Knick 765 User manual

Instruction Manual
765 Laboratory pH Meter

TA-167.000-KNE04 051009 Software version: 4.x
Subject to change without notice
Elektronische Meßgeräte
GmbH & Co.
P.O.Box 37 04 15
D-14134 Berlin
Germany
Tel: [phone]
Fax: [phone]
www.knick.de
[email protected]
Warranty
Defects occurring within 3 years from delivery
date shall be remedied free of charge at our
works (carriage and insurance paid by sender).
Accessories: 1 year

The 765 Laboratory pH Meter I
Contents
Information on this instruction manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . II
Safety information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . III
EC Declaration of Conformity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . IV
1 The 765 Laboratory pH Meter
Package contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Short device description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
2 Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Meter design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
General information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Power-on and start-up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Parameter level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Calibration level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Diagnostics level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Trueline®recorder output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Serial interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Standard settings for ZU 0244 Lab Printer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Command set for the serial interface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
3 Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Error messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Appendix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Product line . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Buffer tables. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

II Information
765 Laboratory pH Meter
Information on this instruction manual
Warnings and notes
Instructions marked with this sign must be strictly
observed for reasons of your own safety! Failure to
follow these instructions may result in injuries.
Notes provide important information that should be
strictly followed when using the device.
Typical representations
Display example
A gray representation of the display text indicates a
flashing display.
Keys whose functions are described.
Markings in the text
Keys are represented by bold-faced text,
e.g. , , , , , , ... , .
on/standby

Information III
Safety information
Be sure to read and observe the following instructions!
Before connecting the device to the power supply, make sure that the voltage corre-
sponds with the rating given on the rating plate of the device.
Opening the device exposes live parts. Therefore, it shall not be opened. If a repair
should be required, return the device to our factory.
If opening the device is inevitable, it shall first be disconnected from all voltage
sources. Make sure that the mains supply has been disconnected.
Repair or adjustment of an opened device under voltage shall be carried out only by
a skilled person who is aware of the hazards involved.
Remember that the voltage across accessible parts of the open device may be dan-
gerous to life.
Whenever it is likely that the protection has been impaired, the device shall be made
inoperative and secured against unintended operation.
The protection is likely to be impaired if, for example:
• the device shows visible damage
• the device fails to perform the intended measurements
• after prolonged storage at temperatures above 70°C
• after severe transport stresses
Before recommissioning the device, a professional routine test in accordance with
EN 61010-1 must be performed. This test should be carried out at our factory.

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Operation 1
The 765 Laboratory pH Meter
Package contents
After unpacking, please check the shipment for
completeness. The package should contain:
• 765 Laboratory pH Meter
• Power cord
• This instruction manual
Short device description
•The Model 765 is used for pH and ORP measure-
ments in the laboratory.
• Temperature compensation is automatic using a
Pt 100 or Pt 1000 temperature probe or manual by
entering the temperature.
• Buffer solutions of eleven different, selectable
buffer sets are provided for calibration. Buffer rec-
ognition is automatic via Calimatic®.
• The calibration timer alerts you when the preset
interval between two calibrations has expired.
• Sensoface®electrode monitoring checks the con-
nected electrode and provides information on the
electrode condition.
• Knick Fullcheck®device self-test checks the
device functions at the press of a key.
• Records of parameter setting, calibration and
diagnostics are particularly helpful for QM docu-
mentation to ISO 9000 and GLP. The records can
be directly output to a standard printer via the inte-
grated serial interface.

765 Laboratory pH Meter
2 Operation
2 Operation
Meter design
1, 2 Electrode connection
3, 4 Temperature probe connection
5 DS connection
6, 7 Recorder output
8 Interface connection
9 Power input
10 Sensoface®display
11, 13 Displays
12, 14 Measurement symbols

Operation 3
General information
Keypad
Pressing turns the pH meter on or
switches to standby mode. Standby mode is indi-
cated by a lighted Sensoface®status display or two
measurement symbols. At power-on, the pH meter
automatically performs a short self test and then
goes to measuring mode.
Pressing opens the Calibration level. On the
Calibration level the pH meter is adapted to the
electrode. You can conduct either a one or a two-
point calibration.
Pressing opens the Parameter level. On the
Parameter level all variable device parameters are
set.
• In the VIEW menu you can view all parameters.
• In the EDIT menu you can also edit the parame-
ters.
Pressing opens the Diagnostics level. On the
Diagnostics level you can get information on the
electrode condition, view the current electrode
data, and perform a complete device self test.
• The Sensoface®menu lists the individual param-
eters of Sensoface®automatic electrode monitor-
ing with the corresponding evaluations.
• The Electrode Data menu shows the values for
zero and slope of the electrode determined during
last calibration, the remaining time until the next
due calibration determined by the calibration timer
and the data of the electrode statistics.
• With the Knick Fullcheck®menu, a complete
device self-test is performed.
on/standby
cal
par
diag

765 Laboratory pH Meter
4 Operation
Pressing stores an entered parameter. If
you have not made any changes, pressing
selects the next parameter (instead of ).
Pressing exits a function level and returns
you to measuring mode.
Pressing in measuring mode prints out the
current pH, mV and temperature values with date
and time. Pressing on one of the function
levels prints out a complete record of the data
stored.
• Pressing or in measuring mode selects the
measured variable for the left or right display,
respectively. The corresponding measurement
symbol appears on the right side of the display.
• On the function levels these keys are used to
select parameters.
• When entering numerical parameters, they are
used to increment or decrement a numeral.
• Pressing in the EDIT menu of the Parameter
level selects the parameter you want to edit.
• Pressing this key in the VIEW menu or on the
Diagnostics level stops automatic line scrolling.
enter
meas
print

Operation 5
Menu structure
Sensoface®automatic
electrode monitoring
Sensoface®automatic electrode monitoring pro-
vides information on the electrode condition. Zero
point, slope and response time are evaluated dur-
ing calibration.
Impedance, dry-out and the calibration timer are
evaluated during measurement and in standby
mode.
A summary of the individual results is expressed by
three face symbols.
The electrode is in good condition.
The electrode is still usable, but should be cali-
brated.
The electrode urgently requires calibration. If the
display does not change after calibration, replace
the electrode.

765 Laboratory pH Meter
6 Operation
More detailed information on the indicated elec-
trode condition and the individual parameter evalu-
ations is given in chapter ”Diagnostics level” (see
Pg. 21).
Sensoface®was specially designed for monitoring
pH electrodes. Since ORP electrodes have com-
pletely different characteristics, they provoke
invalid Sensoface®displays. Therefore, you should
disable Sensoface®for ORP measurements.
Sensoface®display can also be degraded when
you use a pH simulator.
Power-on and start-up
Mains supply The pH meter is designed for 230 VAC supply
(Option 363: 115 V AC). Connect the power input of
the pH meter to a mains outlet using the included
power cord.
If the pH meter is disconnected from mains, clock
and calibration timer are not affected (reserve
power approx. 1 year). Settings, calibration and
diagnostics data remain permanently stored.
Electrode connection The pH meter can be combined with commercial
electrodes: with nominal zero at pH 7 and with
• standard coaxial plug to DIN 19 262 and/or
•4mm banana plug.
For special electrodes with differing specifications,
we offer Option 346 (nominal zero and slope of
electrode user defined).

Operation 7
Connection Socket
Combination electrode 1
Single sensing electrode 1
Single reference electrode 2
Temp probe of combination electrodes 3
(Electrodes with integrated temp probe)
Separate temperature probe 3, 4
If no temperature probe is connected, the meter
uses the manually selected temperature. The deci-
mal point of the temperature display flashes.
If you use double platinum electrodes for voltamet-
rical indication of titrations:
•Connect the banana plugs of the double platinum
electrode to sockets 1 and 2.
• To connect the 10 µA polarization current to the
double platinum electrode, connect socket 5 with
the inner pole of socket 1 (e.g. using a banana
plug with cross hole).
For the RS 232 interface, a shielded cable must be
used (e.g. ZU 0152, ZU 0153).

765 Laboratory pH Meter
8 Operation
Standby mode If the meter is connected to a mains outlet but not
switched on, it is in standby mode. This indicated by
a lighted Sensoface®display.
If Sensoface®display is turned off, two measure-
ment symbols are lighting.
Clock and calibration timer are running in standby
mode. Knick Drycheck®and impedance monitoring
are active. Settings, calibration and diagnostics
data remain permanently stored. The interface is
deactivated.
Pressing switches the meter to mea-
suring mode.
At power-on, the meter performs a short check:
•Simultaneous lighting-up of all display segments,
measurement symbols and Sensoface®displays
• Display of model name PH 765
• Display of software version
•Display of nominal buffer values of selected buffer
set
• Memory test
To stop the short check, press .
Do not disconnect the meter from mains if you do
not use it. Only when the meter remains in standby
mode can the electrode be monitored and the bat-
tery for the clock be charged.
on/standby

Operation 9
Measuring mode In measuring mode both displays indicate the
respectively selected measured variable. The vari-
able for the left display is selected using , for the
right display using . The corresponding mea-
surement symbol is shown on the right side of the
display. You can choose any of the following vari-
ables:
• pH value
• Electrode potential [mV]
• Temperature [°C]
• Time
A flashing point on the temperature display indi-
cates that no temperature probe is connected. The
meter now uses the manually selected tempera-
ture.
If you have connected a printer, pressing in
the measuring mode gives you a printout of the cur-
rently measured values with date and time.
print

765 Laboratory pH Meter
10 Operation
Parameter level
On the Parameter level all variable device parame-
ters are set. Parameters are set in dialog mode
using different menus.
Activating parameter setting Press to exit measuring mode and access the
main menu of the Parameter level. To exit Parame-
ter level, press . It is exited automatically
when all parameter setting steps have run through.
Main menu In the main menu of the Parameter level you select
the desired submenu using or . Press-
ing confirms your choice and gives access
to the corresponding submenu.
The VIEW menu automatically displays all parame-
ters . Settings cannot be changed, however.
• To hold the display, press .
• To scroll one line forwards or backwards, press
or , respectively.
In the EDIT menu you can view and edit all param-
eters.
•Select the parameter you want to edit using or
.
• Press to start parameter editing. To indicate
that the parameter can now be edited, the right
display flashes.
•While the right display is flashing, you can edit the
parameter using and . When entering
numerical values, select the position using and
then count up or down using or .
• Confirm with . The selected value will be
stored and the next parameter displayed.
•You can now select the next parameter using
or or press to exit the Parameter level.
par

Operation 11
Typical setting procedure The meter is factory set to calibration buffer set 01
(Mettler Toledo technical trade buffers). However,
you want to calibrate using the technical buffer
solutions to DIN 19 267, calibration buffer set 03.
Therefore, you must select buffer set 03 on the
Parameter level.
Press to access the Parameter level.
Press to select the EDIT menu.
Press to open the EDIT menu.
Select buffer set parameter BUFF using .
Now press to change the buffer set. The right
display will flash.
Select buffer set 03, technical buffers to
DIN 19 267, using .
par
enter

765 Laboratory pH Meter
12 Operation
Press to confirm your choice. Buffer set 03
will be stored and the next parameter displayed.
Press to exit Parameter level.
Printout of parameter record If you have connected the pH meter to a printer, you
can print out all stored parameter settings.
Press to open the Parameter level.
Press to print out all settings. The meter will
automatically return to measuring mode.
Parameters In the following, the individual parameters and their
possible settings will be explained.
Manual temperature (–50 to +150 °C)
If no temperature probe is connected, the meter
uses the manually selected temperature. In this
case, the decimal point of the temperature display
will flash in measuring mode.
Sensoface®(off / on)
Display of Sensoface®electrode monitoring can be
turned on or off. If Sensoface®display is turned off,
standby mode is indicated by two lighted measure-
ment symbols. Display of Sensoface®parameters
on the Diagnostics level is not affected.
For information on Sensoface®, refer to chapter
”Sensoface®menu” (Pg. 22).
enter
meas
print

Operation 13
Sensoface®was specially designed for monitoring
pH electrodes. Since ORP electrodes have com-
pletely different characteristics, they provoke
invalid Sensoface®displays. Therefore, you should
disable Sensoface®for ORP measurements. Sen-
soface®display can also be degraded when you
use a pH simulator.
Displaymatic®(off / on)
Displaymatic®can be turned on or off. Display-
matic®ensures a stable measured value display in
case of rapid changes of the pH value. This allows
for easy reading of the value. It is achieved by sup-
pressing the two running digits behind the decimal
point. When the value changes slowly, only the last
digit will be suppressed. When the value has stabi-
lized, all digits will be displayed.
Only for meters
with Option 346:
Setting the nominal electrode zero point and slope:
Nominal zero (pH 0.00 to 14.00)
For special electrodes with differing nominal zero.
The entered zero point is taken as reference for
Calimatic®. The exact zero point will be determined
during calibration.
Nominal slope (25.0 to 61.0 mV/pH)
For special electrodes with differing nominal slope.
The entered slope is taken as reference for Cali-
matic®. The exact slope will be determined during
calibration.
Isothermal potential (–500 to +500 mV)
The isothermal potential entered here is automati-
cally taken into account for calibration and pH
determination.

765 Laboratory pH Meter
14 Operation
Calibration buffer set (00 to 10)
Select the buffer set with the buffer solutions you
are using. The meter has stored eleven different
calibration buffer sets.
(see Buffer sets Pg. 49).
The meter can only operate properly when the
buffer solutions used correspond to the selected,
activated buffer set.
Other buffer solutions, even those with the same
nominal values, may demonstrate a different tem-
perature behavior.
This leads to measurement errors.
BUFF –00– Knick technical buffers
pH 2.00 4.01 7.00 9.21 (25°C
BUFF –01– Mettler-Toledo technical buffers (correspond to Ingold technical buffers)
pH 2.00 4.01 7.00 9.21 (25°C)
BUFF –02– Merck/Riedel
pH 2.00 4.00 7.00 9.00 12.00 (20 °C)
BUFF –03– DIN19267
pH 1.09 3.06 4.65 6.79 9.23 12.75 (25°C)
BUFF –04– DIN19266 and NIST (NBS)
pH 1.679 4.006 6.865 9.180 12.454 (25°C)
BUFF –05– Merck/Riedel
pH 1.00 3.00 6.00 8.00 10.00 13.00 (20°C)
BUFF –06– Merck
pH 4.66 6.88 9.22 (20°C)
BUFF –07– Ciba(94)
pH 2.06 4.00 7.00 10.00
BUFF –08– customer specific
pH 2.00 4.62 7.00 8.20 10.00 12.00 (20°C)
BUFF –09– customer specific
pH 2.00 4.01 7.00 9.21 12.00 (25 °C/20 °C)
BUFF -10– Mettler Toledo (USA)
pH 4.00 7.00 10.01 (25 °C)