How it Works
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CG 843
User Manual
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Xylem CG 843 User Manual

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Laboratory pH Meter
CG 843
Operating Manual
ba12243e_2 09/99
69
Accuracy when
going to press
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.
70
Copyright
© Hofheim SCHOTT Geräte GmbH 1999
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 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
1.1 Keypad . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .74
1.2 Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .75
1.3 Sockets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .75
1.4 Declaration of conformity . . . . . . . . . . . . . . . . . .76
1.5 Technical data . . . . . . . . . . . . . . . . . . . . . . . . . .77
2 Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
2.1 Authorized use . . . . . . . . . . . . . . . . . . . . . . . . .82
2.2 General safety instructions . . . . . . . . . . . . . . . .82
3 Commissioning . . . . . . . . . . . . . . . . . . . . . . . . 85
4 Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
4.1 Switch on the instrument . . . . . . . . . . . . . . . . . .87
4.2 Measuring . . . . . . . . . . . . . . . . . . . . . . . . . . . . .88
4.2.1 Measuring the pH value . . . . . . . . . . . . .90
4.2.2 Measuring the Redox voltage . . . . . . . . .91
4.2.3 Transmitting measured values . . . . . . .92
4.3 Calibrating . . . . . . . . . . . . . . . . . . . . . . . . . . . . .93
4.3.1 Calibration interval (Int 3) . . . . . . . . . . . .96
4.3.2 AutoCal TEC . . . . . . . . . . . . . . . . . . . . .97
4.3.3 AutoCal DIN . . . . . . . . . . . . . . . . . . . . .100
4.3.4 ConCal . . . . . . . . . . . . . . . . . . . . . . . . .103
4.4 Storing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .106
4.4.1 Manual storage . . . . . . . . . . . . . . . . . . .106
4.4.2 Switching on AutoStore (Int 1) . . . . . . .108
4.4.3 Outputting the data storage . . . . . . . . .110
4.4.4 Clearing the storage . . . . . . . . . . . . . . .113
4.5 Data transmission . . . . . . . . . . . . . . . . . . . . . .114
4.5.1 Data transmission interval (Int 2) . . . . .114
4.5.2 Recorder (analog output) . . . . . . . . . . .116
4.5.3 PC/external printer (RS232 interface) .117
4.6 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . .118
4.7 Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .122
71
List of contents
5 Maintenance, cleaning, disposal . . . . . . . . . 125
5.1 Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . .125
5.2 Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . .126
5.3 Disposal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .126
6 What to do if... . . . . . . . . . . . . . . . . . . . . . . . . 127
7 Lists . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
72

1Overview

Overview
The compact pH measurements rapidly and reliably. The vides the highest degree of operating comfort, reliability and measuring safety for all applications.
The proven calibration procedures and special
AutoRead
CG 843
function support your work with the pH meter.
precision pH meter lets you perform
CG 843
3
2
1
pro-
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.
73
Overview

1.1 Keypad

Switch measuring instrument on or off
<on/off>
Select measuring mode
<pH>
Call up calibration procedure
<CAL>
Activate/deactivate AutoRead
<auto read>
Store measured value
<STO>
Display/transmit measured values
<RCL>
Reduce values, scroll
▼>
<
Confirm inputs, start AutoRead
<run/enter>
74
Increase values, scroll
▲>
<

1.2 Display

1.3 Sockets

Overview
Status line
Measured value display
Function and temperature displ a y
12345
1 Socket according to DIN 19262/BNC 2 PT 1000/NTC30 connection for pH combined electro-
de with temperature probe
3 Reference electrode connection 4 RS 232 interface/analog output 5 Connection 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).
Nearly all commercial electrodes – especially SCHOTT electrodes – meet these requirements.
75
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-A058-00/990329
76
Ambient
temperature
Overview

1.5 Technical data

Storage temperature - 25 °C ... + 65 °C Operating temp. 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 - 2.000 ... + 16.000
- 2.00 ... + 16.00
resolution selectable
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
± 0.005 at + 15 °C ... + 35 °C ± 0.01
the 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
77
Overview
Housing
EMC and
VDE norms
Length [mm] 230 Width [mm] 210 Height [mm] 70 Weight [kg] Approx. 1.3
(without plug-in power supply unit)
Material ABS
Interference emission (generic standard)
EN 50081-1 FCC class A
Interference immunity (generic standard)
Protective class 3, EN61010-1 Climatic class 2, VDI/VDE 3540
Test marks
Display
TÜV GS, UL/CUL, CE
Multifunctional LCD
Keypad Foil keypad (Polyester)
EN 50082-1
78
Power supply
Overview
Batteries 4 x 1.5 V AA type alkaline manganese
batteries Runtime Approx. 3000 operating hours Mains power
supply (option)
Plug-in power supply unit:
Connection max. overvoltage category II
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
Data storage Ring store for 200 value pairs, pH/mV, temperature
Temperature
compensation
Automatic with Pt 1000/NTC (30 k
-5 ... 99.9 °C
W)
Manual input -20 ... 130 °C resolution 1K
79
Overview
Connectors
Input amplifier
Calibration modes
Electrodes Socket acc. to DIN 19 262 or BNC
4-mm socket for reference electode Temp. probe 4-mm socket for temperature probe Interface/
analog output
Bidirectional RS 232 interface or ana-
log output with autom. recognition of
the PC, printer, or recorder connected Plug-in power
2 pole special Friwo supply (option)
12
10
-12
W
A
Input impedance 10 Offset current
AutoCal TEC With Technical buffers, pH values
2.00; 4.00; 7.00; 10.00 at 25 °C;
buffers are temperature compensa-
ted in the range 0 ... 90 °C AutoCal DIN With standard buffers according to
DIN 19 266/NIST, pH values:
1.68; 4.01; 6.87; 9.18 at 25 °C;
buffers are temperature compensa-
ted in the range 0 ... 90 °C ConCal With any buffers; one and two-point
calibration, manual acceptance of
measured values and temp. input
80
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 electrodes, etc.
81
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 section 1.5 T
ECHNICAL DATA 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 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
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.
82
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.
83
Safety
84
Commissioning

3 Commissioning

Perform the following activities for the initial commissioning:
l Set the date and time l Connect the plug-in power supply.
Setting the date
and time
1 Press and hold down the <pH> key. 2 Press the <on/off> key.
The
display test
appears briefly on the display. The measuring instrument then switches automati­cally to the setting of the baud rate.
3 Press the <run/enter> key repeatedly until the date
flashes on the display.
4 Set today’s date by pressing <
▲> <▼>.
5 Confirm with <run/enter>.
The date (month) flashes on the display.
6 Set the current month by pressing <
▲> <▼>.
7 Confirm with <run/enter>.
The year appears on the display.
8 Set the current year by pressing <
▲> <▼>.
9 Confirm with <run/enter>.
The hour field flashes on the display.
10 Set the current time by pressing <
▲> <▼>
11 Confirm with <run/enter>.
The minutes field flashes on the display.
12 Set the current time by pressing <
▲> <▼>
13 Confirm with <run/enter>.
The measuring instrument then switches to the pH measuring mode automatically.
85
Commissioning
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).
2 1
3
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.
Note
You can also perform measurements without a plug-in pow­er supply.
86
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.
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:
appears briefly on the display.
l if the power is supplied by the plug-in power supply l if the l if the communication cable is connected l if the recorder cable is connected l if the printer cable is connected
AutoStore
function is active
(for external printers)
87
Operation

4.2 Measuring

Preparatory
activities
Perform the following preparatory activities when you want to measure:
1 Connect the 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 electrode
according to section 4.3 C
ALIBRATING.
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.
Caution
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.
88
Operation
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.
1 Determine the current temperature using an external
thermometer.
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.
89
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
pH
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 (response time: > 30 s)
1 Call up the pH measuring mode by pressing <pH>.
90
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. This measured value is transmitted to the RS interface.
4 If necessary, start the next AutoRead measurement
by pressing <run/enter>.
5 To cancel 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.
91
Operation
4.2.3 Transmitting measured values
You can transmit measured values (data records) in 3 ways:
l Switch on the data transmission (Int 2) (see 114)
– After expiry of the selected interval, the current data
record is sent to the RS interface.
l Switch on AutoStore (Int 1) (see section 4.4.2 SWITCHING
ON AUTOSTORE (INT 1) 108)
– After expiry of the selected interval, the current data
record is sent to the RS interface and in addition is stored in the data store of the instrument
– AutoStore (Int 1) covers the
data transmission
interval
(Int 2).
l Press the <run/enter> key
This manually triggers a transmitting of the current mea­sured values at any time - independently of the selected intervals.
Note
If you connect a recorder (analog output), both the output to the digital output are switched off.
92
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.
When to calibrate?
AutoCal TEC is specially adapted to the Technical buffer solutions as a
AutoCal DIN is specially adapted to permanently programmed buffer
l After connecting another electrode l When the sensor symbol flashes:
– after expiry of the calibration interval – after a voltage interruption, e.g. battery change
You can choose between 3 calibration procedures:
fully automatic two or three-point calibration. The buffer solutions are automatically recognized by the instrument. The following pH values are available:
2.00, 4.00, 7.00, 10.00.
solutions according to DIN 19266 as a fully automatic two or three-point calibration. The buffer solutions are automati­cally recognized by the instrument. The following pH 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
AutoRead
function is automatically activated. The current AutoRead measurement (with acceptance of the current value) can be terminated at any time by pressing
<run/enter>.
93
Operation
Calibration protocol The calibration protocol contains the cal ibr ati on dat a of the
current calibration. You can call up the calibration protocol by outputting the data storage (section 4.4.3).
Note
You can automatically print out a calibration protocol after the calibration. To do so, connect a printer according to sec­tion section 4.5.3 before the calibration. After a valid calibra­tion, the protocol is printed.
Sample printout:
CALIBRATION PROTOCOL
02.03.99 14:19 Device No.: 12345678 CALIBRATION pH Cal Time: 01.03.99 / 15:20 Cal Interval: 7d AutoCal DIN Tauto Buffer 1 1.679 Buffer 2 4.008 * Buffer 3 6.865 Buffer 4 9.180 *
C1 174.1mV 25.0°C C2 -133.3mV 25.0°C S1 -59.4 mV/pH ASY1 - 4 mV Probe: +++
94
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.
95
Operation
4.3.1 Calibration interval (Int 3)
The flashing sensor symbol reminds you to calibrate regu­larly. After the selected calibration interval (Int 3) expires, the sensor symbol flashes. Measurements can continue.
Note
To ensure the high measuring precision of the measuring system, perform a calibration after the calibration interval expires.
Setting the calibra-
tion interval
The calibration interval (Int 3) is set to 7 days in the factory. The interval can be changed (1 ... 999 days):
1 Switch off the instrument. 2 Press <pH> and hold down the key. 3 Press the <on/off> key.
The
display test
appears briefly on the display. The instrument then switches automatically to the configuration level.
Int 3
4 Press the <run/enter> key until
appears on the
display.
96
5 Press <▲> <▼> to set the required time interval until
the next calibration.
6 Confirm with <run/enter>. 7 Change to the measuring mode by pressing <pH>.
Operation
4.3.2 AutoCal TEC
Use any two or three of the Technical buffer solutions for this procedure in increasing or decreasing order.
Note
Steps 2, 6 and 13 are not required if you use a temperature probe.
1 Press the <CAL> key repeatedly until
AutoCal TEC
function display appears.
Ct1
and the
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
ap-
pears.
.
5 Thoroughly rinse the electrode with distilled water.
97
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 or continue with three-point calibration.
98
Operation
Three-point
calibration
11 Press the <run/enter> key.
Ct3
appears on the display. 12 Thoroughly rinse the electrode with distilled water. 13 If necessary, set the temperature of the third buffer
solution by pressing <
▲> <▼>.
14 Submerse the electrode in the third buffer solution. 15 Press the <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 three-point calibration. The value of the slope (mV/pH) appears on the dis­play.
16 Press the <run/enter> key.
The value of the asymmetry (mV) appears on the dis­play.
17 To return to the measuring mode: Press the <pH>
key.
Note
You can also prematurely terminate the three-point calibra­tion by pressing <pH>. The values of the two-point calibra­tion for the slope and asymmetry are then stored.
99
Operation
4.3.3 AutoCal DIN
Use two or three different DIN buffer solutions for this proce­dure in increasing or decreasing order.
DIN buffer solution pH
A 1.68 C 4.01 D 6.87 F 9.18
Note
Steps 2, 6 and 13 are not required if you use a temperature probe.
1 Press the <CAL> key repeatedly until
AutoCal DIN
function display appear.
Cd1
and the
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
ap-
pears.
100
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.
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 or continue with the three-point calibration.
101
Operation
Three-point
calibration
11 Press the <run/enter> key.
Cd3
appears on the display. 12 Thoroughly rinse the electrode with distilled water. 13 If necessary, set the temperature of the third buffer
solution by pressing <
▲> <▼>.
14 Submerse the electrode in the third buffer solution. 15 Press the <run/enter> key.
AR
flashes on the display.
The electrode voltage (mV) appears on the display.
AR
As soon as a stable value is recognized,
disap­pears. The sensor symbol shows the electrode evaluation after the three-point calibration. The value of the slope (mV/pH) appears on the dis­play.
16 Press the <run/enter> key.
The value of the asymmetry appears on the display (mV).
17 To return to the measuring mode: Press the <pH>
key.
Note
You can also prematurely terminate the three-point calibra­tion by pressing <pH>. The values of the two-point calibra­tion for slope and asymmetry are then retained.
102
4.3.4 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
ConCal
function display appear.
ASY
and the
2 If necessary, set the temperature of the buffer solu-
tion by pressing <
▲> <▼>.
3 Submerse the pH electrode in the first buffer solution
pH 7.0 ± 0.5.
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.
103
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.
104
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 message indicates an active temperature measurement.
1 Press the <CAL> key repeatedly until
ConCal
function display appear.
ASY
and the
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 asym-
metry (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.
105
Operation

4.4 Storing

The pH meter has an internal data storage device. Up to 200 data records can be stored in it. A complete data record consists of:
l Memory location l Date l Time l Measured value l Temperature l Temperature measurement procedure l I.D. number
You can transmit measured values (data records) to the data storage in 2 ways:
l Manual storage l Switching on the AutoStore function (Int 1).
4.4.1 Manual storage
You can transmit a measured value to the data storage as follows:
1 Press the <STO> key.
The current number of the next free memory location appears on the display.
106
Operation
2 Confirm with <run/enter>.
The display changes to the input of the I.D. number.
3 Enter the required I.D. number (1 ... 999) by pressing
▲> <▼>.
<
4 Confirm with <run/enter>.
The instrument changes to the measuring mode.
*(+,, message This message appears if all 200 memory locations are full.
You have the following options:
Store the current measured value. The oldest measured value (memory
Press <run/enter>
location 1) is overwritten by this Return to the measuring mode without
Press any key
storing Output the data storage See section
4.4.3
Delete the data storage See section
4.4.4
107
Operation
4.4.2 Switching on AutoStore (Int 1)
The storage interval (Int 1) determines the time interval between automatic storage processes. After the time interval expires, the current data record is transmitted to the data storage and to the RS interface.
Setting the storage
interval
The storage interval (Int 1) is set to OFF in the factory. Thus, the
AutoStore
function is switched off. To switch the function on, set up a time interval (5 s, 10 s, 30 s, 1 min, 5 min, 10 min, 15 min, 30 min, 60 min):
1 Press and hold down the <run/enter> key.
Int.1
2 Press the <STO> key.
appears on the display.
3 Press the <▲> <▼> keys to set up the required time
interval between storage processes.
108
4 Confirm with <run/enter>.
The number of free memory locations appears on the display.
Operation
5 As soon as all 200 memory locations are full, the
AutoStore function is terminated (Int 1 = OFF). If too few storage locations are available for your measurements:
– backup the data storage (see 110) and – clear the data stored (see 113).
6 Confirm with <run/enter>.
The prompt for the I.D. number appears on the dis­play.
Switching off the
AutoStore
7 Press <▲> <▼> to set the required I.D. number. 8 Confirm with <run/enter>.
The instrument changes to the pH measuring mode and starts the measuring and storage procedure.
AutoStore
flashes on the display.
Note
The
AutoStore
function is interrupted if you perform other functions, e.g. output data storage. After completing the other function, the
AutoStore
function continues. However, as a result, gaps can occur in the recording of the measured values.
Switch off the
l Setting the storage interval (Int 1) to OFF or l Switch the pH meter off and on again.
AutoStore
function by:
109
Operation
4.4.3 Outputting the data storage
The contents of the data storage can be output to the:
l display l RS interface
Outputting to the
display
1 Press the <RCL> key repeatedly until
pears on the display.
2 Press the <run/enter> key.
A measured value appears on the display. The memory location of the data store appears for approx. 2 s. This is followed by the corresponding temperature.
You can perform the following activities:
Sto disp
ap-
110
Display further parameters of the data record (I.D. no., date, time, memory loca-
Press <run/enter>
tion) Advance one data record (memory location) Press < Go back one data record (memory location) Press <
▲> ▼>
Note
If you want to find a specific parameter (e.g. date), proceed as follows:
Operation
1 Select the parameter (e.g. date) by pressing <run/
enter>.
Outputting to
RS interface
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 <RCL> key repeatedly until
Sto SEr
pears on the display.
ap-
2 Press the <run/enter> key.
Sto CAL
appears on the display. The calibration pro­tocol is transmitted to the RS interface. Following the calibration protocol, the complete con­tents of the storage is transmitted to the RS interface.
Note You can the cancel the transmission by pressing <pH> or <run/enter>.
111
Operation
Sample printout:
CALIBRATION PROTOCOL
02.03.99 14:19 Device No.: 12345678 CALIBRATION pH Cal Time: 01.03.99 / 15:20 Cal Interval: 7d AutoCal DIN Tauto Buffer 1 1.679 Buffer 2 4.008 * Buffer 3 6.865 Buffer 4 9.180 *
C1 174.1mV 25.0°C C2 -133.3mV 25.0°C S1 -59.4 mV/pH ASY1 - 4 mV Probe: +++
No. 1:
09.03.99 17:10 pH 10.01 25 °C Tman AR Ident : 1
No. 2:
09.03.99 17:11 pH 10.01 24,7 °C Tauto AR Ident : 1
No. 3:
09.03.99 17:12 305 mV Tauto Ident : 13
The printout contains:
l calibration protocol l storage contents
112
Operation
4.4.4 Clearing the storage
This function can erase the stored data records. 200 mem­ory locations will then become available again.
Note
Clear store
The
function only appears if data records have already been stored in the storage. Otherwise, the pH meter automatically changes to the measuring mode.
In order to delete all the data records, proceed as follows:
1 Switch off the instrument. 2 Press and hold down the <STO> key. 3 Press the <on/off> key.
The
display test
appears briefly on the display.
4 Confirm the clearing process by pressing <run/
enter>. Pressing any other key stops the clearing process and the data records remain in the storage.
Note
The calibration data remain in the storage and can be called up via the calibration protocol.
113
Operation

4.5 Data transmission

You can use the following options to transmit data:
l One of the following options:
– The
AutoStore
storage interval) save measured values internally
1
function (108) is used to periodically (
Int
and output them on the RS interface.
– The
data transmission interval (Int 2)
function is used to periodically output measured values to a RS interface (see below).
l The
Output data store
function (110) is used to output cal­ibration data and stored measured values to the RS inter­face.
l The analog recorder output (116) is used to output mea-
sured values as voltages.
4.5.1 Data transmission interval (Int 2)
The interval for the data transmission (Int 2) is determined by the time interval between automatic data transmissions. After the time interval expires, the current data record is transmitted to the RS interface.
114
Note
The setting of the interval (Int 2) only has an effect when the storage interval (
AutoStore
function) is switched off.
Operation
Setting the
data transmission
interval
The interval is set to OFF in the factory. To start the data transmission, set up an interval (5 s, 10 s, 30 s, 1 min, 5 min, 10 min, 15 min, 30 min, 60 min):
1 Press and hold down the <run/enter> key. 2 Press the <auto read> key.
Int 2
appears on the display.
3 Press <▲> <▼> to set up the required time interval
between storage processes.
4 Confirm with <run/enter>.
The instrument changes automatically to the pH measuring mode.
Note
If the
AutoStore
function is active, the data transmission is performed according to the setting of the storage interval (Int1). Set the storage interval (Int 1) to OFF to activate the
data transmission
interval (Int 2).
Note
You can also set the
Configuration
menu (see 118).
data transmission
interval (Int 2) in the
115
Operation
4
4.5.2 Recorder (analog output)
You can transmit the data to a recorder via the analog out­put. Connect the analog output to the recorder via the Z394 RS interface cable. The data output switches automatically to
recorder output
.
Socket assignment
1 Free
1
RS 232
REC
2
3
2 Plug coding 3 Ground 4 Analog output
low impedance electrode signal corresponds to 50 ... 62 mV/pH (internal resistance < 5 Ohm)
Note
Activate the analog output by connecting 2 and 3.
116
Operation
4
4.5.3 PC/external printer (RS232 interface)
You can transmit data to a PC or an external printer via the RS232 interface. Connect the RS interface to the instrument via the Z395 cable (PC) or Z391 cable (external printer). The data output switches automatically to
RS232
.
Note
The RS232 interface is not galvanically isolated. If it is connected to an earthed PC/printer, measurements cannot be made in earthed media as this would give incor­rect results!
Set up the following transmission data on the PC/printer:
Socket assignment
Baud rate Selectable between:
1200, 2400, 4800, 9600 Handshake RTS/CTS + Xon/Xoff PC only: Parity None Data bits 8 Stop bits 1
1 CTS
1
RS 232
REC
2
3
2 RxD 3 Ground 4TxD
117
Operation

4.6 Configuration

You can adapt the pH meter to your individual requirements. To do this, the following parameters can be changed (the status on delivery is marked in bold):
Baud rate 1200, 2400, 4800, 9600 Data transmission
interval (Int 2)
OFF, 5 s, 10 s, 30 s, 1 min, 5 min, 10 min, 15 min, 30 min,
60 min Calibration interval (Int 3) 1 ... 7 ... 999 d Temperature unit °C, °F
Date/time As required Resolution of pH display 0.01, 0.001
Note
You can leave the configuration menu at any time. Parame­ters that have already been changed are stored. To do this, press the <pH> key.
1 Switch off the instrument. 2 Press and hold down the <pH> key. 3 Press the <on/off> key.
The display test
appears briefly on the display. The instrument then switches automatically to the setting of the baud rate.
118
Baud rate
Data transmission
interval
Operation
4 Set up the required baud rate by pressing <▲> <▼>. 5 Confirm with <run/enter>.
Int 2
appears on the display.
Calibration
interval
6 Set up the required time interval by pressing
▲><▼>.
<
7 Confirm with <run/enter>.
Int 3
appears on the display.
119
Operation
Temperature unit
8 Set up the required time interval by pressing
▲><▼>.
<
9 Confirm with <run/enter>.
USE °C
appears on the display.
Date and time
10 Change between °C and °F by pressing <▲> <▼>. 11 Confirm with <run/enter>.
The date flashes on the display.
12 Set today’s date by pressing <▲> <▼>. 13 Confirm with <run/enter>.
The date (month) flashes on the display.
120
14 Set the current month by pressing <▲> <▼>. 15 Confirm with <run/enter>.
The year appears on the display.
16 Set the current year by pressing <▲> <▼>. 17 Confirm with <run/enter>.
The hours flash on the display. 18 Set the current time by pressing <▲> <▼>. 19 Confirm with <run/enter>.
The minutes flash on the screen. 20 Set the current time by pressing <▲> <▼>. 21 Confirm with <run/enter>.
The instrument changes automatically to the pH
measuring mode.
Operation
Adjusting the reso-
lution
1 Press and hold down the <run/enter> key. 2 Press the <pH> key.
The measured values appear with the higher resolu-
tion on the display, e.g. pH = 4.012.
3 Press the <run/enter> key and <pH> key again.
The measured values with the lower resolution ap-
pear on the display, e.g. pH = 4.01.
121
Operation

4.7 Reset

You can reset (initialize) measuring and configuration parameters separately from one another.
Measuring parame-
ters
The following measuring parameters (pH InI) are reset to the values 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
Note
When the measuring parameters are reset, the calibration data are lost. After the parameters have been reset, cali­brate!
Configuration
parameters
The following configuration parameters (InI) are reset to the values they had on delivery:
Baud rate 4800 Interval 1
(automatic storing) OFF Interval 2
(for data transmission) OFF
122
Resetting measur-
ing parameters
Operation
1 Press and hold down the <run/enter> key. 2 Press the <CAL> key.
3 Use <▲> <▼> to toggle between no and yes.
yes: reset measuring parameters.
no: retain settings.
Resetting configura-
tion parameters
4 Confirm with <run/enter>.
The instrument changes to the configuration param-
eters.
5 Toggle between no and yes by pressing <▲> <▼>.
yes: reset configuration parameters.
no: retain settings.
6 Confirm with <run/enter>.
The instrument changes automatically to the pH
measuring mode.
123
Operation
124
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 batteries from the battery compartment 3 Insert four new batteries (Type Mignon AA) into the
battery compartment.
4 Close the battery compartment (1).
The date (day) flashes on the display.
5 Set up date/time accordi ng chapter 3 COMMISSIONING.
1
.
Caution
Make sure that the poles of the batteries are the right way round. The spond to the Only use leakproof alkaline manganese batteries.
Note
See the relevant operating manual of the electrode for in­structions on maintenance.
± signs in the battery compartment must corre-
± signs on the batteries.
125
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. It 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
126
Error message,
What to do if...

6 What to do if...

Cause Remedy
I/
Error message,

pH electrode:
– Not connected – Connect electrode – Air bubbles in front of the
– Remove air bubbles
diaphragm
– Air in the diaphragm – Extract air or
moisten diaphragm – Cable broken – Replace electrode – Gel electrolyte dried out – Replace electrode
Cause Remedy
pH electrode: – Diaphragm contaminated – Clean diaphragm – Membrane contaminated – Clean membrane – Moisture in the plug – Dry plug – Electrolyte obsolete – Replace electrode – Electrode obsolete – Replace electrode – Electrode broken – Replace electrode
Measuring instrument: – Incorrect calibration
procedure
– Incorrect solution
temperature (without
– Select correct
procedure
– Set up correct
temperature
temperature probe)
– Socket damp – Dry socket
127
What to do if...
No stable
measured value
Buffer solutions:
– Incorrect buffer solutions – Change calibration
procedure
– Buffer solutions too old – Only use once.
Note the shelf life
– Buffer solutions depleted – Change solutions
Cause Remedy
pH electrode: – Diaphragm contaminated – Clean diaphragm – Membrane contaminated – Clean membrane
Sensor symbol
flashes
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 – Organic liquids – Use suitable electrode
Cause Remedy
– Calibrating interval
expired
– Newly calibrate measuring
system
128
Cause Remedy
What to do if...
LoBat display
*( display
Obviously incorrect
measured values
– Batteries almost
depleted
– Replace batteries
(see section 5.1 MAINTENANCE)
Cause Remedy
– Timeout of the interface – Checkout connected
instrument
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
Instrument does not
react to keystroke
*(+,, message
Cause Remedy
– Operating state
undefined or EMC electric stress unallowed
– Processor reset:
Press the <auto read> key and switch on instrument
Cause Remedy
– All 200 memory locations
are full
– Output data store and
clear data store
129
What to do if...
130
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.
131
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 disp Display
Displays the data storage on the screen E3 Error message (see chapter 6 W
IF...)
HAT TO DO
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
132
OFL Overflow
Display range exceeded pH pH value
RCL Recall
memory dump S Slope SELV Safety Extra Low Voltage SEr Serial interface
Output of the data storage on the RS 232
or on the internal printer SLO Slope
Slope setting on calibration Sto Store
Memory TP Temperature probe
Temperature measurement active
Lists
U
ASY Asymmetry potential
°C Temperature unit, °Celsius °F Temperature unit, Fahrenheit
133
Lists
Glossary
Asymmetry Zero point of a pH electrode.
Resolution Number of decimal places that appear for a measured
value.
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.
Baud rate Transmission rate in bits/s.
Diaphragm Contact point between the reference electrolytic solution
and the sample.
Drift control See A
UTOREAD.
Test sample Sample to be measured (can be liquid or solid).
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.
134
Index
Lists
A
analog output 116 asymmetry 93 authorized use 82 AutoCal DIN 93, 100 AutoCal TEC 93, 97 AutoRead 90
B
battery compartment 125 baud rate
setting
119
C
calibrating 93 calibration
evaluation interval 96 procedures 93
protocol 94 ConCal 93, 103 condition on delivery 122
95
D
data record 106 data transmission (interval) 115 date
setting display 75 drift control 90
85, 120
calibration data transmission 114 storing 108
96
K
keys 74
L
LoBat 129
M
measuring precision 96
O
operational safety 82
P
place of the instrument 87 plug-in power supply 86 power supply 79, 86 printing
calibration protocol measured values 92
printing measured values 92
94
R
Redox electrode 91 Redox voltage 91 replacing the batteries 125 reset 122 RS232 interface 117
E
energy saving feature 87 error messages 127
I
initialize 122 interval
S
safety 81 safety precautions 81 single-point calibration 93
ConCal 105
slope 93
135
Lists
sockets 75
T
temperature probe 89 three-point calibration 93
AutoCal DIN 102 AutoCal TEC 99
time
setting
two-point calibration 93
AutoCal DIN 101 AutoCal TEC 98 ConCal 103
85, 120
136
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