Apera Instruments PH910 User manual

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PH910 Benchtop pH Meter
Instruction Manual
PH910 Benchtop pH Meter
EC910 Benchtop Cond. Meter
PC910 Benchtop pH/Cond. Meter
APERA INSTRUMENTS (Europe) GmbH
www.aperainst.de

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Table of Contents
1Introduction..........................................................................................................................- 4 -
1.1 Measuring parameters ..................................................................................................- 4 -
1.2 Basic features...............................................................................................................- 4 -
1.3 pH measurement features ............................................................................................- 4 -
1.4 Conductivity measurement features..............................................................................- 4 -
2Configuration .......................................................................................................................- 5 -
3Specifications.......................................................................................................................- 6 -
3.1 Technical parameters....................................................................................................- 6 -
3.2 Other technical parameters...........................................................................................- 6 -
4Instrument Description .........................................................................................................- 7 -
4.1 LCD display ..................................................................................................................- 7 -
4.2 Keypad functions ..........................................................................................................- 8 -
4.3 Meter sockets ...............................................................................................................- 9 -
4.4 Display mode..............................................................................................................- 10 -
4.5 Data storage, recall and delete ...................................................................................- 10 -
4.6 Manually adjust temperature.......................................................................................- 12 -
5pH measurement ...............................................................................................................- 12 -
5.1 pH Electrode Information ............................................................................................- 12 -
5.2 pH calibration related information ...............................................................................- 14 -
5.3 pH meter calibration (take three-point calibration as an example)...............................- 16 -
5.4 Customized calibration (take 2.00pH and 7.30pH calibration solution as an example) - 17 -
5.5 Self-diagnosis Information ..........................................................................................- 18 -
5.6 Sample measurement.................................................................................................- 19 -
6mV Measurement...............................................................................................................- 20 -
6.1 ORP measurement .....................................................................................................- 20 -
6.2 Notes for ORP measurement......................................................................................- 20 -
6.3 Ion potential measurement..........................................................................................- 21 -
7Conductivity Measurement.................................................................................................- 21 -
7.1 Conductivity probe information....................................................................................- 21 -
7.2 Conductivity calibration related information.................................................................- 21 -
7.3 Conductivity meter calibration (take 1413μS/cm calibration as an example) ...............- 23 -
7.4 Customized calibration (take 10μS/cm standard solution as an example)...................- 23 -
7.5 Self-diagnosis information...........................................................................................- 24 -
7.6 Solution measurement ................................................................................................- 25 -

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7.7 Conductivity probe maintenance.................................................................................- 26 -
8Parameter setting ..............................................................................................................- 27 -
8.1 Main menu and submenu ...........................................................................................- 27 -
8.2 Operation....................................................................................................................- 27 -
8.3 Content of parameter setting.......................................................................................- 28 -
9USB communication ..........................................................................................................- 29 -
9.1 Install Software ...........................................................................................................- 29 -
9.2 Software Interface.......................................................................................................- 29 -
9.3 Operation Keys of PC-Link..........................................................................................- 29 -
10 Recommended pH Electrodes for Specific Applications..................................................- 30 -
11 Recommended Conductivity Electrodes for Specific Applications...................................- 31 -
12 Warranty.........................................................................................................................- 31 -
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.

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1 Introduction
Thank you for purchasing our PH910 Benchtop pH Meter.
Before using this meter, please read this manual carefully in order to help use and maintain it correctly.
On the basis of improving instrument of performance constantly, we reserve the right of changing the
content of this manual and accessories in case of not notifying in advance.
This meter is a perfect combination with advanced electronic technology, sensor technology and software
design, and is the most cost effective benchtop meter which is suitable for pH and conductivity
measurement of water solution in laboratory.
1.1 Measuring parameters
Parameter and configuration
PH910
EC910
PC910
pH/mV
√
√
Conductivity/TDS/Salinity
√
√
Temperature
√
√
√
Electrode Stand
√
√
√
1.2 Basic features
⚫Clear TFT color display
⚫User-friendly operating navigation by graphics and texts
⚫Multi language operating system (English, German & Chinese)
⚫Smiling icon indicates the reading stability, including automatical lock function.
⚫With built-in microprocessor chip, the meter has intelligent functions such as automatic calibration,
automatic temperature compensation, function setting, self-diagnosis and data logger.
⚫PC910 meter can measure and display pH & conductivity readings simultaneously.
1.3 pH measurement features
⚫1~3 point automatic calibration with calibration instruction and automatic check functions.
⚫Automatically recognize pH buffer solution. 3 series buffer solution selectable: USA series, NIST
series and China series, as well as customized solutions.
⚫Automatically display electrode slope.
1.4 Conductivity measurement features
⚫1~ 4 point automatic calibration with calibration instruction and automatic checking functions.
⚫Automatically recognize conductivity standard solution. 2 series standard solution selectable: USA
and CH, as well as customized solution.
⚫Single-tap switch among conductivity, TDS, and salinity.

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2 Configuration
Description
Quantity
PH910
EC910
PC910
2.1
PH910 pH meter
1
√
2.2
EC910 conductivity meter
1
√
2.3
PC910 pH/conductivity meter
1
√
2.4
602 flexible electrode holder
1
√
√
√
2.5
LabSen211 glass pH combination electrode
1
√
√
2.6
MP500 temperature probe
1
√
√
2.7
2301T-F conductivity electrode (ATC, K=1.0)
1
√
√
2.8
pH buffer solution (4.00/7.00/10.01pH/50mL)
1 bottle
each
√
√
2.9
Conductivity standard solution
(84μS/1413μS/12.88mS/50mL)
1 bottle
each
√
√
2.10
PCLink-910 Flash Disk
1
√
√
√
2.11
USB communication cable
1
√
√
√
2.12
9V power adapter
1
√
√
√
2.13
Instruction manual
1
√
√
√
2.14
Quick manual
1
√
√
√

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3 Specifications
3.1 Technical parameters
Technical Parameters
Model
pH
Measuring Range
(0.00 ~ 14.00) pH
PH910
PC910
Resolution
0.1/0.01 pH
Accuracy
±0.01 pH ±1 digit
Temperature
Compensation Range
(0 ~ 100) °C (Auto. or Manual)
Calibration point
1~3 points
mV
Measuring Range
±2000mV
Resolution
1mV
Accuracy
±0.1% FS ±1 digit
Cond.
Measuring Range
Conductivity: 0~200 mS/cm, divided into five
ranges, automatically switch measuring range.
(0~19.99) μS/cm; (20.0~199.9) μS/cm;
(200~1999) μS/cm; (2.00~19.99) mS/cm;
(20.0~199.9) mS/cm
TDS: (0 ~ 100) g/L;
Salinity: (0 ~ 100) ppt
EC910
PC910
Resolution
0.01/0.1/1μS/cm; 0.01/0.1 mS/cm
Accuracy
±1.0% FS ±1 digit
Temperature
Compensation Range
(0 ~ 50) °C (Auto. or Manual)
Cell constant
0.1 / 1 / 10 cm-1
Temp.
Measuring Range
0~100 °C
PH910
EC910
PC910
Resolution
0.1°C
Accuracy
±0.5 °C±1 digit
3.2 Other technical parameters
Data Storage
200 groups
Storage Content
Number, measuring value and temperature value
Power
DC9V/600mA
Dimension & Weight
Meter: (195×215×100)mm / 0.9kg

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4 Instrument Description
4.1 LCD display
pH measurement interface
①pH measurement
②pH measuring value
③Temperature measuring value
④pH electrode slope
⑤Calibration solution indication icon
⑥Used data storage
⑦Temperature compensation icon,
MTC-manual temperature compensation
ATC-auto. temperature compensation
⑧Auto. lock on icon
⑨Stable reading icon
⑩Date and time
⑪Auto. data log
⑫Storage icon and number
Conductivity measurement interface
①Conductivity measurement
②Conductivity measuring value and
unit
③Temperature measuring value
④Conductivity parameter：
1.0 - conductivity cell constant
25.0°C - reference temperature
2.00% - temperature compensation
Coefficient
⑤Calibration solution indication icon
⑥Used data storage
⑦Temperature compensation icon,
MTC-manual temperature compensation
ATC-auto. temperature compensation
⑧Auto. Hold
⑨Stable reading icon
⑩Date and time
⑪Auto. data log
⑫Storage icon and number

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TDS measurement interface
Salinity measurement interface
pH/Cond. measurement interface
mV measurement interface
4.2 Keypad functions
Diagram-1
Keypad operation mode:
Short press—Press the <2s, buzzer makes a beep;
Long press—Press key >2s, buzzer makes a beep when pressing the button,
another beep will ring after holding the key for 2 seconds.
①—TDS measurement ②—TDS factor 0.71
Salinity factor 0.5

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Chart -1 Keypad operations and functions
Keypad
Operations
Functions
Short press
⚫Power on/off
Short press
Press key to select measurement mode:
⚫PH910: pH→mV
⚫EC910: Cond→TDS→Salt
⚫PC910: pH→mV→Cond→TDS→Salt→pH/Cond
Long press
⚫ Press key to enter temperature adjustment mode (for manual
temperature compensation)
Long press
⚫In measurement mode, press key to enter calibration mode
Short press
⚫Cancel operation and return to measurement mode;
Short press
⚫In measurement mode: press key to enter parameter setup main menu;
⚫In calibration mode: press key to conduct calibration;
⚫In main menu mode: press key to enter submenu;
⚫In submenu mode: press key to enter parameter setup;
⚫In parameter setup mode: press key to confirm parameter change;
⚫In temperature adjustment mode: press key to confirm temperature
value.
Short press
⚫In measurement mode: press key to store measuring value,
press key to recall;
⚫In recall(RM) mode: press or key to turn page;
⚫In menu mode: press key to select items;
⚫In temperature adjustment mode: press key to change temperature
value, hold key for fast change.
4.3 Meter sockets
Socket Type
Information
①
BNC
Connect pH or ORP combination electrode
②
RCA
Connect temperature sensor (for pH)
①+②
BNC+RCA
connect pH/ATC 3-in-1 combination electrode
③
Ф4 banana
Connect reference electrode
④
BNC
Connect conductivity electrode
⑤
RCA
Connect temperature sensor (for conductivity)
④+⑤
BNC+RCA
connect with Cond/ATC electrode
⑥
USB
Connect PC
⑦
Ф2.5 power supply
Connect DC9V adaptor (inside “＋” outside “－”)

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4.4 Display mode
4.4.1 Reading stable display mode
When the measuring value is stable, smiley icon appears
and stays on LCD screen, see Diagram – 3. If the smiley icon
does not appear or flash, please do not get readings or make
calibration until the measuring value is stable.
4.4.2 Auto. lock on display mode
In parameter setting 3.1, set “Reading with HOLD” to “ON”,
when icon stably display for more than 10 seconds, the meter will lock the value automatically and
display HOLD icon, see Diagram – 4(b). In HOLD mode, press key to cancel auto lock.
4.5 Data storage, recall and delete
4.5.1 Storage
(a) Manual data logger
Set “auto. timing” to “00:00:00”, Press key to store, icon 6 displays on the down
right corner of LCD screen which means it’s the 6th group data. see Diagram – 5(a); Each meter can
store 200 groups data. For single parameter display mode, 1 serial number corresponds to 1 group
measuring vale. For dual parameter display mode (means pH+Cond. meter display mode), 1 serial
number corresponds to 2 groups measuring value (pH + conductivity). So for this type of meter,
Diagram-3
(a)
(b)
Diagram-4
Model
Meter sockets
PH910
① ② ③ ⑥⑦
EC910
④ ⑤ ⑥⑦
PC910
① ② ③ ④ ⑤ ⑥⑦
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16:26:42
2020-01-18
16:26:42

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actual store data is 200 groups, but storage number will be less than 200. If press key again
when storage value is full, icon will flash, see Diagram –5(c) to indicate store memory is already
full and need to be deleted for new store value.
(b) Auto. timing data logger
Select “Timer” in parameter setting 3.2 and set the data logging interval time (by every X seconds or
minutes), for example, 3 minutes. In auto timing data logo mode, shows up, press to start
auto. data logger, flashes, the first set of measurement data is stored, then every three minutes one
set of data will be stored and the storage number will be automatically increased. Press again to
stop auto. data logger. In this mode, the manual data logging is invalid.
4.5.2 Recall
Press key, meter will display stored 6 groups measuring value, see Diagram – 5(b), press
or key to turn page. Every page displays 8 groups data.
4.5.3 Delete
Data need to be deleted when storage memory is full, otherwise no more data can be stored. In parameter
setting 3.3 select “Yes” and press key, see Diagram – 5(d) to delete all stored value. . Note:
when connect the meter via USB cable to store the measured values to the computer, there
is no limitation on the number of data storage, either manual or automatic storage.
（a）（b）
(C) Diagram-5 (d)

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4.6 Manually adjust temperature
In MTC mode, long press key to enter temperature regulation mode. Press or key
to adjust temperature value. Press and hold the key for fast adjustment. Press key to confirm
and return to measurement mode.
5 pH measurement
5.1 pH Electrode Information
The meter comes with a LabSen 211 pH combination electrode and MP500 temperature probe,
which enables the automatic temperature compensation. The LabSen pH electrodes are made with
proprietary sensor technologies and premium materials from Switzerland. LabSen 211 pH electrode
is designed for high-precision lab and field pH measurement of general water solutions. The
electrode is compatible with TRIS buffers.
For testing pH of special samples such as viscous (sticky), strong acidic or alkaline solutions,
solutions at high or low temperature (>50˚C or <10˚C), solid samples, turbid solutions, low ion-
concentration solutions & etc…specialized pH electrodes are necessary in order to achieve reliable
results. Regular pH electrodes in these special applications usually would generate inaccurate and
unstable measurements, and may be damaged by the samples, or even be non-applicable for
testing at all.
Please refer to Section 10 for ideal pH electrodes to use for other specific applications.
5.1.1 Features of LabSen 211 pH Electrode
⚫Built with LabSen S-type hemispherical glass membrane, featuring low resistance (fast response)
and high firmness
⚫No more air bubbles inside the glass membrane thanks to the Swiss blue gel electrolyte.
⚫The long-life reference system significantly increases measuring stability and extends service life.
5.1.2 Technical Specifications of the LabSen211 pH Electrode
Measuring Range
0-14 pH
Junction
Ceramic
Temperature Range
23 to 212 ˚F (-5 to 100
°C)
Reference Solution
3M KCL
Membrane Types
S
Soaking Solution
3M KCL
Body Material
Lead-free Glass
Membrane Resistance
<150 MΩ
Reference
Long Life
Electrode Dimension
(Φ12×120) mm
Connector and cable
length
BNC/1m

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5.1.3 Technical Specifications of the MP500 Temperature Probe
Temperature Range
14 to 230 ˚F (-10 to 110 °C)
Body Material
Stainless Steel
Sensor
30 KΩ thermistor
Probe Dimension
(Φ5×145) mm
Connector
RCA
Connector and cable length
BNC/1m
5.1.4 Use the Electrode
1. Insert the blue BNC connector of the electrode to the BNC socket of your
pH meter while twisting clockwise until it`s locked, plug the RCA
connector into the “TEMP” sockets. Please note not to pull the cables in
case of poor contact. Please keep the connectors clean and dry.
2. Before measuring, twist off the storage bottle cap (see graph on the right),
pull out the electrode and rinse it off with distilled or deionized water.
3. Unplug the blue rubber plug to maintain a smooth electrolyte flow.
4. Stir the solution briefly to eliminate the air bubbles and in this way, a
stable measurement will be reached fast.
5. Perform at least a two-point calibration before measuring after connecting the new electrode to
your pH meter.
6. After using, put the electrode back into the storage bottle, twist on the bottle cap, and plug in
the refilling hole.
5.1.5 Maintenance
1. When not in use, the electrode should be soaked in the storage bottle containing 3M KCL
soaking solution (SKU: AI1107) to keep the glass membrane and junction in a healthy
condition. Clean the bottle and replace the soaking solution if it gets contaminated. The
electrode should never be stored in pure water such as deionized or distilled water.
2. The reference solution will run low as you use the electrode. Whenever the solution level falls
to 1/2 height of the electrode, add 3M KCL solution (SKU: AI1107) to the refilling hole (unplug
the blue rubber plug) using a syringe or pipette.
3. The electrode is only as accurate as it is clean. Always thoroughly rinse off the electrode
before and after each measurement with pure water in a container or with a wash bottle.

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4. For tough contaminants, soak the electrode in Apera cleaning solution (AI1166) for 30 minutes.
Then use a soft brush to remove the contaminants. Afterwards, soak the electrode in 3M KCL
solution (SKU: AI1107) for at least 1 hour. Rinse it off, then re-calibrate it before using again.
5. The connector of the electrode should be kept clean and dry. If contaminated, please clean it
with medical cotton and isopropyl alcohol and blow-dry it to prevent short circuit of the
electrode or slow response of the electrode.
6. The electrode should avoid testing strong acid and strong alkali solutions, as well as
dehydrating media such as absolute ethanol and concentrated sulfuric acid. If testing such
solutions, the immersion time should be minimized and the electrode should be carefully
cleaned after use.
7. Every pH electrode will eventually age and fail. The typical service life of Apera pH electrodes
is 12 to 24 months depending on the frequency of usage and how well you keep it clean and
properly stored. We recommend replacing your electrode every 12-18 months to ensure the
best performance.
5.2 pH calibration related information
5.2.1 Standard buffer solution
The instrument adopts three series standard buffer solution, USA, NIST and CH series, and also
customized solution. Please see Chart – 2 for the three series of standard buffer solution. The detail
of customized solution, see clause 5.4.
Chart -2 pH standard buffer solution series
Calibration indication icons
pH standard buffer solution series
USA series
NIST series
CH series
Three-point
calibration
or
pH 4.00 or 1.68
pH 4.01 or 1.68
pH 4.00 or 1.68
pH 7.00
pH 6.86
pH 6.86
or
pH 10.01 or 12.45
pH 9.18 or 12.46
pH 9.18 or 12.46
Note: calibration indication icons are example of USA series.
5.2.2 Three-point calibration
The instrument can perform 1~3 point calibration. In three-point calibration mode, the first point
calibration must use 7.00 pH (or 6.86 pH) standard solution, then select other standard solution to
perform the second and the third point calibration. See chart – 3. Users can choose two-point
calibration of pH 7.00 and pH 1.68 for strong acidic solutions (<pH 2), or pH 7.00 and pH 12.45 for
strong alkaline solutions (>pH 12).

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Chart -3 Three-point calibration mode
USA standard
NIST standard
CH standard
Applicable range
One-point
calibration
pH 7.00
pH 6.86
pH 6.86
Accuracy
≤± 0.1pH
Two-point
calibration
pH 7.00 and
pH 4.00/1.68
pH 6.86 and
pH 4.01/1.68
pH 6.86 and
pH 4.00/1.68
< pH 7.00
pH 7.00
and pH 10.01/12.45
pH 6.86 and
pH 9.18/12.46
pH 6.86 and
pH 9.18/12.46
> pH 7.00
Three-point
calibration
pH 7.00,
pH 4.00/1.68 and
pH 10.01/12.45
pH 6.86,
pH 4.01/1.68 and
pH 9.18/12.46
pH 6.86,
pH 4.00/1.68 and
pH 9.18/12.46
pH 0 – 14.00
5.2.3 Calibration information display
1. Automatically display electrode slope in measurement
interface
⚫ Display average slope after two or three point calibration
⚫ Dose not display slope after one point calibration
2. Display last calibration data in pH submenu clause 1.3
5.2.4 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 meaustements (≤ ±0.02pH), the
meter should be calibrated before test every time; For ordinary-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:
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 base (pH>12) solutions.
c) After measuring fluoride-containing solution and strong organic solution
d) There is a significant difference between the temperature of the test sample and the temperature of
the buffer solution that is used in the last calibration.
2020-01-18
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5.3 pH meter calibration (take three-point calibration as an example)
Long press key to enter calibration mode, as shown
in left graph. Rinse pH probe in purified water, remove
excess water by shaking or filter paper. Press
key to confirm.
Submerge probe in pH7.00 buffer solution. Stir the
solution briefly and allow it to stay in the buffer solution
until appears and stays. Press key to finish
calibration.
Rinse pH probe in purified water, allow it to dry by shaking
or filter paper. Press key to confirm. If only need
one point calibration, press key to return to
measurement mode.
Submerge probe in pH4.00 buffer solution. Stir the
solution briefly and allow it to stay in the buffer solution
until appears and stays. Press key to finish
calibration.
Rinse pH probe in purified water, remove excess water by
shaking or filter paper. Press key to confirm. If
only need two point calibration, press key to
return to measurement mode.

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Submerge probe in pH10.01 buffer solution. Stir the
solution briefly and allow it to stay in the buffer solution
until appears and stays. Press key to finish
calibration.
Calibration completed, instrument goes back to
measurement mode.
5.4 Customized calibration (take 2.00pH and 7.30pH calibration solution as
an example)
1. Select User in parameter setting 1.1, press key to
return to measurement mode.
2. Long press key to enter calibration mode, as
shown in left graph. Rinse pH probe in purified water,
remove excess water by shaking or filter paper. Press
key to confirm.
3. Submerge probe in pH2.00 buffer solution. Stir the
solution briefly and allow it to stay in the buffer solution
until appears and stays. Press or
key to adjust measuring value to 2.00pH. Press
key to finish calibration.
4. Rinse pH probe in purified water, remove excess water
by shaking or filter paper. Press key to confirm.
If only need one point calibration, press key to
return to measurement mode.

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Notes:
(a) The meter can perform 1–2-point customized calibration. When the 1st point calibration is done,
press key, the meter exits from calibration mode. This is one-point customized calibration.
(b) The meter does not have the function to recognize customized calibration solution. But it requires
the error of customized calibration solution ≤1pH, the difference between two calibration solution
≥1pH, otherwise the meter will display self-diagnostic error.
(c) The pH value of customized solution is a value in a certain fixed temperature. The meter has to
perform calibration and measurement at the same temperature to avoid error.
(d) In manual temperature compensation mode, the temperature value should be adjusted before
calibration. It can not be adjusted during calibration process.
5.5 Self-diagnosis Information
During the process of calibration and measurement, the
meter has self-diagnosis functions, see chart – 4. Diagram- 6 for detailed information.
Diagram-6
5. Submerge probe in pH7.30 buffer solution. Stir the
solution
briefly and allow it to stay in the buffer solution until
appears and stays. Press or key to
adjust measuring value to 7.30pH. Press key to
finish calibration.
6.Calibration completed, instrument goes back to
measurement mode.

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Chart -4 Self-diagnostic information of pH measurement mode
Self-diagnostic
information
Description
Check up
buffer error
Wrong pH buffer solution or exceed
the recognition range of the meters
1.Check if the pH buffer solution is correct
2. Check if the connection between meter
and probe is good
3. Check if the probe is failed
no stable
Press key when measuring
value is not stable.
Press when icon appears
electrode error
1. The measuring value is not stable
for long time (≥3min)
2. Electrode slope <75%
1.Check the probe bulb and make sure
there is no air bulb in it
2.Replace the pH probe with a new one
Note: “electrode error” also includes the situation where electrodes get aged or worn out.
5.6 Sample measurement
5.6.1 Rinse pH probe in purified water, allow it to dry, and submerge it in tested solution. Stir the
solution briefly and allow it to stay in the tested solution until icon appears on LCD and a
stable reading is reached. The reading is the pH value of tested solution. Diagram–7 is the
calibration and measurement process of pH meter.
Diagram-7
3 r d point
calibration
Submerge the
probe in pH4.00
solution, press
key when
icon appears.
Press
key to turn on
the meter
Press
Key to enter
calibration
mode
1st point calibration
completed, press
key to enter
into measurement
mode
Solution
Measurement
2nd point
calibration
1 st point
calibration
Submerge the
probe in pH7.00
solution, press
key when
icon appears.
Submerge the
probe in pH10.01
solution, press
key when
icon appears.
2nd point calibration
completed, press
key to enter
into measurement
mode
3rd point calibration
completed, meter
auto. enters into
measurement mode

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5.6.2 pH isothermal measurement principle
The closer the temperature of the sample solution to the calibration solution, the more accurate the
measurements will be. Please be aware of this principle.
5.6.3 Restore to factory default setting
Instrument has a factory default setting function,
please refer to parameter setting clause 1.4
(see Diagram-8). With this function, all calibration data
is deleted and the meter will be calibrated to the theory
value (pH value of zero electric potential is 7.00, the
slope is 100%). Some function settings restore to the
original value (refer to clause 8.3). When calibration or
measurement fails, please restore the meter to factory
default setting and then perform re-calibration or measurement. Please note that all the data deleted will
not be retrievable if the meter is restored to factory default setting.
6 mV Measurement
6.1 ORP measurement
Press key, and switch the meter to mV measurement mode. Connect ORP probe (need to
purchase it separately) and dip it in sample solution, stir the solution briefly and allow it to stay in the
solution until icon appears. The reading obtained is ORP value.ORP stands for Oxidation
Reduction Potential. It means oxidation-reduction potential of solution.
ORP is the measurement index for the oxidation-reduction ability of water solution. Its unit is mV.
6.2 Notes for ORP measurement
6.2.1 ORP measurement does not require calibration. When the user is not sure about ORP
probe quality or measuring value, use ORP standard solution to test mV value and see whether
ORP probe or meter works properly.
6.2.2 Clean and activate ORP probe: After the probe has been used over long period of time, the
platinum surface of the ORP probe will get polluted which causes inaccurate measurement and
slow response. Please refer to the following methods to clean and activate ORP probe:
(a) For inorganic pollutant, submerge the probe in 0.1mol/L dilute hydrochloric acid for 30 minutes, wash
it in purified water, and then submerge it in electrode soaking solution for 6 hours.
(b) For organic or lipid pollutant, clean the platinum surface with detergent, then wash it in purified water,
then submerge it in electrode soaking solution for 6 hours.
(c) For heavily polluted platinum surface on which oxidation film is formed, polish the platinum surface
with toothpaste, then wash it in purified water, then submerge it in electrode soaking solution for 6
hours.
Diagram-8