GHM Greisinger GMH 3431 User manual

H72.0.01.6C-06
GHM GROUP - Greisinger
GHM Messtechnik GmbH | Hans-Sachs-Str. 26 | 93128 Regenstauf | GERMANY
Tel.: [phone] | [email protected] | www.greisinger.de

Please carefully read these instructions before use!

Please consider the safety instructions!

Please keep for future reference!
as of version 1.3 GMH 3431
WEEE-Reg.-Nr. DE 93889386
Operating manual
Conductivity measuring device

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Index
1GENERAL NOTE......................................................................................................................................................3
2SAFETY......................................................................................................................................................................3
2.1 INTENDED USE.......................................................................................................................................................3
2.2 SAFETY SIGNS AND SYMBOLS................................................................................................................................3
2.3 SAFETY GUIDELINES..............................................................................................................................................3
3PRODUCT SPECIFICATION..................................................................................................................................4
3.1 SCOPE OF SUPPLY ..................................................................................................................................................4
3.2 OPERATION AND MAINTENANCE ADVICE..............................................................................................................4
4HANDLING................................................................................................................................................................5
4.1 DISPLAY ELEMENTS...............................................................................................................................................5
4.2 PUSHBUTTONS.......................................................................................................................................................5
4.3 CONNECTIONS .......................................................................................................................................................5
4.4 POP-UP CLIP...........................................................................................................................................................6
5START OPERATION................................................................................................................................................6
6PRINCIPLES OF THE MEASUREMENTS...........................................................................................................7
6.1 BASICS ABOUT CONDUCTIVITY .............................................................................................................................7
6.2 CONDUCTIVITY MEASUREMENT............................................................................................................................7
6.3 RESISTIVITY MEASUREMENT.................................................................................................................................7
6.4 TDS MEASUREMENT..............................................................................................................................................7
6.5 SALINITY MEASUREMENT......................................................................................................................................7
6.6 ELECTRODES /MEASURING CELLS .......................................................................................................................8
6.6.1 Design............................................................................................................................................................8
6.6.2 Calibration / Adjustment of measuring cells..................................................................................................8
6.7 TEMPERATURE COMPENSATION ............................................................................................................................8
6.7.1 Temperature compensation “nLF” according to EN 27888 .........................................................................8
6.7.2 Linear temperature compensation and determination of temperature coefficient “t.Lin“ ............................8
7CONFIGURATION...................................................................................................................................................9
8ADJUSTMENT OF TEMPERATURE INPUT.....................................................................................................10
9REAL TIME CLOCK (“CLOC”)...........................................................................................................................10
10 AUTOMATIC ADJUSTMENT/CALIBRATION OF CELL CORRECTION..............................................10
11 GLP........................................................................................................................................................................11
11.1 CALIBRATION INTERVAL (C.INT).....................................................................................................................11
11.2 CALIBRATION STORAGE (READ CAL).............................................................................................................11
12 ACCURACY CHECK / ADJUSTMENT SERVICE ........................................................................................12
13 UNIVERSAL OUTPUT .......................................................................................................................................12
13.1 SERIAL INTERFACE ..........................................................................................................................................12
14 ERROR AND SYSTEM MESSAGES................................................................................................................13
15 RESHIPMENT AND DISPOSAL.......................................................................................................................14
15.1 RESHIPMENT ....................................................................................................................................................14
15.2 DISPOSAL INSTRUCTIONS.................................................................................................................................14
16 SPECIFICATION.................................................................................................................................................14

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1 General Note
Read this document carefully and get used to the operation of the device before you use it. Keep this
document within easy reach near the device for consulting in case of doubt.
2 Safety
2.1 Intended Use
The device is designed for measuring conductivity, resistivity, salinity and TDS in fluids –using a
permanently connected electrode (measuring cell).
It is designed for the mobile use or the stationary operation in a controlled electromagnetic environment (lab).
Personnel which starts up, operates and maintains the device has to have sufficient knowledge of the
measuring procedure and the meaning of the resulting measured values, this manual delivers a valuable
help for this. The instructions of the manual have to be understood, regarded and followed.
To be sure that there´s no risk arising due to misinterpretation of measured values, the operator must have
further knowledge in case of doubt - the user is liable for any harm/damage resulting from misinterpretation
due to insufficient knowledge.
The manufacturer will assume no liability or warranty in case of usage for other purpose than the intended
one, ignoring this manual, operating by unqualified staff as well as unauthorized modifications to the device.
2.2 Safety signs and symbols
Warnings are labelled in this document with the followings signs:
Caution! This symbol warns of imminent danger, death, serious injuries
and significant damage to property at non-observance.
Attention! This symbol warns of possible dangers or dangerous
situations which can provoke damage to the device or environment at
non-observance.
Note! This symbol point out processes which can indirectly influence
operation, possibly cause incorrect measurement or provoke
unforeseen reactions at non-observance.
2.3 Safety guidelines
This device has been designed and tested in accordance with the safety regulations for electronic devices.
However, its trouble-free operation and reliability cannot be guaranteed unless the standard safety measures
and special safety advises given in this manual will be adhered to when using the device.
1.
Trouble-free operation and reliability of the device can only be guaranteed if the device is not subjected
to any other climatic conditions than those stated under "Specification".
If the device is transported from a cold to a warm environment condensation may cause in a failure of
the function. In such a case make sure the device temperature has adjusted to the ambient temperature
before trying a new start-up.
2.
If there is a risk whatsoever involved in running it, the device has to be switched off
immediately and to be marked accordingly to avoid re-starting.
Operator safety may be a risk if:
- there is visible damage to the device
- the device is not working as specified
- the device has been stored under unsuitable conditions for a longer time.
In case of doubt, please return device to manufacturer for repair or maintenance.

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3.
When connecting the device to other devices the connection has to be designed most thoroughly as
internal connections in third-party devices (e.g. connection GND with protective earth) may lead to
undesired voltage potentials that can lead to malfunctions or destroying of this device and the
connected devices.
This device must not be run with a defective or damaged power supply unit.
Danger to life due to electrical shock!
4.
Do not use these products as safety or emergency stop devices or in any other
application where failure of the product could result in personal injury or material damage.
Failure to comply with these instructions could result in death or serious injury and
material damage
5.
This device must not be used at potentially explosive areas!
The usage of this device at potentially explosive areas increases danger of deflagration,
explosion or fire due to sparking.
6.
This device is not constructed for use in medical applications.
3 Product Specification
3.1 Scope of supply
GMH 3431, incl. 9V-battery
Operating manual
3.2 Operation and maintenance advice
1. Battery operation:
If and ‘bAt’ is shown in the lower display the battery has been used up and needs to be replaced.
However, the device will operate correctly for a certain time. If ‘bAt’ is shown in the upper display the
voltage is too low to operate the device; the battery has been completely used up.
The battery has to be taken out, when storing device above 50°C. We recommend taking out
battery if device is not used for a longer period of time.
After recommissioning the real-time clock has to be set again.
2. Treat device and sensor carefully. Use only in accordance with above specification. (do not throw, hit
against etc.). Protect plug and socket from soiling.
3. Mains operation with power supply:
When using a power supply please note that operating voltage has to be 10.5 to 12 V DC.
Do not apply overvoltage!! Cheap 12V-power supplies often have excessive no-load voltage.
We, therefore, recommend using regulated voltage power supplies.
Prior to connecting the power supply to the mains make sure that the operating voltage stated
at the power supply is identical to the mains voltage.
The external supply must not have a galvanic connection to the measurement medium, as this
can influence the measurement and thus lead to measurement errors.
Trouble-free operation is guaranteed by our power supply GNG10/3000.

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4 Handling
4.1 Display elements
1
Main display: conductivity (mS/cm, µS/cm)
resistivity (kΩcm)
TDS / total dissolved solids (mg/l)
salinity (SAL)
2
Secondary display: measuring value temperature
3
Arrows to selected measuring unit
4
Warning signal: indicates low battery or missing
calibration
5
Display elements to show minimum / maximum /
memorized measuring value
6
nLF, Lin: display element for selected
temperature compensation
7
%/K, 1/cm: additional configuration units
4.2 Pushbuttons
On / Off key
press shortly: switch on/off instrument
Set / Menu:
press shortly: change-over between measuring units
(only if „InP: SEt“ is selected)
press for 2 sec. (menu): invoke configuration menu
+
min/max when taking measurements:
press shortly: min. or max. value is displayed
press for 2 sec: the corresponding value is deleted
Configuration:
to enter values or change settings
CAL: only at mode ‘cond’=conductivity:
press for 2 sec: start cell correction adjustment
Store/Quit:
Measurement: hold and save current measuring value
(‘HLD’ is displayed)
Set/Menu: confirm settings, return to measuring
4.3 Connections
Universal output: interface (see chapter 13
“Universal output“)
Permanently connected measuring cell with
integrated temperature probe
Power supply: The mains socket (1.9 mm inner diameter) is located at the left side of the
instrument for 10.5-12 V DC supply
All contacts have to be protected against dirt and moisture!
MAX DIF
MIN HLD
%
°C
°F
S
Logg %/K AL
mS
nLF
SAL mg/l
1/cm
Lin
kOhm 
1 2 3
4 5 6
ON
OFF max
Store
CAL
min
Set
Menu Quit

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4.4 Pop-up clip
Handling:
-Pull at label “open” in order to swing open the pop-up clip.
-Pull at label “open” again to swing open the pop-up clip further.
Pop-up clip closed
Pop-up clip at position 90°
Pop-up clip at position 180°
Function:
-The device with a closed pop-up clip can be plainly laid onto a table or attached to a belt, etc.
-The device with pop-up clip at position 90° can be set up on a table, etc.
-The device with pop-up clip at position 180° can be suspended from a screw or the magnetic holder
GMH 1300.
Device attached to a belt
Device set up on a table
Device suspended from
magnetic holder
GMH 1300
5 Start Operation
Turn device on via key.
After segment test the device displays some information on its configuration:
if cell correction scale was changed (cell correction scale unequal 1.000)
(see chapter 10 Automatic adjustment/calibration of cell correction)
if zero point or slope correction is active
(see chapter 8 Adjustment of temperature input)
After that the device is ready for measuring.

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6 Principles of the measurements
6.1 Basics about conductivity
Definition of conductivity: The ability of a material to conduct electric current:   

l: length of the material
A: diameter
R: measured resistance
Unit 󰇟󰇠  
  , common for liquids:   and  
The conductivity is the reciprocal value of the resistivity.
(The conductance is the reciprocal value of the measured resistance R)
6.2 Conductivity measurement
The conductivity measurement is a rather uncomplicated measurement. The standard electrodes are stable
for a long time if used correctly and can be adjusted by an integrated Cal-function.
Measuring ranges:
0.0 - 200.0 µS/cm
0 - 2000 µS/cm
0.00 - 20.0 mS/cm
0.0 - 200.0 mS/cm
If the range selection is set to „Auto Range“, the range with the best resolution is automatically selected. In
this case, the output value of the interface will always be the measured value with the highest possible
resolution (e.g. display value: 187.6 mS/cm interface output: 187600.0 µS/cm).
6.3 Resistivity measurement
The resistivity is the reciprocal value of the conductivity and the device displays it in kOhm•cm.
Measuring ranges:
0.000 - 2.000 kOhm*cm
0.00 –20.00 kOhm*cm
0.0 - 100.0 kOhm*cm
If the range selection is set to „Auto Range“, the range with the best resolution is automatically selected. In
this case, the output value of the interface will always be the measured value with the highest possible
resolution (e.g. display value: 18.76 kOhm*cm interface output: 18.760 kOhm*cm).
6.4 TDS measurement
At the TDS (total dissolved solids) measurement the filtrate dry residue is determined by means of the
conductivity and a conversion factor (C.tdS). Well suited for easy concentration measurements of e.g. salt
solutions. The determined value is displayed in mg/l.
Measuring ranges:
0.0 - 200.0 mg/l
0 –2000 mg/l
If the range selection is set to „Auto Range“, the range with the best resolution is automatically selected. In
this case, the output value of the interface will always be the measured value with the highest possible
resolution (e.g. display value: 1876 mg/l interface output: 1876.0 mg/l).
Displayed value TDS = conductivity [in µs/cm, nLF-temp. comp. at 25°C] •C.tdS (input at menu)
Approximately:
C.tdS
0.50
Monovalent salts with 2 ion types (NaCl, KCl, etc.)
0.50
Natural waters / surface waters, drinking water
0.65 - 0.70
e.g. salt concentration of aqueous fertilizer solutions
Attention: This are only approximate values –good for estimations, but no precise measurement.
For precise measurements the conversion value has to be determined for the corresponding solution for the
relevant concentration range.
This may be done by comparison with known reference solutions or by actually evaporating a certain amount
of solution with determined conductivity and subsequent weighing of the dry residue.
6.5 Salinity measurement
At the salinity measurement “SAL” the salinity (salt content) of seawater is determined (based on:
International Oceanographic Tables; IOT). Standard seawater has a salinity of 35 ‰ (35 g salt per 1 kg
seawater).
Commonly the measured value is displayed dimensionless in ‰ (g/kg).
Additionally the term “PSU” (Practical Salinity Unit) is sometimes used, the displayed value is the same.

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The salinity measurement has its “own” temperature compensation, i.e. the temperature is automatically
taken into account for the salinity measurement. The menu settings regarding the temperature compensation
are ignored.
The salt composition of the different seas is not the identical. Depending on place, weather,
tides, etc. there may be considerable divergences to the 35 ‰ according to IOT. Additionally
the salt composition may influence the ratio between salinity and actual salt content.
6.6 Electrodes / Measuring Cells
6.6.1 Design
Basically there are two types of measuring cells: 2-pole and 4-pole cells. The operation is done similarly; the
4-pole measuring cells can compensate polarization effects and –up to some degree –soiling due to its
complex measuring method.
2-pole measuring cell
4-pole measuring cell
6.6.2 Calibration / Adjustment of measuring cells
Especially in harsh environments and over long time the cell constants of measuring cells are drifting.
Depending on the application and use we recommend a regular checking of the precision of the measuring
chain: instrument + cell. For this there are control solutions available (GKL 100, 101, 102). At normal use a
checking each half year is recommended (see chapter 10 Automatic adjustment/calibration of cell
correction). A system check at the manufacturer is recommended in case of doubt: see chapter 12 Accuracy
Check / Adjustment Service).
6.7 Temperature compensation
The conductivity of aqueous solutions depends on its temperature. The temperature dependency is strongly
dependent on the type of solution. The temperature compensation recalculates solutions’ conductivity to a
consistent reference temperature. The most common reference temperature is 25 °C.
6.7.1 Temperature compensation “nLF” according to EN 27888
For most applications (e.g. in the area of fish farming, surface or drinking water measurements, etc.) the non-
linear temperature compensation for natural water (“nLF”, according to EN 27888) is sufficiently accurate.
The common reference temperature is 25 °C.
Recommended application range of nLF-compensation: between 60 µS/cm and 1000 µS/cm.
6.7.2 Linear temperature compensation and determination of temperature coefficient “t.Lin“
If the actual function needed for exact temperature compensation is not known, “linear temperature
compensation” is normally selected (Menu, t.Cor = Lin, t.Lin corresponds), i.e. one assumes that the
actual temperature dependency at the considered concentration range is approximately equal:
 
  
 󰇛  󰇜
Temperature coefficient of about 2.0 %/K are most common.
A temperature coefficient can be determined for example by measuring a solution with deactivated
temperature compensation at two different temperatures (T1 and T2).
 󰇛 󰇜
󰇛 󰇜
TKlin is the value input at the menu “t.Lin”.
LFT1 conductivity at temperature T1
LFT2 conductivity at temperature T2

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7 Configuration
Some menu points depend on current device settings.
To change device’s settings, press „Menu“ for 2 seconds. This will activate the configuration menu
(main display: “SEt”). Pressing „Menu“ changes between the menus points, pressing jumps to the
referring parameters, which can be selected with key .
The parameter value can be changed with or . Pressing „Menu“ again jumps back to the main
configuration menu and saves the settings. Pressing „Quit“ finishes the configuration.
Pressing “menu” and “store” at the same time for more than 2 seconds will reset the
device to factory defaults.
If no key is pressed for more than 2 minutes the configuration will be aborted. All changes will
be discarded!
Menu
Parameter
Value
Description
or
Set Configuration: General configuration
Input: Selection of measured variable
Cond
Conductivity
rESi
Resistivity
tdS
Total dissolved solids
SAL
Salinity
SEt
Change-over measured variables by Set-key
TDS measurement: conversion factor (only if Inp = tdS)
0.40 - 1.00
Conversion factor for TDS measurement
Cell Corr: Adjustment of cell correction: multiplication factor
0.800 -
1.200
Multiplication factor of cell correction
Factory setting: 1.000
Range: Selection of display range (conductivity, resistivity or tdS)
Auto
Automatic range selection
200.0 µS/cm
Lowest selectable range (conductivity)
…
…
400 mS/cm
Highest selectable range (conductivity)
Automatic adjustment/calibration with reference solution (only if Inp = Cond)
Edit
Manual adjustment to reference value
REF.S
Choice of standard reference solutions
REF.S: Choice of standard reference solutions for automatic adjustment/cal.
1413 µS/cm
Reference solution 0.01 M KCL
2760 µS/cm
0.02 M KCL
12.88 mS/cm
0.1 M KCL
50 mS/cm
Sea-water reference solution KCL
111.8 mS/cm
1 M KCL
Unit t: Selection of temperature unit
°C
All temperature values in degree Celsius
°F
All temperature values in degree Fahrenheit
Temperature compensation (not for InP = SAL)
oFF
No temperature compensation of conductivity measurement
nLF
Non-linear function for natural waters according to EN 27888
(ISO 7888), ground, surface and drinking water
Lin
Linear temperature compensation
Compensation coefficient (only if t.Cor = Lin)
0.300 3.000
Temperature compensation coefficient in %/K

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Menu
Parameter
Value
Description
or
Reference temperature of temperature compensation (only if t.Cor = Lin or nLF)
25 °C / 77 °F
Reference temperature 25 °C / 77 °F
20 °C / 68 °F
Reference temperature 20 °C / 68 °F
Adjustment/Calibration: Adjustment reminder period (factory setting: oFF)
1 …730
Adjustment reminder period (in days)
oFF
No adjustment reminder
Auto Hold: Automatic measuring value identification
on
Auto measuring value identification Auto Hold
oFF
Standard hold function on key press
Auto Power-Off : Selection of power-off delay
1...120
Power-off delay in minutes.
Device will be automatically switched off as soon as this time has
elapsed if no key is pressed/no interface communication takes place.
oFF
Automatic power-off function deactivated (continuous operation)
Set Output: Configuration of universal output
oFF
Output off -> minimal power consumption
SEr:
Serial interface activated
01,11..91
Base address for serial interface communication
Set Corr: Measurement correction
Zero point adjustment / offset of temperature measurement
oFF
No zero point adjustment for temperature measurement
-5.0 … 5.0°C
Offset of temperature measurement in °C
Slope adjustment of temperature measurement
oFF
No slope adjustment for temperature measurement
-5.00 … 5.00
Slope correction of temperature measurement in [%]
Set Clock: Setting of real time clock
HH:MM
Clock: set time hours:minutes
YYYY
Year: set year
TT.MM
Date: set date day.month
rEAd CAL: Read calibration data:
see chapter 11.2 Calibration storage (rEAd CAL)
8 Adjustment of temperature input
The temperature input can be adjusted with offset and scale. A reasonable adjustment presumes reliable
references (e.g. ice water, controlled precision water bath, etc.).
If the inputs are adjusted (i.e. offset and scale are different from default settings) the device will shortly
display “Corr” after turned on.
Default setting for offset and scale are ‘off’ = 0.0, i.e. inputs are not changed.
Zero point correction: Displayed value = measured value –OFFS
Zero point and slope correction: Displayed value = (measured value –OFFS) * (1 + SCAL / 100)
Displayed value °F = (meas. value °F - 32°F - OFFS) •(1 + SCAL / 100)
9 Real Time Clock (“CLOC”)
The real time clock is used for chronological assignment of the calibration points. Please check the settings
when necessary.
10 Automatic adjustment/calibration of cell correction
Besides the direct input of the cell correction (see below) via the menu (“CELL Corr”) the cell correction can
also be determined automatically: