pH calibration

Why calibrate? pH electrodes age. This changes the asymmetry (zero point) and slope

of the pH electrode. As a result, an inexact measured value is displayed. Calibration determines the current values of the asymmetry and slope of the electrode and stores them in the measuring instrument. Thus, you should calibrate at regular intervals.

When to calibrate? z After connecting another electrode

z When the sensor symbol flashes, i.e. after the calibration interval

has expired

Calibration points Calibration can be made with one or two buffer solutions (single-point

or two-point calibration). The measuring instrument determines the following values and calculates the calibration lines as follows:

Determined values Values of the calibration lines

1-point ASY z Asymmetry = ASY

z Slope = Nernst slope (59.16 mV/

pH at 25 °C)

2-point ASY

SLO

z Asymmetry = ASY

z Slope = SLO

AutoCal TEC is specially matched to the WTW technical buffer solutions as a fully au-

tomatic two-point calibration. The buffer solutions are automatically recognized by the measuring instrument. Depending on the instrument setting (see section 4.9 C

ONFIGURATION), the instrument displays the

relevant buffer nominal value or the current electrode voltage in mV. The calibration can be terminated after the first buffer solution. This corresponds to a single-point calibration. To do this, the instrument uses the Nernst slope (-59.2 mV/pH at 25 °C) and determines the asymmetry of the electrode.

AutoRead The calibration procedure automatically activates the AutoRead func-

tion. The current AutoRead measurement can be terminated at any time (accepting the current value) by pressing <RUN/ENTER>.

Displaying the calibra-

tion data

Printing the

calibration protocol

You can view the data of the last calibration on the display. The proceeding is described on page 50.

The calibration protocol contains the calibration data of the current calibration. You can transmit the calibration protocol to a printer via the serial interface (see O

INTERFACE, page 53).

UTPUTTING THE CALIBRATION PROTOCOL ON THE

Operation Multi 1970i

Note

You can automatically print a calibration protocol after the calibration. To do so, connect a printer to the interface according to section 4.8.2 before calibrating. After a valid calibration, the record is printed.

Sample printout:

CALIBRATION PROTOCOL

02.03.02 14:19 Device No.: 12345678 Calibration pH Cal time: 01.03.01 / 15:20 Cal interval: 7d AutoCal TEC Tauto Buffer 1 2.00 Buffer 2 4.01 Buffer 3 7.00 * Buffer 4 10.01 C1 184.1 mV 25.0°C C2 3.0 mV 25.0°C S1 -59.4 mV/pH ASY1 - 4 mV Probe: +++

Multi 1970i Operation

Calibration evaluation After calibrating, the measuring instrument automatically evaluates the

calibration. The asymmetry and slope are evaluated separately. The worst evaluation appears on the display.

Display Asymmetry

[mV]

-15 ... +15 -60.5 ... -58

-20 ... +20 -58 ... -57

-25 ... +25 -61 ... -60.5

-30 ... +30 -62 ... -61

Clean the electrode according to the electrode operating manual

Slope [mV/pH]

-57 ... -56

-56 ... -50

Preparatory activities

Perform error elimination according to chapter 6 W

DO IF...

HAT TO

< -30 or > 30

< -62 or > -50

1 Connect the pH electrode to the measuring instrument.

If necessary, press the <M> key repeatedly until the status display pH (pH measurement) or U (measurement of the ORP voltage) appears.

2 Keep the buffer solutions ready.

3 Adjust the temperature of the solution and measure the current

temperature if the measurement is made without the use of a temperature sensor (the TP display indicator is missing from the display).

Operation Multi 1970i

AutoCal TEC For this procedure, use any two WTW technical buffer solutions (pH

values at 25 °C: 2.00 / 4.01 / 7.00 / 10.01).

Note

The calibration for pH 10.01 is optimized for the WTW technical buffer solution TEP 10 Trace or TPL 10 Trace. Other buffer solutions can lead to an erroneous calibration. The correct buffer solutions are given in the WTW catalog or in the Internet.

Note

The buffer solutions are automatically recognized by the measuring instrument. Depending on the instrument setting (see section 4.9 C er nominal value or the current electrode voltage in mV.

Note

Skip the steps 2 and 7 if you use a pH electrode with temperature sensor or the temperature sensor of a conductivity measuring cell or a D. O. sensor.

ONFIGURATION), the instrument displays the relevant buff-

Starting the calibration

1 Press the <CAL> key. The Ct1 display and the function display

AutoCal TEC appears. The sensor symbol displays the evalu-

ation of the last calibration (or no sensor symbol in the delivery state or after the measurement parameters have been reset).

mg/l

REL1

pH/mV

Sal

REL2

RCL

Sal

Time

Day.Month

Year

LoBat nLF

2 If required, enter the temperature of the first buffer solution with

3 Immerse the pH electrode in the first buffer solution.

4 Press the <RUN/ENTER> key.

Lin

Oxi

2 4 8

Store

Auto

TEC

ARng

Cal

Baud

No.

Ident

Tref25 Tref20

<▲> <▼> while keeping the <RUN/ENTER> key depressed.

The AR display indicator flashes. The electrode voltage (mV) or the buffer nominal value appears on the display. Example:

Multi 1970i Operation

mVS/

mg/l

REL1

REL2

Sal

RCL

TEC

ARng

mg/l

REL1

Sal

Time

Day.Month

Year

LoBat nLF

5 When the measured value is stable, Ct2 appears.

Baud

No.

Ident

Tref25 Tref20

Lin

2 4 8

Auto

Oxi

Cal

Sal

REL2

RCL

Sal

Time

Day.Month

Year

LoBat nLF

700

Baud

No.

Ident

Lin

Oxi

2 4 8

Auto

Cal

Tref25 Tref20

TEC

ARng

mg/l

REL1

pH/mV

Sal

REL2

RCL

Sal

Time

Day.Month

Year

LoBat nLF

Note

At this point, the AutoCal TEC calibration can be terminated with <M>. This corresponds to a single-point calibration. To do this, the instru- ment uses the Nernst slope (-59.2 mV/pH at 25 °C) and determines the asymmetry of the electrode.

6 Thoroughly rinse the electrode with distilled water.

7 If required, enter the temperature of the second buffer solution

8 Immerse the pH electrode into the second buffer solution.

9 Press the <RUN/ENTER> key.

Lin

Oxi

2 4 8

Store

Auto

TEC

ARng

Cal

Baud

No.

Ident

Tref25 Tref20

with <▲> <▼> while keeping the <RUN/ENTER> key depressed.

The AR display indicator flashes. The electrode voltage (mV) or the buffer nominal value appears on the display. Example:

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