Dostmann pH 7+ User manual

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EN

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Index
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/ŶƚƌŽĚƵĐƚŝŽŶ4
Measurement parameters4
Basic features4
pH measurement features (suited for model pH7+DHS and PC7+DHS)4
Conductivity measurement features (suited for model COND7+ and PC7+DHS)4
Data sheet5
Instrument Description6
LCD Display6
Keypad Functions6
Meter Connections7
Stability indication8
Parameter selection8
Automatic Power Off8
DHS Technology8
pH Measurement9
pH electrode information9
pH calibration consideration – Standard buffer solution9
Three-point calibration9
Calibration Intervals9
pH Meter Calibration10
Customer calibration11
example of 1.60pH and 6.50pH calibration solution11
Measurement12
Self-diagnosis information12
Factory default setting12
pH electrode maintenance13
Daily maintenance13
Calibration buffer solution13
Protect glass bulb13
Regenerate glass bulb13
ŵsŵĞĂƐƵƌĞŵĞŶƚ13
ORP14
Clean and activate ORP electrode14
Conductivity14
Cnductivity cell14
Conductivity cell constant14
Conductivity calibration solutions14
Calibration intervals15
1-point and multi-point calibration15

EN


3

Reference temperature15
Temperature coefficient15
Avoid contamination of standard solution15
Conductivity Calibration16
Customer calibration16
Measure17
Factory default setting17
Conductivity electrode maintenance18
Relations between TDS and conductivity18
Setup Menu18
Main menu18
Submenu18
Appendix I: Parameter setting & Factory default setting20
Appendix III: Self-diagnosis information………………………………………………………………………………………………………………….….20
Appendix II: Abbreviation Glossary21
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EN

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4
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Introduction
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Thanks for purchasing 7+ series portable pH/Conductivity meter. 
This meter is perfect combination of the most advanced electronics, sensor technology and software design, and is
the most cost effective portable electrochemical meter suited for industrial and mining enterprises, power plant,
water treatment engineering, environmental protection industry, etc, especially suited for application in field.
In order to use and maintain the instrument properly, please read the manual thoroughly before use. 
To improve instrument performance constantly, we reserve the right to change the manual and accessories without
giving notice in advance.
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Measurement parameters
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Measurement
parameters
pH7+DHS COND7+ PC7+DHS
pH/mV √√
Conductivity/TDS √√
Temperature √√√
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Basic features
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•The microprocessor-based portable meter features automatic calibration, automatic temperature
compensation, function set-up, self-diagnostics, automatic power-off and low voltage display. 
•The meter’s digital filter improves measurement speed and accuracy. There is reading stability display.
•The package includes portable case, meter, electrode, standard solutions and all accessories, convenient to use
in field.
•The meter is dust-proof and water-proof, meeting the IP57 rating. 
•Temperature calibration function.
•Selection of parameters to be display (only for PC7+DHS)
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pH measurement features (suited for model pH7+DHS and PC7+DHS)
•1-3 point automatic calibration, the meter provides calibration guide and automatic checking function.
•The meter is able to recognize up to 8 types of pH standard buffer solutions. There are three options of standard
buffer solution: USA series, NIST series and customer-defined solution set-up.
•The meter provides reading stability criteria.
•The meter recognize DHS Sensor
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Conductivity measurement features (suited for model COND7+ and PC7+DHS)
•1-4 point automatic calibration, the meter provides calibration guide and automatic checking function.
•The meter is able to recognize up to 4 types of conductivity standard solutions. There is customer-defined
solution set-up.
•TDS measurement
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EN

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Data sheet
Specifications Models
pH
Range
（0.00 ~ 14.00）pH
pH 7+
PC 7+
Resolution
0.1/0.01 pH
Accuracy
±0.01 pH ±1digit
Temperature
compensation
（0 ~ 100）°C（manual or automatic）
Multi-point calibration
1-3 point
Buffer value
USA: 1,68 - 4,00 - 7,00 - 10,01pH
NIST: 1,68 - 4,01 - 6,86 - 9,18pH
2 value CUSTOMER
mV
Range
±1000mV
Resolution 1mV
Accuracy
±0.1% FS ±1digit
Conductivity
Range
Conductivity: 0~200 mS/cm(divided into four ranges):
（0~199.9）μS/cm ; (200~1999) μS/cm ;
（2.00~19.99）mS/cm; （20.0~199.9）mS/cm
C0ND 7+
PC 7+
Resolution 0.1/1μS/cm 0.01/0.1 mS/cm
Accuracy
±2.0% FS
Temperature
compensation
（0 ~ 80）℃（manual or automatic）
Electrode constant
0.1 / 1 / 10 cm-1
Multi-point calibration
1-4 point
Standard solution 84 μS/cm, 1413 μS/cm, 12.88, 111,9 mS/cm
1 customer value
TDS
Range 0~100 g/L
C0ND 7+
PC 7+
Resolution 1% f.s.
TDS factor 0.4 ~ 1.0
Temperature
Range 0~100°C
pH 7+
C0ND 7+
PC 7+
Resolution 0.1℃
Accuracy ±0.5℃±1digit
Reading stability criteria Low:1.2mV/10 sec., Medium:0.6mV/10 sec., High:0.3mV/10
seconds
pH 7+
PC 7+
Power AA batteries × 3 (1.5V× 3)
IP rating IP57
Dimension & Weight
Meter: (86×196×33 )mm / 295g
EN

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Instrument Description
LCD Display
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Keypad Functions
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Momentary press ----- <1.5 seconds
Long press ----- >1.5 seconds.
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Turn on the meter
Press to turn on the meter: LCD full display → display
some parameters → display the last measurement mode.
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Turn off the meter
In the measurement mode, press and hold for 2
seconds to turn off the meter.
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Note: In the calibration mode or the parameter set-up mode, press for return to the measurement mode, then press
to turn off the meter.
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TDS
(1) — Parameter mode icons
(2) — Measurement reading
(3) — Prompts of special display mode
(4) — Units of measurement
(5) — Temperature units (°C and °F)
(6) — Units of pH and conductivity calibration value
(7) — pH and conductivity calibration value 
(8) — Temperature value,
(9) — Temperature compensation icons
ATC — automatic T compensation, 
MTC — manual T compensation
(10) — Calibration guide icon
(11) — Stability icon of readings
(12) — Battery
EN

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Keypad Operations Descriptions
Momentary press
•In the power-off mode, press this key to turn on the meter
•In the calibration mode or the parameter set-up mode, press this key to
return to the measurement mode
Long press In the measurement mode, press and hold this key for 2 seconds to turn off the
meter.
Momentary press
•pH7+DHS: press this key to select measurement mode: pH → mV,
•Cond7+: press this key to select measurement mode: COND→TDS
•PC7+DHS pH/Conductivity meter: press this key to select
measurement mode: pH → mV → COND → TDS
Momentary press In the measurement mode, press this key to enter in the calibration mode
Momentary press
•In the measurement mode, press this key to enter in the parameter
set-up main menu
•In the calibration mode, press this key to confirm calibration
•In the parameter set-up mode, press this key to select programs
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Long press
In the mode of manual temperature compensation (MTC), when press and hold
these keys, the temperature value flashes, then press this keys to change the
temperature value, and press to confirm
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Momentary press In the setup menu and submenu, these keys increases and decreases the value
of the selected parameter (up and down direction)
Meter Connections
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Models Photos Description
pH7+ DHS
•BNC socket— pH electrode or ORP electrode
•RCA socket —temperature probe
COND7 +
•BNC socket— conductivity electrode,
•RCA socket — temperature probe
PC7 + DHS
•BNC socket —pH electrode or ORP electrode,
•BNC socket— conductivity electrode,
•RCA socket— temperature probe
EN

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Stability indication
When the measuring value is stable, smiley icon appears on LCD.
If the smiley icon does not appear or flash, please do not get the reading value, or make calibration until the measuring
value is stable.
In the parameter P1.6, there are 3 criteria for stability standard:
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-Normal (default)   -High (longer time)   -Low (shorter time.)
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User can select suitable stability criteria according to different testing requirement.
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Parameter selection
Only for PC7+DHS, enter in the setup menu P6.6, one by one the parameters blinks on the top left of the LCD; 
press and keys for choose Yes (parameter enabled) or No (parameter disable) .Then press key to
confirm. Press key to return in measurement mode.
Automatic Power Off
If the meter stops operation for 20 minutes, It will turn off automatically. In the setup menu P6.8 the user has the
possibility to disable this option.
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DHS Technology
DHS technology, developed by Giorgio Bormac company, allows to save calibration data inside the memory of the pH
electrode. 
It is possible to calibrate the XS DHS electrode in laboratory, in ideal conditions, using a XS DHS meter.
Calibration data, like date, slope, model and batch number, are memorized inside the electrode.
Moving this electrode on another XS meter DHS compatible, the electrode is ready for high quality measurement,
extremely safety and without a new calibration.
Simply useful: XS Meters DHS compatible recognize automatically If a XS sensor DHS is connected. 
If not, the instrument will work as a standard pH meter.
And the same is for the electrode: Is possible to connect a XS sensor DHS on a standard XS meter (NO DHS compatible)
It will work as a standard pH electrode.
XS DHS sensors use just a BNC plug for the pH, and a RCA/Cinch plug for the temperature, exactly the same connectors
of the standard XS electrodes.
And It hasn’t the battery, so It is possible to stock the electrode as normal one.
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After connecting the XS electrode DHS, meter will recognize It automatically, and display sequentially:
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To calibrate the DHS sensor follow the calibration procedure at page 10 (pH meter calibration).
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When the DHS electrode is disconnected, display shows:
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DHS activation and disabling occur only in measurement mode.
sensor model
Batch number
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pH
No
dhs
Calibration points
dhs
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pH
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pH
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year
Slope
100
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%
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Month
day
Date of the last calibration
EN

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pH Measurement
pH electrode information
On this meter is possible to use electrode with integrated temperature sensor else link two different probes for pH and
temperature.
The BNC socket of electrode connects pH socket, RCA socket connects temperature socket. When dip the electrode in
the solution, please stir the solution briefly and allow it to stay in the solution until a stable reading is reached.
pH calibration consideration – Standard buffer solution
The meter uses two series of standard buffer solution: USA series and NIST series, and also customer-defined solution.
Please see the table below for the two series of standard buffer solution. For customer-defined solution, please select it
in setup menu parameter P1.1.
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Icons
pH standard buffer solution series
USA seriesNIST series
Three-point calibration
1,68 pH and 4.00 pH1,68 pH and 4.01 pH
7.00 pH6.86 pH
10.01 pH9.18 pH
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Three-point calibration
The instrument can perform 1-3 point calibration. The first point of calibration must be 7.00 pH (or 6.86 pH) standard
solution, then select other standard solution to perform the second and the third point calibration; the meter is able to
recognize the buffer solutions in analysis. During the calibration process, the instrument displays the slope of acidity
range and alkalinity range respectively.
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USA standardNIST standardIconsSuited range
One-point calibration7.00 pH6.86 pH
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Accuracy
≤ ±0.1pH
Two-point calibration
7.00 pH and
4.00 pH or 1,68 pH
6.86 pH and
4.01 pH or 1,68 pH
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Range<7.00pH
7.00 pH and 10.01 pH6.86 pH and 9.18 pH
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Range>7.00pH
Three-point calibration7.00 pH, 4.00 pH or 1,68
pH, 10.01 pH
6.86 pH, 4.01 pH or
1,68 pH, 9.18 pH
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Large Range
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Calibration Intervals
Calibration intervals depend on the sample, the electrode performance, and the required accuracy. For high accuracy
measurements (≤ ±0.02pH), the meter should be calibrated immediately before taking a measurement. For general
accuracy (≥±0.1pH), the meter can be calibrated and used for approximately one week before the next calibration.
The meter must be recalibrated in the following situations:
(a) New probe, or probe that is unused for a long period of time
(b) After measuring acids (pH<2) or alkaline solutions (pH>12)
(c) After measuring a solution that contains fluoride or a concentrated organic solution 
EN

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pH Meter Calibration
Press key to enter into the calibration mode, “CAL 1” blinks at the top right of LCD and “7.00 pH ”blinks at the
bottom right of LCD, indicating using pH 7.00 buffer solution to make the 1st point calibration.
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Rinse pH electrode in pure water, allow it to dry, and submerge it in pH 7.00 buffer solution. Stir the solution gently and
leave it in the buffer solution until a stable reading is reached. The meter’s display will show scanning and locking process
of calibration buffer solution at the bottom right of LCD. 
Er 2 displays if press key before the value is stable. 
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When the meter locks 7.00 pH, stable icon displays on LCD. Press
key to calibrate the meter.
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“End” icon appears after calibration is done. After the 1st point calibration, the meter’s display will show at the top right
a blinking CAL2, and show at the bottom right blinking 4.00pH and 10.01pH alternately, indicating using pH4.00 or
pH10.01 buffer solution to make the 2nd point calibration. 
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Take out pH electrode，rinse it in pure water, allow it to dry, and submerge it in pH4.00 buffer solution. 
Stir the solution briefly and allow it to stay in the buffer solution until a stable reading is reached. The meter’s 
display will show scanning and locking process of calibration buffer solution at the bottom right of LCD. When the meter
locks 4.00 pH, stability icon displays on LCD. Press key to calibrate the meter. 
Display shows “End” and slope. 
The meter’s display will show at the top right a blinking CAL3, and show at the bottom right blinking 10.01pH, indicating
using pH10.01 buffer solution to make the 3rd point calibration.
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Take out pH electrode，rinse it in pure water, allow it to dry, and submerge it in pH10.01 buffer solution. Stir the solution
briefly and allow it to stay in the buffer solution until a stable reading is reached. The meter’s will show scanning and
locking process of calibration buffer solution at the bottom right of LCD. When the meter locks 10.01 pH, stable
icon appears on LCD. Pr key to calibrate the meter.
Display shows “End” icon and slope. Than the meter goes automatically to the measurement mode, displays stable
measuring value and calibration guide icons.
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During the calibration process, press key to exit from the calibration mode. The meter can perform one-
point, two-point and three-point calibration. Calibration guide icons appear on LCD.
EN