Xylem CG 842 User Manual

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Gebrauchsanleitung / Operating manual

Labor-pH-Meter

Laboratory pH Meter

CG 842

ba12242de_2 09/99

Bedienungsanleitung Seite 1 Operating manual Page 45

Laboratory pH Meter

CG 842

Operating Manual

ba12242e_2 09/99

Accuracy when

going to press

All details contained in this operating manual are valid data at the time of going to press. However, SCHOTT may add details for both technical and commercial reasons, or in order to fulfil legal requirements of different countries. This does not affect the characteristics described.

Warranty

declaration

The designated instrument is covered by a warranty of three years from the date of purchase. The instrument warranty extends to manufacturing faults that are determined within the period of warranty. The warranty excludes components that are replaced during maintenance such as batteries, etc.

The warranty claim extends to restoring the instrument to readiness for use but not, however, to any further claim for damages. Improper handling or unauthorized opening of the instrument invalidates any warranty claim.

To ascertain the warranty liability, return the instrument and proof of purchase together with the date of purchase freight paid or prepaid.

Reprinting - even as excerpts - is only allowed with the explicit written authorization of SCHOTT Geräte GmbH, Hofheim. Printed in Germany.

List of contents

1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

1.1 Keyboard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .50

1.2 Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

1.3 Sockets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

1.4 Declaration of conformity . . . . . . . . . . . . . . . . . . . . .52

1.5 Technical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . .53

2 Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

2.1 Authorized use . . . . . . . . . . . . . . . . . . . . . . . . . . . .58

2.2 General safety instructions . . . . . . . . . . . . . . . . . . .58

3 Commissioning . . . . . . . . . . . . . . . . . . . . . . . . 61

4 Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

4.1 Switch on the instrument . . . . . . . . . . . . . . . . . . . . .63

4.2 Measuring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

4.2.1 Measuring the pH value . . . . . . . . . . . . . . . .6 5

4.2.2 Measuring the Redox voltage . . . . . . . . . . .66

4.3 Calibrating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .67

4.3.1 AutoCal TEC . . . . . . . . . . . . . . . . . . . . . . . . 69

4.3.2 AutoCal DIN . . . . . . . . . . . . . . . . . . . . . . . . .71

4.3.3 ConCal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

4.4 Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .76

5 Maintenance, cleaning, disposal . . . . . . . . . . 77

5.1 Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .77

5.2 Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .78

5.3 Disposal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

6 What to do if... . . . . . . . . . . . . . . . . . . . . . . . . . 79

7 Lists . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

List of contents

1Overview

Overview

The compact pH measurements rapidly and reliably. The

CG 842

fort, reliability and measuring safety for all applications. The proven calibration procedures and special

function support your work with the pH meter.

CG 842

provides the highest degree of operating com-

precision pH meter lets you perform

AutoRead

1 Keypad 2 Display

3 Sockets

Note

The measuring instrument can also be delivered as part of a set. Information on this and other accessories is available in the SCHOTT general catalog.

Overview

1.1 Keyboard

Switch measuring instrument ON/OFF

Select measuring mode

<pH>

Call up calibration procedure

<CAL>

Activate/deactivate AutoRead

Reduce values, scroll

Confirm inputs, start AutoRead

Increase values, scroll

1.2 Display

1.3 Sockets

Overview

Status line

Measured value display

Function and temperature displ a y

1 2 3 4

1 Socket according to DIN 19262/BNC 2 Pt1000/NTC30 connector

for pH combined electrodes with

temperature probe

3 Reference electrode connector 4 Connector for

plug-in power supply (optional)

Caution

Only connect probes to the instrument that cannot feed excessive voltages or currents (> SELV and > circuit with current limiter). Almost all commercial electrodes - especially SCHOTT electrodes - meet these requirements.

Overview

1.4 Declaration of conformity

29.03.99

SCHOTT Geräte GmbH

Im Langgewann 5

D 65719 Hofheim am Taunus

Deutschland, Germany, Allemagne

29. März, March 29rd, 29, Mars, 1999

AGQSF0000-A056-00/990329

Ambient

temperature

Overview

1.5 Technical data

Storage temperature - 25 °C ... + 65 °C Operating temperature 0 °C ... + 55 °C

Measuring ranges

and resolution

Measuring accuracy

(± 1 digit)

Allowable relative humidity

Annual mean: < 75 % 30 days/year: 95 % Other days: 85 %

pH (resolution selectable)

- 2.000 ... + 16.000

- 2.00 ... + 16.00

U [mV] - 999.9 ... + 999.9

- 1999 ... + 1999 T [°C] - 5.0 ... + 100.0 T [°F] + 23.0 ... + 212.0

Given as measuring uncertainty at a confidence level of 95%. All accuracies additionally depend on the accuracies of the measuring probes.

pH (± 2 pH units around the

± 0.005 at + 15 °C ... + 35 °C ± 0.01

calibration point) U [mV] ± 0.4 at + 15 °C ... + 35 °C

± 1

T [°C] NTC 30: ± 0.1

PT 1000: ± 0.5 at 0 °C ... 15 °C ± 0.1 at 15 °C ... 35 °C ± 1 at 35 °C ... 55 °C

T [°F] NTC 30: ± 0.2

PT 1000: ± 0.9 at 32 °F ... 59 °F ± 0.2 at 59 °F ... 95 °F ± 1.8 at 95 °F ... 131 °F

Overview

Housing

EMC and

VDE norms

Length [mm] 230 Width [mm] 210 Height [mm] 70 Weight [kg] Approx. 0.850 Material ABS

Interference emission (generic standard)

EN 50081-1 FCC class A

Test marks

Display

Temperature com-

pensation

Keypad Foil keypad (Polyester)

Interference immunity

EN 50082-1

(generic standard) Protective class 3, EN61010-1 Climatic class 2, VDI/VDE 3540

TÜV GS, UL/CUL, CE

Multifunctional LCD

Automatically with Pt 1000/NTC (30 k

-5 ... 99.9 °C

Manual input -20 ... 130 °C resolution 1K

Overview

Energy supply

Batteries 4 x 1.5 V AA type alkaline manga-

nese batteries Runtime Approx. 3000 operating hours Mains power supply

(option)

Connection max. overvoltage cate-

gory II (valid for all plug-in power

supply units):

Plug-in power supply (Euro plug):

Type no.: Z851

Order no.: 28 520 4897

FRIWO FW3288, 11.8134

Friwo Part No. 1816492

Input: 230V ~ / 50 Hz / 23 VA

Output: 6 V = / 1,8 A /10,8 VA

Plug-in power supply (US plug):

Type no.: Z852

Order no.: 28 520 4901

FRIWO FW3288, 11.8451

Friwo Part No. 1816493

Input: 120V ~ / 60 Hz / 21,5 VA

Output: 6 V = / 1,8 A

Plug-in power supply (UK plug):

Type no.: Z849

Order no.: 28 520 4975

FRIWO FW3288, 11.8453

Friwo Part No. 1770896

Input: 230V ~ / 50 Hz / 23 VA

Output: 6 V = / 1,8 A

Overview

Connections

Input amplifier

Calibration modes

Electrodes Socket according to DIN 19 262

or BNC

4 mm socket for reference elec-

trode

Temperature probe 4 mm socket for

temperature probe

Plug-in power supply

2-pole special Friwo

unit

-12

Ω

Input impedance ≥ 10 Offset current ≤

AutoCal TEC With Technical buffers

(given in pH):

2.00; 4.00; 7.00; 10.00 at 25 °C;

buffers are temperature com-

pensated in the range 0 ... 90 °C

AutoCal DIN With standard buffers according

to DIN 19 266/NIST (given in

pH):

1.68; 4.01; 6.87; 9.18 at 25 °C;

buffers are temperature com-

pensated in the range 0 ... 90 °C

ConCal With any buffers;

single-point and two-point cali-

bration,

manual acceptance of measured

values and temperature input

Safety

2 Safety

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

Target group This measuring instrument was developed for use in the lab-

oratory. 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.

Symbols used

Caution

indicates instructions that have to be followed to prevent damage to your instrument.

Warning

indicates instructions that have to be followed to protect yourself and the instrument from dangerous electrical voltage.

Note

Indicates notes that draw your attention to special features.

Note

Indicates cross-references to other documents, e.g. application reports, operating manuals of combination electrodes, etc.

Safety

2.1 Authorized use

This instrument is authorized exclusively for pH and Redox measurements in the laboratory. The technical specifications as given in the chapter, T

CAL DATA, must be observed. Only the operation and run-

ECHNI-

ning of the measuring instrument according to the instructions given in this operating manual is authorized. Any other use is considered unauthorized.

2.2 General safety instructions

This instrument is constructed and tested in compliance with the EN 61010-1 safety regulations for electronic measuring instruments. It left the factory in a safe and secure technical condition.

Function and opera-

tional safety

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

The smooth functioning and operational safety of the instrument can only be guaranteed under the climatic conditions specified in the chapter 1.5 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.

Caution

The instrument is only allowed to be opened by personnel authorized by SCHOTT.

Safety

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:

l the instrument has been damaged in transport l the instrument has been stored under adverse conditions

for a lengthy period of time

l the instrument is visibly damaged l the instrument no longer operates as described in this

manual

If you are in doubt contact the supplier of the instrument.

Obligations of the

operator

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

l EEC directives for protective labor legislation l National protective labor legislation l Safety regulations l Safety datasheets of the chemical manufacturer.

Safety

Commissioning

3 Commissioning

Perform the following activities for the initial commissioning:

l Set the °C or °F l Set the resolution l Connect the plug-in power supply (optional).

Setting °C or °F The temperature can be displayed in °C or in °F . In the de-

livery condition, the measuring instrument is preset to °C. To change the unit proceed as follows:

1 Switch the measuring instrument off. 2 Press and hold down the <pH> key.

Setting the

resolution

3 Press the <on/off> key.

4 Toggle between °C and °F by pressing <▲> <▼>. 5 Confirm with <run/enter>.

The measuring instrument switches to the measuring mode.

1 Press and hold down the <run/enter> key. 2 Press the <pH> key. The measured values are dis-

played with a high resolution, e. g. pH = 4.012.

Commissioning

3 Press the <run/enter> and <pH> keys again.

The measured values are displayed with a low resolution, e. g. pH = 4.01.

Connecting the

plug-in power

supply (optional)

The measuring instrument works battery-powered. It can, however, also be supplied by the plug-in power supply which is available as an accessory.

Warning

The line voltage on site must lie within the input voltage range of the original plug-in power supply unit (see section

ECHNICAL DATA).

1.5 T

Caution

Use original plug-in power supplies only (see section 1.5 T

ECHNICAL DATA).

1 Insert the plug (1) into the socket (2) of the pH meter. 2 Connect the original plug-in power supply (3) to an

easily accessible mains socket.

Operation

4Operation

4.1 Switch on the instrument

1 Place the instrument on a flat surface and protect it

against intense light and heat.

2 Press the <on/off> key.

display test

The The instrument then switches automatically to the previously selected measuring mode.

3 Connect the pH electrode to the instrument.

The measuring instrument is ready for operation.

appears briefly on the display.

Note

The instrument has an energy saving feature to avoid unnecessary battery depletion. The energy saving feature switches the instrument off if no key has been pressed for an hour. The energy saving feature is not active if the instrument is supplied by the plug-in power supply.

Operation

4.2 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 measurement is made without a temperature probe.

3 Calibrate or check the instrument with the pH elec-

trode according to section 4.3.

4 Select the measuring mode by pressing <pH>.

Note

Incorrect calibration of the pH electrode will result in incorrect measured values. Therefore, regularly perform calibration before measuring.

Temperature probe Measurements can be performed with and without a temper-

ature probe. A connected temperature probe is indicated by TP on the display.

Note

The pH meter automatically recognizes the type of the temperature probe used. As a result, you can connect electrodes with the NTC30 or Pt1000.

The temperature measurement is absolutely essential for a reproducible pH measurement. If the measurement is made without a temperature probe, proceed as follows:

1 Determine the current temperature using a thermo-

meter.

2 Set up the temperature by pressing <

▲> <▼>.

Note

When calibrating without a temperature probe, set up the current temperature of the respective buffer solution manually by pressing the <

▲> <▼> keys.

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.

AutoRead AR (Drift control)

3 Press the <pH> key until

appears in the status

display. The pH value appears on the display.

The

AutoRead

function (drift control) checks the stability of the measurement signal. The stability has a considerable effect on the reproducibility of the measured values.

For identical measurement conditions, the following criteria apply:

l pH value: better than 0.02 (setting time: > 30 s)

1 Call up the pH measuring mode by pressing <pH>. 2 Activate the AutoRead function by pressing <auto

read>. The current measured value is frozen (Hold function).

3 Start the AutoRead function by pressing

<run/enter>. AR flashes on the display until a stable measured value is reached.

4 If necessary, start the next AutoRead measurement

by pressing <run/enter>.

5 To terminate the AutoRead function: Press the <auto

read> key.

Operation

Note

The current AutoRead measurement (with acceptance of the current value) can be terminated at any time by pressing

<run/enter>.

4.2.2 Measuring the Redox voltage

The pH meter can measure the Redox voltage (mV) of a solution when connected with a Redox electrode, e.g. BlueLine 31 Rx.

1 Perform the preparatory activities according to sec-

tion 4.2. 2 Immerse the Redox electrode into the test sample. 3 Press the <pH> key repeatedly until U appears in the

status line.

The Redox voltage (mV) of the sample appears on

the display. 4 Wait for a stable measured value.

Note

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

Operation

4.3 Calibrating

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 they are stored in the instrument. Thus, you should calibrate at regular intervals.

Note

Always calibrate after connecting another electrode.

You can choose between 3 calibration procedures:

AutoCal TEC is specially adapted to the Technical Buffer Solutions as a

fully automatic two-point calibration. The buffer solutions are automatically recognized by the instrument. The following values are available:

2.00; 4.00; 7.00; 10.00.

AutoCal DIN is specially adapted to permanently programmed buffer so-

lutions according to DIN 19266 as a fully automatic twopoint calibration. The buffer solutions are automatically recognized by the instrument. The following values are available:

1.68; 4.01; 6.87; 9.18.

ConCal is the conventional two-point calibration with 2 freely

selectable buffer solutions or single-point calibration as the rapid method.

AutoRead In calibration using AutoCal TEC and AutoCal DIN, the

toRead

function is automatically activated.

Au-

The current AutoRead measurement (with acceptance of the current value) can be terminated at any time by pressing

<run/enter>.

Operation

Calibration

evaluation

After the calibration, the instrument automatically evaluates the current status. The asymmetry and slope are separately evaluated. The worst evaluation appears on the display.

Display Asymmetry

[mV]

Slope

[mV/pH]

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

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

-25 ... +25 56 ... 57 or

60.5 ... 61

-30 ... +30 56 ... 50 or 61 ... 62

Preparatory

activities

Clean the electrode according to the electrode operating manual



Clear the fault according to chapter 6 W

HAT TO DO IF...

< -30 or > 30

< 50 or > 62

1 Switch on the instrument by pressing <on/off>. 2 Connect the pH electrode to the instrument. 3 Keep the buffer solutions ready. 4 Adjust the temperature of the solutions and measure

the current temperature if the measurement is performed without a temperature probe.

Operation

4.3.1 AutoCal TEC

Use any two of the Technical Buffer Solutions for this procedure.

Note

Steps 2 and 6 are not required if you use a temperature probe.

1 Press the <CAL> key repeatedly until Ct1 and the

AutoCal TEC function display appear.

2 If necessary, set the temperature of the buffer solu-

tion by pressing <

▲> <▼> .

3 Submerse the pH electrode in the first buffer solution. 4 Press the <run/enter> key.

AR flashes on the display. The electrode voltage (mV) appears on the display. As soon as a stable value is recognized, Ct2 appears.

5 Thoroughly rinse the electrode with distilled water.

Operation

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 <run/enter> key.

AR flashes on the display. The electrode voltage (mV) appears on the display. As soon as a stable value is recognized, AR disappears. The sensor symbol shows the electrode evaluation after the two-point calibration. The value of the slope (mV/pH) appears on the display.

9 Press the <run/enter> key.

The value of the asymmetry (mV) appears on the display.

10 To return to the measuring mode: Press the <pH>

key.

Operation

4.3.2 AutoCal DIN

Use two different DIN buffer solutions for this procedure:

DIN buffer solution pH

A 1.68 C 4.01 D 6.87

F 9.18

Note

Steps 2 and 6 are not required if you use a temperature probe.

1 Press the <CAL> key repeatedly until Cd1 and the

AutoCal DIN function display appear.

2 If necessary, set the temperature of the buffer solu-

tion by pressing <

▲> <▼>.

3 Submerse the pH electrode in the first buffer solution. 4 Press the <run/enter> key.

AR flashes on the display. The electrode voltage (mV) appears on the display. As soon as a stable value is recognized, Cd2 appears.

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 <run/enter> key.

9 Press the <run/enter> key.

The value of the asymmetry (mV) appears on the display.

10 To return to the measuring mode: Press the <pH>

key.

4.3.3 ConCal

Operation

Two-point

calibration

Use two buffer solutions for this procedure:

l pH 7.0 ± 0.5 l any other buffer solution

Note

Steps 2 and 9 are not required if you use a temperature probe.

1 Press the <CAL> key repeatedly until ASY and the

ConCal function display appear.

2 If necessary, set the temperature of the buffer solu-

tion by pressing <

▲> <▼>.

3 Submerse the pH electrode in the pH 7.0 ± 0.5 buffer

solution.

4 Press the <run/enter> key.

The measured pH value appears on the display.

5 Set the nominal pH value of the buffer solution (at the

current temperature) by pressing the <

▲> <▼> keys.

6 Press the <run/enter> key.

The value of the asymmetry (mV) and the sensor symbol appear on the display.

7 Press the <run/enter> key.

SLO(pe) appears on the display.

Operation

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 <run/enter> key.

The second measured pH value appears on the display.

12 Set the nominal pH value of the second buffer solu-

tion (at the current temperature).

13 Press the <run/enter> key.

The value of the slope (mV/pH) appears on the display. The sensor symbol shows the evaluation of the electrode after the two-point calibration.

14 Press the <run/enter> key.

The value of the asymmetry (mV) appears on the display again.

15 To return to the measuring mode: Press the <pH>

key.

Operation

Single-point

calibration

Use a buffer solution in the range pH = 7.0 ± 0.5 for this procedure.

Note

Only the electrode asymmetry is determined in single-point calibration. The slope of the last two-point calibration is retained.

Note

Step 2 is not required if you use a temperature probe. The TP display indicates an active temperature measurement.

1 Press the <CAL> key repeatedly until ASY and the

ConCal function display appear.

2 Set the temperature of the buffer solution by pressing

▲> <▼>.

3 Submerse the pH electrode in the buffer solution. 4 Press the <run/enter> key.

The measured pH value appears on the display.

5 Set the nominal pH value of the buffer solution (at the

current temperature) by pressing the <

▲> <▼> keys.

6 Press the <run/enter> key.

The value of the asymmetry (mV) and the sensor symbol for the evaluation of the electrode appears on the display.

7 To return to the measuring mode: Press the <pH>

key.

Operation

Basic settings The following functions are reset (initialized) to the values

4.4 Reset

they had on delivery: Measuring mode pH

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 <run/enter> key. 2 Press the <CAL> key.

3 Toggle between no and yes by pressing <▲> <▼>.

yes: reset parameters. no: retain settings.

4 Confirm with <run/enter>.

The pH meter changes automatically to the pH measuring mode.

Maintenance, cleaning, disposal

5 Maintenance, cleaning, disposal

5.1 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.

3 Insert four new batteries (Type Mignon AA) into the

battery compartment.

4 Close the battery compartment (1).

Caution

Make sure that the poles of the batteries are the right way round. The

± signs in the battery compartment must correspond to

± signs on the batteries.

the Only use leakproof alkaline manganese batteries.

Note

See the relevant operating manual of the electrode for instructions on maintenance.

Maintenance, cleaning, disposal

5.2 Cleaning

Occasionally wipe the outside of the measuring instrument with a damp, lint-free cloth. Disinfect the housing with isopropanol as required.

Caution

The housing is made of synthetic material (ABS). Thus, avoid contact with acetone or similar detergents that contain solvents. Remove any splashes immediately.

5.3 Disposal

Packing The measuring instrument is sent out in a protective trans-

port packing. We recommend: Keep the packing material. The original packing protects the instrument against damage during transport.

Batteries This note refers to the battery regulation that applies in the

Federal Republic of Germany. We would ask end-consumers in other countries to follow their local statutory provisions.

Note

In compliance with §14 of the B

ATTERY REGULATION, we

would like to point out that this instrument contains batteries. Batteries that have been removed must only be disposed of at the recycling facility set up for this purpose or via the retail outlet. It is illegal to dispose of them in household refuse.

Measuring

instrument

Dispose of the measuring instrument as electronic waste at an appropriate collection point. It is illegal to dispose of them in household refuse.

6 What to do if...

What to do if...

Error message,

I/

Error message,



Cause Remedy

pH electrode:

– Not connected – Connect electrode – Air bubbles in front of the

diaphragm

– Air in the diaphragm – Extract air or moisten

– Cable broken – Replace electrode – Gel electrolyte dried out – Replace electrode

Cause Remedy

pH electrode: – Diaphragm contaminated – Clean diaphragm

– Remove air bubbles

diaphragm

– Membrane contaminated – Clean membrane – Moisture in the plug – Dry plug – Electrolyte obsolete – Replenish electrolyte or

replace electrode – Electrode obsolete – Replace electrode – Electrode broken – Replace electrode

Measuring instrument: – Incorrect calibration

procedure

– Incorrect solution

temperature (without temperature probe)

– Socket damp – Dry socket

– Select correct

procedure

– Set up correct

temperature

What to do if...

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

measured value

Cause Remedy

pH electrode: – Diaphragm contaminated – Clean diaphragm – Membrane contaminated – Clean membrane

Sample: – pH value not stable – Measure with air

excluded if necessary

– Temperature not stable – Adjust temperature if

necessary

Electrode + sample: – Conductivity too low – Use suitable electrode – Temperature too high – Use suitable electrode

LoBat

– Organic liquids – Use suitable electrode

Cause Remedy

– Batteries almost depleted – Replace batteries (see

section 5.1 M

AINTENANCE)

What to do if...

Obviously incorrect

measured values

Instrument does not

react to keystroke

Cause Remedy

– pH electrode unsuitable – Use suitable electrode – Temperature difference

between buffer and

– Adjust temperature of

buffers or samples

sample too large

– Measuring procedure not

– Follow special procedure

suitable

Cause Remedy

– Operating state

undefined or EMC electric stress unallowed

– Processor reset:

Press the <auto read> key and switch on the instrument

What to do if...

Lists

7Lists

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. However, terms that should already be familiar to the target group are not described here.

Index The index helps you find the topics that you are looking for.

Lists

Abbreviations

AR AutoRead (drift control) ARng Automatic range switching

Measuring instrument measures with high-

est resolution ASY Asymmetry AutoCal DIN Automatic calibration with DIN buffer solu-

tions AutoCal TEC Automatic calibration with Technical Buffer

Solutions Cal Calibration Cd... Calibration with DIN buffer solutions

(acc. to DIN 19266) ConCal Conventional one / tw o po in t ca l ibration Ct... Calibration with Technical Buffer Solutions E3 Error message (see W

HAT TO DO IF ...)

InI Initialization

Resets individual basic functions to

the status they had on delivery LoBat Low Battery

Batteries are almost empty mV Voltage unit mV/pH Unit of the electrode slope OFL Overflow

Display range exceeded pH pH value

S Slope SELV Safety Extra Low Voltage SLO Slope

Slope setting on calibration

TP Temperature probe

Temperature measurement active

ASY Asymmetry potential

°C Temperature unit, °Celsius °F Temperature unit, Fahrenheit

Lists

Glossary

Asymmetry Zero point of a pH electrode.

Resolution Number of decimal places that appear for a measured val-

ue.

AutoRead Monitors the electrode drift and releases the measured val-

ue only after the stability criterion has been reached. In this way, this procedure ensures the highest degree of precision and reproducibility.

Diaphragm Contact point between the reference electrolytic solution

and the sample.

Drift control See A

UTOREAD.

Test solution Stable solution with a precisely known Redox voltage.

Buffer solution Stable solution with a precisely known pH value.

Redox voltage Potentiometric quantity.

Slope Specifies the voltage change per pH unit.

Index

Lists

asymmetry 67 authorized use 58 AutoCal DIN 67, 71 AutoCal TEC 67, 69 AutoRead 65

basic settings 76 battery compartment 77 Buchsenfeld 51

calibrating 67 calibration evaluation 68 calibration procedures 67 ConCal 67, 73

delivery condition 76 display 51 drift control 65

energy saving feature 63 error messages 79

place of the instrument 63 plug-in power supply 62 power supply 54, 62

Redox electrode 66 Redox voltage 66 replacing the batteries 77 reset 76

safety 57 safety precautions 57 setting the resolution 61 setting the temperature unit 61 single-point calibration 67

ConCal 75

slope 67

temperature probe 64 two-point calibration 67

AutoCal DIN 72 AutoCal TEC 70 ConCal 73

initialize 76

keys 50

LoBat 80

operational safety 58

Xylem CG 842 User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

1Overview

1.1 Keyboard

1.2 Display

1.3 Sockets

1.4 Declaration of conformity

1.5 Technical data

2 Safety

2.1 Authorized use

2.2 General safety instructions

3 Commissioning

4Operation

4.1 Switch on the instrument

4.2 Measuring

4.2.1 Measuring the pH value

4.2.2 Measuring the Redox voltage

4.3 Calibrating

4.3.1 AutoCal TEC

4.3.2 AutoCal DIN

4.3.3 ConCal

4.4 Reset

5 Maintenance, cleaning, disposal

5.1 Maintenance

5.2 Cleaning

5.3 Disposal

6 What to do if...

7Lists