OHAUS AB23PH User manual

a-AB23PH
Bench pH Meter
Instruction Manual

AB23PH Bench pH Meter EN-1
Contents
1. INTRODUCTION .......................................................................................................... 2
1.1. SAFETY PRECAUTIONS......................................................................................................... 2
1.2. INTENDED USE.................................................................................................................. 3
1.3. DISPLAY AND CONTROLS ..................................................................................................... 4
2. INSTALLATION ............................................................................................................ 6
2.1 INSTALL THE STAND-ALONE ELECTRODE HOLDER ........................................................................ 6
2.2 INSTALLING THE POWER ADAPTER.......................................................................................... 7
2.3 CONNECT THE PHELECTRODES ............................................................................................. 7
3. SETUP......................................................................................................................... 8
3.1 SET TEMPERATURE UNIT AND MTC VALUE .............................................................................. 8
3.2 SELECT A PREDEFINED BUFFER GROUP..................................................................................... 8
4. OPERATION ................................................................................................................ 9
4.1 CALIBRATION.................................................................................................................... 9
4.1.1 Buffer group .........................................................................................................9
4.1.2 Perform 1-point calibration................................................................................10
4.1.3 Perform 2-point calibration................................................................................11
4.1.4 Perform 3-point calibration................................................................................11
4.2 SAMPLE MEASUREMENT.................................................................................................... 12
4.2.1 pH measurement................................................................................................12
4.2.2 mV measurement...............................................................................................12
4.2.3 Temperature measurement ...............................................................................12
4.3 MEMORY ...................................................................................................................... 13
4.3.1 Store a reading...................................................................................................13
4.3.2 Recall a memory.................................................................................................13
4.3.3 Clear a memory..................................................................................................13
5. MAINTENANCE ......................................................................................................... 14
5.1 ERROR MESSAGE ............................................................................................................. 14
5.2 METER MAINTENANCE...................................................................................................... 14
5.3 ELECTRODE MAINTENANCE ................................................................................................ 15
5.4 CLEANING...................................................................................................................... 15
5.5 SELF-DIAGNOSIS.............................................................................................................. 15
5.6 RECOVER FACTORY SETTINGS.............................................................................................. 15
6. TECHNICAL DATA...................................................................................................... 16
6.1 SPECIFICATIONS .............................................................................................................. 16
6.2 DIMENSIONS .................................................................................................................. 17
7. BUFFER GROUP......................................................................................................... 18
8. COMPLIANCE............................................................................................................ 19

EN-2 AB23PH Bench pH Meter
1. INTRODUCTION
This manual contains installation, operation and maintenance instructions for a-AB23PH
bench pH meter. Please read it completely before installation and operation.
1.1. Safety precautions
Definition of Signal Warnings and Symbols
Safety notes are marked with signal words and warning symbols. These show safety
issues and warnings. Ignoring the safety notes may lead to personal injury, damage to
the instrument, malfunctions and false results.
WARNING
For a hazardous situation with medium risk, possibly resulting in severe
injuries or death if not avoided.
CAUTION
For a hazardous situation with low risk, resulting in damage to the device
or the property or in loss of data, or minor or medium injuries if not
avoided.
ATTENTION
For important information about the product. May lead to equipment
damage if not avoided.
NOTE
For useful information about the product.
Warning Symbols
General
hazard
Explosion
hazard
Electrical shock
hazard
Safety Precautions
CAUTION: Read all safety warnings before installing, making connections, or
servicing this equipment. Failure to comply with these warnings could result
in personal injury and/or property damage. Retain all instructions for future
reference.
 Before connecting power, verify that the AC adapter’s input voltage range
and plug type are compatible with the local AC mains power supply.
 Do not position the equipment such that it is difficult to reach the power
connection.
 Make sure that the power cord does not pose a potential obstacle or
tripping hazard.
 The equipment is for indoor use only.
 Do not operate the equipment in wet, hazardous or unstable
environments.
 When using chemicals and solvents, comply with the instructions of the
chemical producer and the general lab safety rules.
 Do not allow liquids to enter the equipment.
 Disconnect the equipment from the power supply when cleaning.
 Service should only be performed by authorized personnel.

AB23PH Bench pH Meter EN-3
WARNING: When using chemicals and solvents, comply with the instructions
of the producer and the general lab safety rules.
WARNING: Never work in an environment subject to explosion hazards! The
housing of the instrument is not gas tight. (Explosion hazard due to spark
formation, corrosion caused by the ingress of gases)
WARNING: Electrical shock hazards exist within the housing. The housing
should only be opened by authorized and qualified personnel. Remove all
power connections to the unit before opening.
1.2. Intended use
This instrument is intended for use in laboratories, pharmacies, schools, businesses and
light industry. It must only be used for measuring the parameters described in these
operating instructions. Any other type of use and operation beyond the limits of technical
specifications, without written consent from OHAUS, is considered as not intended. This
instrument complies with current industry standards and the recognized safety
regulations; however, it can constitute a hazard in use. If the instrument is not used
according to these operating instructions, the intended protection provided by the
instrument may be impaired.

EN-4 AB23PH Bench pH Meter
1.3. Display and Controls
Figure 1-1 Display
1. Electrode condition
Slope: more than 95%
and offset: ± (0-15) mV.
Slope: 90-95%
or offset: ± (15-35) mV.
Slope: less than 90%
or offset: ± (35-60) mV.
Electrode condition is
good.
Electrode condition is
acceptable.
Electrode condition is not
good or needs cleaning.
2. Calibration icon: blinks when calibration is in progress.
3. Measurement icon: blinks when measurement or calibration is in progress.
4. Auto endpoint icon ; Continuous reading icon .
5. Setup icon: shows when the meter is in setup mode.
6. Buffer icon: displays the buffer group for calibration.
7. Auto temperature compensation icon ATC; Manual temperature compensation
icon MTC.
Note: for detailed information about ATC and MTC, please check the Set
temperature unit and MTC value section in SETUP chapter.
8. Memory number icon MR; Error index icon Err;Store icon .
1
2
3
4
5
6
7
8

AB23PH Bench pH Meter EN-5
Controls
Figure 1-2 Control Panel
Button
Press & release
Press & hold
for 3 seconds
Exit
 Turns on the meter
 Cancels the current measurement
 Exits calibration
Turns off the meter
Store
Recall
 Stores the current measurement result
 When checking the stored
measurement results, moves to the
previous record.
 When setting parameters, increases
the setting value or displays the
previous option.
Recalls stored
measurement results
pH/mV
Switches between pH and mV mode.
/
Read/Enter
Auto - Stop
 Starts or ends measurement
 Ends the current measurement in the
auto endpoint mode and shows the
result
 Confirms settings and stores setting
parameters
Switches between
auto and continuous
endpoint mode
Auto
Continuous
Buffer
Temp.
 Selects buffer group
 When checking the stored
measurement results, moves to the
next record.
 When setting parameters, decreases
the setting value or displays the next
option.
Enters temperature
setting, selects
temperature unit and
sets MTC
temperature (The
default is 25.0 C°
degrees)
Cal
Cal.Data
Starts calibration
Recalls the latest
calibration data:
slope and offset

EN-6 AB23PH Bench pH Meter
2. INSTALLATION
2.1 Install the stand-alone electrode holder
1. Screw the metal rod into the base.
2. Hold the button located at the bottom of the upper electrode arm, and pass the
arm through the metal rod.
3. Release the button at the height you want to finish the installation.

AB23PH Bench pH Meter EN-7
2.2 Installing the power adapter
Insert the proper adapter clip into the power adapter slot.
2.3 Connect the pH electrodes
There are 3 sockets for electrode. “pH/mV” socket (BNC); “Temp.” Socket (Cinch) and
“Ref.” Socket (2mm banana).
For 2-in-1 pH electrode, you only need to connect to the BNC socket, while for other
electrodes, you need to connect to the BNC and Cinch socket.
Note: REF socket is for separate reference electrode.
pH/mV
V
Temp
Ref.
DC

EN-8 AB23PH Bench pH Meter
3. SETUP
3.1 Set temperature unit and MTC value
Please note:
If a temperature electrode is used, Automatic Temperature Compensation (ATC) and
the sample temperature are displayed on the screen. You may then choose to skip MTC
setup (below).
If the meter does not detect a temperature electrode or one is not used, the meter
automatically switches to Manual Temperature Compensation (MTC) mode and MTC
appears on the screen.
MTC temperature can be set as follows:
1. Press the Exit button to turn the meter on.
2. Long press the Temp. button to enter setting.
3. The symbol °C is flashing.
4. Press the or button to switch between °C and °F.
5. Press the Read/Enter button to confirm your selection.
6. Continue to set the MTC temperature by using or to adjust temperature
compensation accordingly
7. Press the Read/Enter button to confirm the setting.
8. Press the Exit button to return to the measurement screen.
Note:
1. The default MTC temperature value is 25°C (77°F).
2. °C = 5/9 (°F - 32).
3.2 Select a predefined buffer group
After confirming the MTC compensation temperature value, select the buffer group.
To do this:
1. Press the Buffer button to enter the selection.
2. Press the or
3. button to switch between 2 buffer groups.
4. Press the Read/Enter button to confirm the setting or press the Exit button to
return to the measurement screen.
The meter will then display the selected buffer
group on the right of the screen.
Check figure 3-1 as an example.
Figure 3-1 Buffer group

AB23PH Bench pH Meter EN-9
4. OPERATION
Standard procedure of pH measurement is as follows:
a) pH electrode preparation
b) Buffer preparation and pH electrode calibration
c) Sample preparation
d) pH measurement
e) Record measurement results or print
f) Rinse the pH electrode and properly store
pH electrode preparation: pH electrode should be rinsed with pure water before and
after using. Check if the electrode is physically damaged. (Be careful with the glass
bulb.)
The pH electrode should be stored in the storage bottle; the solution in the bottle is 3M
KCl solution. After placing the pH electrode into the sample or buffer solution, user
should stir several seconds then wait 30 to 60 seconds for the signal to stabilize, and
then press the button to operate (Calibration or measurement).
WARNING Do not operate the equipment in hazardous environments. The
equipment is not explosion protected.
WARNING When using chemicals and solvents, comply with the instructions
of the chemical producer and the general lab safety rules.
4.1 Calibration
4.1.1 Buffer group
This meter supports 1-, 2- or 3- point calibrations.
There are2 buffer groups in the meter, you can select the buffer group you prefer. The
default buffer is b1 US standards. The buffer value will be automatically recognized
during calibration. The 2 predefined buffer groups are (at 25°C):
The meter automatically corrects for the temperature dependence of the buffer pH
values given in the following table - buffer group b1.
This means, if the buffer solutions’ temperature is 15°C, the calibration value you will get
should be pH1.67 (buffer 1.68), pH4.00 (buffer 4.01), pH7.04 (buffer 7.00), pH10.12
(buffer 10.01) and pH12.81 （buffer 12.45）.
b1
1.68
4.01
7.00
10.01
12.45
b2
1.68
4.01
6.86
9.18
12.45

EN-10 AB23PH Bench pH Meter
Calibration: pH electrodes need to be calibrated with pH standard buffer solution before
a proper pH measurement can be made. Calibration is to display the right pH value
when meter receives the mV value signal from the pH electrode.
Slope: the linear coefficient between mV and pH according to theoretical value (e.g. -
59.16mV/pH @ 25 °C which means 100% slope);
Offset: the mV value when pH value is 7.00. (Theoretical value is 0 mV);
4.1.2 Perform 1-point calibration
When performing calibration, Ohaus recommends using Auto End Point Mode. After
powering the meter on, be sure the top of the screen shows to ensure the meter
is in Auto End point Mode.
4.1.2.1 Auto or Continuous End Point Mode
 Press and hold the Auto-Stop button to change the End Point Mode.
 When in Continuous Mode, to manually reach a pH measurement or calibration
value, you need to press the button Auto-Stop when reading is stable and
displays . Then the reading freezes and blinks 2 times then disappears;
blinks 3 times and freezes on the display.
 When in Auto End Point Mode, the meter determines when the reading is stable
then displays and locks the reading or calibration value automatically, the reading
freezes and blinks 2 times then disappears; blinks 3 times and freezes
on the display.
Note: For the 1-point calibration, if only the offset is adjusted, theoretical 100% slope (-
59.16 mV / pH) will be used.
5 °C
1.67
4.01
7.09
10.25
13.21
10 °C
1.67
4.00
7.06
10.18
13.00
15 °C
1.67
4.00
7.04
10.12
12.81
20 °C
1.68
4.00
7.02
10.06
12.63
25 °C
1.68
4.01
7.00
10.01
12.45
30 °C
1.68
4.01
6.99
9.97
12.29
35 °C
1.69
4.02
6.98
9.93
12.13
40 °C
1.69
4.03
6.97
9.89
11.98
45 °C
1.70
4.05
6.97
9.86
11.84
50 °C
1.71
4.06
6.96
9.83
11.70

AB23PH Bench pH Meter EN-11
4.1.2.2 1-point calibration
When the meter is in pH measurement mode, place the pH electrode in a calibration
buffer, stir 5 seconds, and wait for 30 seconds, then:
1 Press the Cal button. and appear on the top of the screen, and both are
blinking during calibration.
Note:
a) Calibration starts with the Auto End Point Mode.
b) Pressing the Auto-Stop button during the calibration can end the process.
2 The meter reaches endpoint automatically according to the preselected auto-
endpoint mode. The screen will display the calibration point pH value (e.g. 7.00)
with the temperature. The calibrated buffer value in the buffer group will be marked
in .
The 1-point calibration is finished. There are now 3 options (OHAUS recommends
conducting at least a 2 point calibration).
1. Press the Cal button to perform the 2-point calibration.
2. Press the Store button to store the 1-point calibration and exit, the offset and the
slope are shown on the display for 3 seconds then return to the measurement
screen.
3. Press the Exit button to reject the calibration, return to the measurement screen.
4.1.3 Perform 2-point calibration
After finishing the 1-point calibration as described above:
1 Rinse the pH electrode with pure water and wipe off with tissue.
2 Place the electrode in the next calibration buffer, stir and wait for 30 seconds.
3 Press the Cal button. and appear on the top of the screen, and both are
blinking during calibration.
Note:
a) Calibration starts with the Auto End Point Mode.
b) Pressing the Auto-Stop button during the calibration can end the process.
4 The meter reaches endpoint automatically according to the preselected auto-
endpoint mode. The screen will display the calibration point pH value (e.g. 7.00)
with the temperature. The second calibrated buffer value in the buffer group will be
marked in .
You have the same options after the 2-point calibration as the 1-point calibration. Please
check 1-point calibration section for details.
4.1.4 Perform 3-point calibration
Repeat the steps for performing a 2-point calibration to perform a 3-point calibration
using a third buffer.

EN-12 AB23PH Bench pH Meter
After all the calibrations are finished, the meter will display electrode condition ( , ,
, slope and offset) for 3 seconds, and then return to the measurement screen.
4.2 Sample measurement
4.2.1 pH measurement
1 Place the pH electrode in the sample. Stir for 5 seconds; wait for 30 seconds.
2 Press the Read/Enter button to start the pH measurement, appears on the
display and is blinking during measurement.
3 When the meter reaches endpoint ( blinks 2 times then disappears;
blinks 3 times and freezes on the display.), it will display the pH value and the
temperature.
Note: in Continuous End Point Mode, you need to press the Auto-Stop button to
manually end the measurement.
4.2.2 mV measurement
1 Press the pH/mV button to switch between pH measurement mode and mV
measurement mode.
2 Follow the same procedure as for pH measurement to perform mV measurement.
4.2.3 Temperature measurement
For better accuracy, we recommend to use either a built-in or a separate temperature
electrode.
 If a temperature electrode is used, ATC and the sample temperature are
displayed.
 If the meter does not detect a temperature electrode, it automatically switches to
the manual temperature compensation mode and MTC appears. MTC temperature
should be set.
Note: the meter accepts NTC 30 kΩ temperature sensor. ATC (Auto Temperature
Compensation) or MTC (Manual Temperature Compensation), the Temperature
Compensation only corrects for the change in the output of the electrode, not for the
change in the actual solution. This means the meter corrects the signal (mV) from the
electrode to get a more accurate pH value according to the real temperature.

AB23PH Bench pH Meter EN-13
4.3 Memory
4.3.1 Store a reading
The meter can store up to 99 endpoint results and 1 calibration result.
Press the Store button when the measurement reaches endpoint. flashes 3 times
and after that the measurement result has been stored.
If you press the Store button when M99 is displayed, FUL displays to indicate the
memory is full. To store further data you will have to clear the memory. (See the
following Clear the memory section for details).
4.3.2 Recall a memory
1. Press and hold the Recall button to recall the stored values from memory when
the current measurement reaches endpoint.
2. Press the or button to scroll through the stored results. R01 to R99
indicates which result is being displayed.
3. Press the Exit button to exit.
4.3.3 Clear a memory
1. Press the or button to scroll through the stored results until “CL” appears.
2. Press the Read/Enter button. CLr appears and blinks.
3. There are now 2 options:
 Press the Read/Enter button to confirm the deletion of all the stored data.
 Press the Exit button to return to the measurement mode without deleting the
memory.

EN-14 AB23PH Bench pH Meter
5. MAINTENANCE
5.1 Error message
Error Code
Possible Cause
Possible Solution
Error 1
Self-diagnosis failed
Repeat the self-diagnosis procedure
and make sure that you finish pressing
all six buttons within two minutes.
Error 2
Measured values out of
range
Check if the electrode is properly
connected and placed in the sample
solution.
Error 3
Measured buffer
temperature out of range
(<0 °C or >50 °C)
Keep the pH buffer temperature within
the range for calibration
Error 4
Offset out of range
offset > 60mV or < - 60 mV
Make sure the pH buffer is correct and
fresh; Clean or replace the pH
electrode.
Error 5
Slope out of range
Make sure the buffer is correct and
fresh; Clean or replace the pH
electrode.
Error 6
Meter cannot recognize the
buffer
Make sure the buffer is correct and
fresh; check if the buffer has not been
used more than once.
Error 9
The current data set has
already been stored once
An endpoint reading can only be stored
once. Perform a new measurement to
store.
Error 10
The sample temperature
out of range
Check the sample temperature, the
temperature sensor.
Note: If an error happens, the meter will also beep 3 times to alert.
If the troubleshooting section does not resolve your problem, contact an OHAUS technical
support agent. For assistance in the United States, call toll-free 1-800-526-0659 between
8:00 AM and 5:00 PM Eastern Standard Time. An OHAUS Technical Support Specialist
will be available to assist you. Outside the USA, please visit our website www.ohaus.com
to locate the OHAUS office nearest you.
5.2 Meter maintenance
Never unscrew the two halves of the housing!
The meter does not require any maintenance other than occasional wipe with a damp
cloth and the replacement of depleted batteries.
The housing is made of acrylonitrile butadiene styrene (ABS). This material is attacked
by some organic solvents, such as toluene, xylene and methyl ethyl ketone (MEK). Any
spillage should be immediately wiped off.

AB23PH Bench pH Meter EN-15
5.3 Electrode maintenance
Make sure the electrode is filled with electrolyte solution. Always store the electrode
according to the electrode instruction manuals and do not allow it to dry out.
If the electrode response becomes sluggish or the slope is not acceptable, try the
following:
 Soak the electrode in 0.1M HCl for at least 8 hours.
 For fat or oil contaminant, degrease the membrane with cotton wool soaked in
either acetone or a soap solution.
After electrode treatment, a new calibration should be performed. If the electrode slope
is still not acceptable, the electrode might need to be replaced.
5.4 Cleaning
The housing may be cleaned with a cloth dampened with a mild detergent if necessary.
5.5 Self-diagnosis
When the meter is on, press and hold the Read/Enter button and the Cal button
simultaneously until the meter displays the full screen. Each icon blinks one after the
other.
This way you may check whether all icons are correctly shown. The next step is to
check that the buttons are functioning correctly. This requires user interaction.
When b blinks, six icons (including b) are displayed.
Press the six buttons in any order. Each time you press a button, an icon disappears
from the screen. Continue to press the other buttons until all the icons have
disappeared.
When the self-diagnosis has been completed successfully, PAS appears. If self-
diagnosis fails, error message Err 1 appears.
Note: You have to finish pressing all six buttons within 2 minutes, otherwise Err 1
appears and you will have to repeat the procedure.
5.6 Recover factory settings
When the meter is off, press and hold the Read/Enter button, Cal button and Exit
button together for 3 seconds, the screen displays and blinks, this means
“Reset”. There are 2 options:
 Press the Read/Enter button to reset factory settings (MTC, slope and offset, etc.),
display then restart the meter.
WARNING: Electric Shock Hazard. Disconnect the equipment from
the power supply before cleaning.
Make sure that no liquid enters the interior of the instrument.
Attention: Do not use solvents, harsh chemicals, ammonia or
abrasive cleaning agents.

EN-16 AB23PH Bench pH Meter
 Or press the Exit button to quit the setting, display then turn off the meter.
6. TECHNICAL DATA
6.1 Specifications
Equipment Ratings:
Indoor use only
Altitude:
2000m
Operating temperature:
5 to 40°C
Humidity:
Maximum relative humidity 80% for temperatures up to
31 °C decreasing linearly to 50% relative humidity at 40°C.
Electrical supply:
12VDC, 0.1A. (For use with certified or approved power supply,
which must have a SELV and limited energy output.)
Voltage fluctuations:
Mains supply voltage fluctuations up to ±10% of the
nominal voltage.
Overvoltage category
(Installation category):
II
Pollution degree:
2
Benchtop Meter Model
a-AB23PH
Display Type
5" segment LCD with backlight
Measurement Channels
1
Measurement End-point
Modes
Auto-stop, Continuous
Datalog for Measurement
99 sets
Datalog for Calibration
Last calibration
Keypad
Membrane
pH Electrode Input
BNC
Temperature Input
Cinch, NTC 30 kΩ
Power Supply
Power input: 100-240V~ 200mA 50-60Hz 12-18VA
Power output: 12 VDC 0.5A
Net Weight
2.5 kg
Gross Weight
2.8 kg
Transportation Size
370 x 268 x 251 mm

AB23PH Bench pH Meter EN-17
pH Meter Model
a-AB23PH
Measurement Channels
pH/mV with temperature
PH
Measuring Range
0.00 to 14.00 pH
Resolution
0.01 pH
Resolution Switch
No
Accuracy
± 0.01 pH
Pre-Defined Buffer
Groups
2
ORP, RmV
Measuring Range
± 1999 mV
Resolution
1 mV
Accuracy
± 1 mV
Units
mV
Temperature
Measuring Range
0.0 to 100.0 °C,
32.0 °F to 212.0 °F
Resolution
0.1 °C, 0.1 °F
Accuracy
± 0.5 °C, ±0.5 °F
Calibration
No
Calibration
Calibration points
Up to 3 points
Calibration Sign
Face Sign
Calibration mode
Linear
6.2 Dimensions
Figure 6-1 Dimensions
210 mm
142 mm
51 mm

EN-18 AB23PH Bench pH Meter
7. BUFFER GROUP
The meter automatically correct for the temperature dependence of the buffer group pH
value given in the following tables.
Buffer group 1
Temp °C pH1.68 pH4.01 pH7.00 pH10.01 pH12.45
5 1.67 4.01 7.09 10.25 13.21
10 1.67 4.00 7.06 10.18 13.00
15 1.67 4.00 7.04 10.12 12.81
20 1.68 4.00 7.02 10.06 12.63
25 1.68 4.01 7.00 10.01 12.45
30 1.68 4.01 6.99 9.97 12.29
35 1.69 4.02 6.98 9.93 12.13
40 1.69 4.03 6.97 9.89 11.98
45 1.70 4.05 6.97 9.86 11.84
50 1.71 4.06 6.96 9.83 11.70
Buffer group 2
Temp °C pH1.68 pH4.01 pH6.86 pH9.18 pH12.45
5 1.67 4.01 6.95 9.39 13.21
10 1.67 4.00 6.92 9.33 13.00
15 1.67 4.00 6.90 9.28 12.81
20 1.68 4.00 6.88 9.23 12.63
25 1.68 4.01 6.86 9.18 12.45
30 1.68 4.01 6.85 9.14 12.29
35 1.69 4.02 6.84 9.11 12.13
40 1.69 4.03 6.84 9.07 11.98
45 1.70 4.04 6.83 9.04 11.84
50 1.71 4.06 6.83 9.02 11.70