Apera Instruments 9500 Premium Series User manual

9500 Premium Series
Benchtop pH/Conductivity Meter
User Manual
PH9500 Benchtop pH Meter
EC9500 Benchtop Conductivity Meter
PC9500 Benchtop pH/Conductivity Meter
APERA INSTRUMENTS, LLC
aperainst.com

1Introduction...............................................................................................................................................................- 1 -
1.1 Parameters .....................................................................................................................................- 1 -
1.2 Basic Features and Functions ........................................................................................................- 1 -
1.3 Features of pH Measurement.........................................................................................................- 1 -
1.4 Features of Conductivity Measurement..........................................................................................- 2 -
2Technical Specifications ......................................................................................................................................... - 2 -
2.1 Technical Parameters .....................................................................................................................- 2 -
2.2 Others .............................................................................................................................................- 3 -
3Meter Illustration .....................................................................................................................................................- 3 -
3.1 Main Interface.................................................................................................................................- 3 -
3.2 Measurement Interfaces.................................................................................................................- 4 -
3.3 Keypad ...........................................................................................................................................- 6 -
3.3.1 Keypad Operation........................................................................................................................................................ - 6 -
3.3.2 Function........................................................................................................................................................................... - 7 -
3.3.3 Manual temperature compensation......................................................................................................................- 7 -
3.4 Meter Sockets.................................................................................................................................- 8 -
3.5 Reading Mode ................................................................................................................................- 9 -
3.6 Meter Installment ..........................................................................................................................- 10 -
3.6.1 Connect Test-Bench..................................................................................................................................................- 10 -
3.6.2 Install flexible electrode holder .............................................................................................................................- 10 -
3.6.3 How to use Test-Bench............................................................................................................................................- 10 -
3.7 Magnetic Stirrer Operation ........................................................................................................... - 11 -
3.7.1 Technical Specifications ...........................................................................................................................................- 11 -
3.7.2 Operation......................................................................................................................................................................- 11 -
3.7.3 Notes ..............................................................................................................................................................................- 11 -
4Meter Setup.............................................................................................................................................................- 11 -
4.1 Setup before Use.......................................................................................................................... - 11 -
4.2 Screen Display Setup ................................................................................................................... - 11 -
4.3 Parameter Settings.......................................................................................................................- 12 -
4.3.1 Main Menu and Sub-menu....................................................................................................................................- 12 -
4.3.2 Operation......................................................................................................................................................................- 13 -
4.3.3 Parameter Settings Content ...................................................................................................................................- 13 -
4.4 Calibration Password....................................................................................................................- 14 -
5pH Measurement ...................................................................................................................................................- 14 -
5.1 About pH Calibration ....................................................................................................................- 14 -
5.1.1 Standard pH Calibration Buffer Solutions..........................................................................................................- 14 -

5.1.2 5-point Calibration ....................................................................................................................................................- 15 -
5.1.3 Calibration Frequency...............................................................................................................................................- 16 -
5.1.4 Check calibration record..........................................................................................................................................- 16 -
5.1.5 pH Calibration Reminder.........................................................................................................................................- 16 -
5.2 pH Meter Calibration.....................................................................................................................- 16 -
5.3 User-Define Calibration (take 2.00 pH and 7.30 pH as an example) ...........................................- 19 -
5.4 Self-Diagnosis ..............................................................................................................................- 20 -
5.5 Sample Measurement ..................................................................................................................- 21 -
5.6 About pH Measurement................................................................................................................- 22 -
5.6.1 pH Stability Criterion.................................................................................................................................................- 22 -
5.6.2 pH Reading Alarm......................................................................................................................................................- 22 -
5.6.3 pH Isothermal Measurement Principal ...............................................................................................................- 23 -
5.6.4 Back to Factory Default Settings ...........................................................................................................................- 23 -
5.7 pH Electrode Maintenance ...........................................................................................................- 23 -
5.7.1 Daily Maintenance .....................................................................................................................................................- 23 -
5.7.2 Calibration Solutions.................................................................................................................................................- 24 -
5.7.3 Cleaning.........................................................................................................................................................................- 24 -
6mV Measurement...................................................................................................................................................- 24 -
6.1 ORP Measurement .......................................................................................................................- 24 -
6.2 ORP Measurement Notes ............................................................................................................- 24 -
6.3 ISE Measurement.........................................................................................................................- 25 -
7Conductivity Measurement .................................................................................................................................- 25 -
7.1 Conductivity Electrode Information...............................................................................................- 25 -
7.1.1 Default Electrode........................................................................................................................................................- 25 -
7.1.2 Conductivity Cell Constant......................................................................................................................................- 25 -
7.2 Conductivity Calibration Information.............................................................................................- 25 -
7.2.1 Conductivity Standard Calibration Solutions....................................................................................................- 25 -
7.2.2 Calibration Frequency...............................................................................................................................................- 26 -
7.2.3 Check Calibration Record........................................................................................................................................- 26 -
7.2.4 Conductivity Calibration Reminder ......................................................................................................................- 26 -
7.2.5 Reference Temperature ...........................................................................................................................................- 26 -
7.2.6 Temperature Compensation Coefficient............................................................................................................- 27 -
7.2.7 Prevent Contamination of Standard Solutions ................................................................................................- 27 -
7.3 Conductivity Meter Calibration (Take 1413μS/cm as an example) ..............................................- 28 -
7.4 User-Define Calibration (Take 10μS/cm as an example) .............................................................- 29 -
7.5 Self-Diagnosis ..............................................................................................................................- 30 -
7.6 Sample Measurement ..................................................................................................................- 31 -
7.7 TDS and Conductivity...................................................................................................................- 31 -

7.8Salinity Types ...............................................................................................................................- 32 -
7.9 Back to Factory Default Settings ..................................................................................................- 32 -
7.10 Conductivity Electrode Maintenance ............................................................................................- 32 -
8Data Processing Modes (Save, Recall, Print, Delete) ....................................................................................- 33 -
8.1 Data Processing Flowchart ..........................................................................................................- 33 -
8.2 Log Data in Meter .........................................................................................................................- 34 -
8.2.1 Setup...............................................................................................................................................................................- 34 -
8.2.2 Data Storage................................................................................................................................................................- 34 -
8.2.3 Data Logging Modes ................................................................................................................................................- 34 -
8.2.4 Save, Recall, Delete....................................................................................................................................................- 34 -
8.3Print Data......................................................................................................................................- 35 -
8.3.1 Setup...............................................................................................................................................................................- 35 -
8.3.2 Install Printer ................................................................................................................................................................- 35 -
8.3.3 Printer Information ....................................................................................................................................................- 36 -
8.3.4 Data logging and printing.......................................................................................................................................- 36 -
8.3.5 Delete Data...................................................................................................................................................................- 36 -
8.4 Data logging via PC......................................................................................................................- 37 -
8.4.1 Install Software............................................................................................................................................................- 37 -
8.4.2 Software Interface ......................................................................................................................................................- 37 -
8.4.3 Operation Keys of PC-Link .....................................................................................................................................- 38 -
9What’s in the Kit.....................................................................................................................................................- 38 -
10 Other Parts and Accessories ...........................................................................................................................- 39 -
11 Warranty ..............................................................................................................................................................- 40 -
Notes
•When the meter is connected to PC, do not pull out the USB cable until
the meter is turned off. Otherwise a system crash could occur. To fix the
crash, pull out the power cord, put it back in, and reboot the meter.
•Please do NOT pull out the power cord when the meter is turned on.

- 1 -
1 Introduction
Thank you for choosing Apera 9500 Premium Series Benchtop pH/Conductivity Meter. Before using this
product, please read this manual carefully.
9500 Series Benchtop Meter is an outstanding combination of advanced electronic technology, sensor
technology and intuitive software design, made for laboratory pH and conductivity measurement in
scientific research and quality control, fully meeting GLP (Good Laboratory Practice) standards.
1.1 Parameters
Measurement parameter
PH9500
EC9500
PC9500
pH/mV
√
√
Cond./TDS/Salinity/Resistivity
√
√
Temperature
√
√
√
1.2 Basic Features and Functions
•Large TFT color display with a user-friendly navigation system.
•Self-diagnosis function reminds users of electrode invalidity, incorrect calibration solutions, or
incorrect operation.
•Fully meets GLP (Good Laboratory Practice) Standard. Users can attach a keyboard to set up
calibration password, sample ID, electrode ID, user ID, and company name.
•Users can attach a printer (sold separately) to print out data meeting GLP/GMP standard.
• button to check on the built-in instructions of the meter
•Multi-language operation system, including English, German, Spanish, and Chinese.
•Equipped with a multi-functional Test-Bench, composed of a flexible electrode holder, buffer
organizers, and an intelligent magnetic stirrer.
•A variety of measurement modes for different requirements, including stable display mode, auto. hold
mode, auto. data logging mode, and dial mode
•USB data output for printing and further analysis, auto. data logging in the 9500 PC-Link desktop
software.
•PC9500 meter can measure and display pH & conductivity value at same time.
1.3 Features of pH Measurement
•1 to 5 points of automatic calibration with calibration instruction and automatic checking functions.
•Automatically recognize pH buffer solution. 3 series buffer solution selectable: USA series, NIST
series and CH series, as well as User-Define solutions (any pH standard solutions).
•pH high/low value alarm function

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1.4 Features of Conductivity Measurement
•1 to 4 points of automatic calibration with calibration instruction and automatic checking functions.
•Automatically recognize conductivity standard solutions. 2 series standard solution available:
Standard Series and CH Series, as well as User-Define solution (any conductivity standard solutions).
•Measurement modes include conductivity, TDS, salinity, and resistivity.
2 Technical Specifications
2.1 Technical Parameters
Technical Parameters
Applicable
Models
pH
Range
-2.000 to 20.000 pH
PH9500
PC9500
Resolution
0.1/0.01 /0.001pH
Accuracy
±0.002 pH ±1 digit
Temp. Compensation Range
0 to 100°C (auto. or manual)
Calibration Points
1 to 5 points
Buffer Series Options
USA, NIST, CH, and User-Define
mV
Range
±2000.0mV
Resolution
0.1mV
Accuracy
±0.03% F.S ±1 digit
Conductivity
Range
0.00 μS/cm to 2000 mS/cm
EC9500
PC9500
Resolution
0.01/0.1/1μS/cm; 0.01/0.1/1 mS/cm
Accuracy
±0.5% F.S ±1 digit
Temp. Compensation Range
0 to 50°C (auto. or manual)
Cell Constant
0.1/1/10 cm-1
Reference Temp.
15 to 30°C (adjustable)
Temp. Compensation
Coefficient
0.00 to 10.00% (adjustable)
Calibration Points
1 to 4 points
Standard Series Options
Standard, CH, User-Define
TDS
Range
0.00 mg/L to 1000 g/L
EC9500
PC9500
Resolution
0.01/0.1/1mg/L; 0.01/0.1/1 g/L
Accuracy
±1.0% F.S ±1 digit
Temp. Compensation Range
0 to 50°C (auto. or manual)
TDS Factor
0.40 to 1.00 (adjustable)

- 3 -
Salinity
Range
0.00 to 100 ppt
EC9500
PC9500
Resolution
0.01/0.1 ppt
Accuracy
±1.0% F.S ±1 digit
Temp. Compensation Range
0 to 50°C (auto. or manual)
Salinity Type
Linear / NaCl / Saltwater
Resistivity
Range
0.00 Ω·cm to 100MΩ·cm
EC9500
PC9500
Resolution
0.1/1 Ω·cm; 0.01/0.1/1KΩ·cm; 0.1
MΩ·cm
Accuracy
±1.0% F.S ±1 digit
Temp. Compensation Range
0 to 50°C (auto. or manual)
Temperature
Range
-10.0 to 110.0°C; 14.0 to 230°F
PH9500
EC9500
PC9500
Resolution
0.1°C; 0.1/1°F
Accuracy
±0.5°C±1 digit
2.2 Others
Data Storage
PH9500/EC9500: 1000 groups; PC9500: 2000 groups
Power Supply
DC9V/600mA
Dimensions and Weight
Meter: (360×235×100) mm / 1.7kg
3 Meter Illustration
3.1 Main Interface
Diagram-1 is the complete pH measurement interface.
Diagram-1

- 4 -
①
Measurement Mode
⑪
Measurement Unit
②
pH Measurement
⑫
Auto. Hold
③
mV value of pH electrode
⑬
Stable reading
④
Electrode ID
⑭
Date and time
⑤
Completed calibration(s)
⑮
⑥
Sample ID
⑯
⑦
User ID
⑰
Printer
⑧
Used data storage
⑱
⑨
Temperature value and unit (°C°F)
⑲
Calibration reminder
⑩
Temperature compensation: ATC –
Automatic Temperature Compensation;
MTC – Manual Temperature
Compensation
⑳
Alarms of readings exceeding min/max
values
3.2 Measurement Interfaces
pH Measurement Interface
applicable models: PH9500/PC9500
①-- pH measurement mode
②-- pH measurement
③-- mV value of pH electrode
④-- completed pH calibration(s)
⑤-- Temperature measurement
⑥-- Stable reading
⑦-- Date and time
mV (ORP) Measurement Interface
applicable models: PH9500/PC9500
①-- mV measurement mode
②-- mV measurement
③-- Temperature measurement
④-- stable reading
⑤-- Date and time
PC
Manual data log
Current stirring
speed
Saved stirring
speed
Auto. data log
Meter memory

- 5 -
Conductivity Measurement Interface
applicable models: EC9500/PC9500
①-- Conductivity measurement mode
②-- Conductivity measurement
③-- Conductivity parameters (see section 7.1.2,
7.2.5, 7.2.6)
④-- Completed conductivity calibration(s)
⑤-- Temperature measurement
⑥-- Stable reading
⑦-- Date and time
TDS Measurement Interface
applicable models: EC9500/PC9500
①-- TDS measurement mode
②-- TDS measurement
③-- TDS conversion factor (see section 7.7）
④-- Temperature measurement
⑤-- Stable reading
⑥-- Date and time
Salinity Measurement Interface
applicable models: EC9500/PC9500
①-- Salinity measurement mode
②-- Salinity measurement
③-- Salinity type (see section 7.8）
④-- Temperature measurement
⑤-- Stable reading
⑥-- Date and time
Resistivity Measurement Interface
applicable models: EC9500/PC9500
①-- Resistivity measurement mode
②-- Resistivity measurement
③-- Temperature measurement
④-- Stable reading
⑤-- Date and time
pH/Conductivity Measurement Interface
applicable models: PC9500
①-- pH/conductivity measurement mode
②-- pH stable reading
③-- pH measurement
④-- Temperature for pH
⑤-- Completed pH calibration(s)
⑥-- Completed conductivity calibration(s)
⑦-- Temperature for conductivity
⑧-- Conductivity measurement
⑨-- Conductivity stable reading
⑩-- Date and time

- 6 -
3.3 Keypad
3.3.1 Keypad Operation
Short press – Press key and hold for less than 2 seconds, buzzer makes a beep;
Long press – Press key and hold for more than 2 seconds, buzzer makes a beep when short pressing
the button, another beep will ring after holding the key for 2 seconds.
Table-1 Keypad Operation and Functions
Key
Operation
Functions
Short
press
●Power on/off
Short
press
Press to switch among different measurement modes：
● PH9500:pH→mV
● EC9500: Conductivity→TDS→Salinity→Resistivity
● PC9500: pH→mV→Conductivity→TDS→Salinity→pH/conductivity
Long
press
●Enter manual temperature compensation
Long
press
●In measurement mode, press to enter calibration
Short
press
●End all current operations and go back to measurement mode
Diagram-2

- 7 -
Short
press
•In measurement mode: press to enter parameter set-up main menu;
•In calibration mode: press to perform calibration;
•In main menu: press to enter submenu;
•In submenu: press to enter parameter set-up;
•In parameter set-up mode: press to confirm parameter;
•In manual temperature compensation: press to confirm temperature
value.
Short
press
• In measurement mode: press key to store measurements,
• press key to recall saved data;
•In recall (RM) mode: press or key to turn pages;
•In menu mode: press key to select items;
•In manual temperature compensation: press to change temperature
value, hold the key for fast changing.
Short
press
•Check quick guide
Short
press
•Turn on/off magnetic stirrer
Long
press
•Save the current stirring speed
Short
press
•Switch between current speed and the saved speed
Short
press
•Press to change stirring speed. Hold the key to change speed quickly.
3.3.2 Function
Press key to check the quick user guide of the meter,
including keypad operation information, icon information,
calibration illustration, calibration notes, electrode
maintenance, parameter settings, etc. Diagram-3 is the
index of content, which is only in English or Simplified
Chinese.
3.3.3 Manual temperature compensation
When no temperature probe is connected to the meter, long press to enter manual temperature
compensation mode. Press or to adjust temperature value. Hold the key to quickly
change values. Short press to confirm and go back to measurement mode.

- 8 -
3.4 Meter Sockets
Table - 2 Meter Sockets Information
Socket Type
Information
①
BNC
Connect pH or ORP combination electrode
②
Ф2 power supply
Connect magnetic stirrer
③
RCA
Connect temperature sensor (for pH)
④
USB
Connect printer
⑤
USB
Connect PC
⑥
Ф4 banana
Connect reference electrode
⑦
BNC
Connect conductivity electrode
⑧
RCA
Connect temperature sensor (for conductivity)
⑨
USB
Connect keyboard
⑩
Ф2.5 power supply
Connect DC9V adaptor
Diagram-4

- 9 -
3.5 Reading Mode
3.5.1 Stable Reading Mode
When reading is stable, shows up. If you don’t see
the smiley face or it’s flashing, it means the reading is not
fully stabilized and it’s not the right timing to record or
calibrate.
3.5.2 Auto. Hold Mode
Choose “on” in parameter setting 4.6 to turn on Auto. Hold
mode. When stays on for more than 10 seconds, the
reading will be automatically locked, and HOLD icon will
show up. Short press to unlock.
3.5.3 pH dial display mode
Turn on the pH dial display mode in parameter setting 1.7.
This mode is featured with a vivid, stable, and continuous
display. The bottom right is the digital value.
3.5.4 Auto. timing mode
Setup auto. timing data logger in parameter settings 3.2 to
record measurements in long-term. When connected to
PC, a measurement curve can be formed in the PC-Link
software as shown right.
Note The icon will be displayed when the reading gets stabilized, but the measurement will continue.
When the measured value changes beyond a certain range, the icon will flash or disappear until it
stabilizes again. The stability of the reading is related to many factors:
•Measurement time -- the longer the measurement time, the more stable the icon will be;
•Nature of the test solution – the solution with low ionic strength (such as distilled or deionized water),
or the solution with unstable chemical nature, the measurement will not be easy to stabilize.
•The following three methods will help improve reading stability.
•(a) Turn on Auto. Hold Mode (parameter setting 4.6), refer to section 3.5.2.
•(b) Select the appropriate “pH stability standard” for different test solutions (parameter setting 1.5),
refer to section 5.6.1.
•(c) Select the right pH electrode for each specific application, see section 10.

- 10 -
3.6 Meter Installment
3.6.1 Connect Test-Bench
Before installment
After installment
3.6.2 Install flexible electrode holder
3.6.3 How to use Test-Bench
Meter
Stirrer cable
Connecting board
Diagram-5
Diagram-7
Test-Bench
(a) Use in a connected manner
(b) Use in a separated manner
Diagram-6
Align the hole and
bar, then press
down with force.

- 11 -
3.7 Magnetic Stirrer Operation
3.7.1 Technical Specifications
Speed Range
0 to 2300 RPM (no load)
Working area diameter
Ф100mm
Max. stirring volume
1000mL
3.7.2 Operation
(a) Insert the stirrer cable to the corresponding sockets in meter and stirrer.
(b) Short press to power on stirrer, will show up on the top of the display. Press or to
adjust stirring speed. Short press the key to adjust slowly; Hold the key to adjust quickly. Icon
indicates that the stirrer is powered on and it’s stirring at the current speed.
(c) How to use ：After stirring speed is adjusted, hold for about 3 seconds until the buzzer
makes a beep. The adjusted speed is now saved. Next time, if you want to use this saved speed,
just short press , and icon will show up on top.
(d) Switch between two speeds: After saved speed and current speed are adjusted, short press
again to alternate between the saved speed ( ) and the current speed ( )
3.7.3 Notes
•If the bottom surface of the beaker is not flat, it will vibrate or even stop stirring. In this case, replace
a more qualified beaker.
•At zero speed, do not hold button, otherwise zero speed will be stored. If this is the case, just
re-adjust the speed and store it by holding again.
4 Meter Setup
4.1 Setup before Use
Before first-time use, please check the following settings and make adjustments: temperature unit, date
format, date, time, system language, pH resolution, pH buffer series, conductivity standard series, etc.
For details, refer to section 4.3.
4.2 Screen Display Setup
In parameter settings 4.5, choose Simple or Complete display mode. Complete display mode includes
electrode ID, user ID, and sample ID as shown in Diagram-8 (b). For setting up ID, refer to section 8.3.3-
(c).
(b) Complete Display
Diagram-8
(a) Simple Display

- 12 -
4.3 Parameter Settings
4.3.1 Main Menu and Sub-menu
Diagram-9
pH sub-menu
Main Menu
Conductivity/TDS sub-menu
Data management Sub-menu
Settings Sub-menu

- 13 -
4.3.2 Operation
For detailed operation, please follow the instruction at the bottom of screen.
4.3.3 Parameter Settings Content
Main
Menu
#
Parameter
Settings Content
Default
Info
pH
1.1
pH buffer standard
USA/NIST/CH/User-Define
/
Refer to
section 5.1.1
1.2
Resolution
0.001/0.01/0.1
0.01
/
1.3
Calibration info
View/Print
Check
Refer to
section 5.1.4
1.4
Calibration reminder
Off/Hour/Day
Off
Refer to
section 5.1.5
1.5
Stability standard
Low/Medium/High
Medium
Refer to
section 5.6.1
1.6
Max/min reading
alarm
Off/Max/Min
Off
Refer to
section 5.6.2
1.7
Display mode
Digital/Dial
Digital
Refer to
section 3.5.3
1.8
Electrode ID
---------
/
Refer to
section 8.3.3-
(c)
1.9
Back to factory
default
No/Yes
No
Refer to
section 5.6.4
Cond./
TDS
2.1
Cell constant
10/1.0/0.1
1.0
Refer to
section 7.1.2
2.2
Calibration solution
standard
CH/Standard/User-Define
/
Refer to
section 7.2.1
2.3
Calibration info
Check/Print
Check
Refer to
section 7.2.3
2.4
Calibration reminder
Off/Hour/Day
Off
Refer to
section 7.2.4
2.5
Reference temp.
15 to 30°C
25°C
Refer to
section 7.2.5
2.6
Temp. compensation
coefficient
0.00 to 10.0%
2.00%
Refer to
section 7.2.6
2.7
TDS factor
0.40 to 1.00
0.71
Refer to
section 7.7
2.8
Salinity type
Linear/NaCl/Saltwater
Linear
Refer to
section 7.8
2.9
Electrode ID
---------
/
Refer to
section 8.3.3-
(c)
2.10
Back to factory
default
No/Yes
No
Refer to
section 7.6.4
Data
3.1
Logging data to
Memory/Printer/PC
/
Refer to section
8.2.1/8.3.1.
3.2
Logging mode
Manual/Auto.
/
Refer to
section 8.2.3
3.3
Printing format
Simple/Complete
/
Refer to section
8.3.3(a)to(b)
3.4
Delete data in
memory
Yes/No
/
Refer to
section 8.2.4-
(d)
Settings
4.1
Sample ID
---------
/
Refer to
section 8.3.3-
(c)

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4.2
User ID
---------
/
Refer to
section 3.3.3-
(c)
4.3
Company name
---------
/
Refer to
section 8.3.3-
(c)
4.4
Calibration password
---------
/
Refer to
section 4.4
4.5
Display info
Simple/Complete
/
Refer to
section 4.2
4.6
Auto. Hold
On-Off
/
Refer to
section 3.5.2
4.7
Temperature unit
°C - °F
/
/
4.8
Date format
YYYY-MM-DD/MM-DD-
YYYY/DD-MM-YYYY
/
/
4.9
Date setting
---
/
/
4.10
Time setting
---
/
/
4.11
Language
Chinese-English-German-
Spanish-French-Italian
/
/
4.4 Calibration Password
•The factory setting of the calibration password is “None” and the initial password is 000000. To set
the calibration password, connect the keyboard, enter parameter setting 4.4, press key, and
then enter the initial password twice as prompted;
•To set the new password, enter the old password first, then enter the new password twice. The
password is up to 8 English letters or numbers;
•Cancel password: Enter the old password in parameter setting 4.4 and press key to confirm,
then ignore the prompt to enter the new password, just press key twice to cancel password.
•There is a confidential envelope comes with the meter that has a set of “super password”. Please
make sure to properly save it. In case you have forgotten your password, you can use this super
password to unlock it, or contact your supplier.
5 pH Measurement
5.1 About pH Calibration
5.1.1 Standard pH Calibration Buffer Solutions
The meter has 3 series of standard pH buffers: USA, NIST, and CH; plus user-define buffers. Users can
make the selection in parameter setting 1.1 (buffer solution standard). The 3 standard series are as shown
in Table-3. For User-define buffers, refer to section 5.3.

- 15 -
Table-3 pH Standard Buffer Series
Calibration Icon
pH Standard Buffer Series
USA
NIST
CH
5-point
Calibration
1.679 pH
1.680 pH
1.680 pH
4.005 pH
4.003 pH
4.003 pH
7.000 pH
6.864 pH
6.864 pH
10.012 pH
9.182 pH
9.182 pH
12.454 pH
12.454 pH
12.460 pH
Note: the calibration icons are examples of USA standard series. In practice, these icons will change
according to the series selected by users.
5.1.2 5-point Calibration
Users can choose 1 to 5 points of calibration. The 1st point of calibration must be 7.00 pH (or 6.86 pH in
NIST and CH Series). Then choose other buffers to calibrate 2nd point to 5th point. There are a variety
of combos of calibration points. The most commonly used combos are the 3-point one: 4.00 pH, 7.00 pH,
10.01 pH, and the combos that are suitable for strong acid/alkaline samples as shown in Table-4.
Generally, make sure the estimated pH range of your sample solutions falls in the two points of calibration.
Table-4 Commonly Used Calibration Combo (Take USA Series as an example)
USA Series
Calibration Icons
Applicable
Scenarios
1-pt calibration
7.00pH
accuracy≥±0.1pH
2-pt calibration
7.00pH and 4.00pH
<7.00 pH
7.00pH and 10.01pH
>7.00 pH
7.00pH and 1.68pH
Strong acid
samples
7.00pH and 12.45pH
Strong alkaline
samples
3-pt calibration
7.00pH, 4.00pH, and 10.01pH
0 to 14.00pH

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5.1.3 Calibration Frequency
The frequency that you need to calibrate your meter depends on the tested samples, condition of
electrodes, and the requirement of the accuracy. For High-Accuracy measurement (≤ ±0.02pH), the meter
should be calibrated before test every time; For general-accuracy measurements (≥±0.1pH), once
calibrated, the meter can be used for about a week or longer. In the following cases, the meter must be
re-calibrated before next use:
a) The electrode hasn’t been used for a long time or a new electrode is connected.
b) After measuring strong acid (pH<2) or strong alkaline (pH>12) solutions.
c) After measuring fluoride-containing solution and strong organic solution.
d) There is a significant temperature difference between the test sample and the buffer solution.
5.1.4 Check calibration record
In parameter setting 1.3 (Calibration info), users can choose
to view or print. When choosing “view”, press to
display the last calibration record as shown in Diagram-10.
When choosing “print”, press to print out the last
calibration data (the meter’s data logging mode must be in
printer mode, and the printer’s status must be online. Refer
to section 8.3.4 for details).
5.1.5 pH Calibration Reminder
Users can set up pH calibration reminder in parameter
setting 1.4. When time is due, the red reminder icon will
show up as shown in Diagram-11. This will not affect the
normal operation of the meter. After calibration or choosing
none in parameter setting 1.4, the reminder icon will
disappear.
5.2 pH Meter Calibration
The following calibration process takes 4.00 pH, 7.00 pH, and 10.01 pH as an example. Put LabSen 211
pH Combination Electrode and MP500 temperature electrode on the flexible electrode holder and connect
to the meter.
Note: the electrode mentioned in Table-5 and Table-6 refers to pH combination electrode and temperature
electrode.
Diagram-10
Diagram-11