GREISINGER GMI 15 plus User manual

H68.0.03.6C-02
GHM GROUP - Greisinger
GHM Messtechnik GmbH | Hans-Sachs-Str. 26 | 93128 Regenstauf | GERMANY
Tel.: [phone] | [e-mail] | www.greisinger.de
Operating Manual
Capacitive moisture indicator
for non-destructive measurement
as of version 1.2
GMI 15 plus

Please carefully read these
instructions before use!
WEEE-Reg.-Nr. DE 93889386

Please consider the safety instructions!

Please keep for future reference!
For non-destructive measurement

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Index
1GENERAL NOTE .......................................................................................................................................3
2SAFETY........................................................................................................................................................3
2.1 INTENDED USE.........................................................................................................................................3
2.2 SAFETY SIGNS AND SYMBOLS...................................................................................................................3
2.3 REASONABLY FORESEEABLE MISUSE........................................................................................................4
2.4 SAFETY GUIDELINES.................................................................................................................................4
3PRODUCT DESCRIPTION.......................................................................................................................4
3.1 SCOPE OF SUPPLY.....................................................................................................................................4
3.2 OPERATION AND MAINTENANCE ADVICE..................................................................................................4
4DISPLAY AND CONTROL ELEMENTS................................................................................................5
4.1 DISPLAY ELEMENTS .................................................................................................................................5
4.2 CONTROL ELEMENTS................................................................................................................................5
4.3 MEASURING SPOT:REAR SIDE ..................................................................................................................5
5START OF OPERATION ..........................................................................................................................5
6MEASUREMENT BASICS........................................................................................................................6
6.1 MEASURING FIELD &DEPTH ....................................................................................................................6
6.2 MOISTURE RATING (‘WET’ -‘MEDIUM’ -‘DRY’).............................................................................6
6.3 HOLD THE DEVICE....................................................................................................................................7
6.4 CHARACTERISTICS AND MATERIALS.........................................................................................................7
6.5 ZEROING FUNCTION..................................................................................................................................7
7WOOD MEASURING ................................................................................................................................8
8FLOOR SCREED MEASUREMENT.......................................................................................................8
9MEASUREMENT OF OTHER MATERIALS........................................................................................8
10 ADDITIONAL INFORMATION TO MOISTURE MEASUREMENT.............................................9
10.1 MOISTURE U.........................................................................................................................................9
10.2 CM-MOISTURE...................................................................................................................................10
11 ADJUSTMENT ......................................................................................................................................10
12 ACCURACY INSPECTION: ADJUSTMENT /UPDATE SERVICE..............................................11
13 ERROR AND SYSTEM MESSAGES..................................................................................................11
14 DISPOSAL..............................................................................................................................................11
15 TECHNICAL DATA..............................................................................................................................12
ADDENDUM A: WOOD TYPES TABLE ....................................................................................................12

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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 measurements of moisture (%u) of materials with flat surface and a
thickness of at least 10mm.
The measurement takes place at an insulated measuring spot at the rear side of the device.
Applicable for:
wood
concrete
etc.
The device must be used only according to its intended purpose and under suitable conditions.
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.
Use the device carefully and according to its technical data (do not throw it, strike it, …)
Protect the device from dirt.
2.2 Safety signs and symbols
Warnings are labeled 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.

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2.3 Reasonably foreseeable misuse
This device must not be used at potentially explosive areas!
The device must not be used at a patient for diagnosis or any other medical purpose!
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.
Any failure to comply with these instructions could result in death, serious injury and material
damage.
The measuring principle implies that both water and metal are influencing the display value.
Eventually existing metal structures may have negative effect to the measuring, please consider the
Measurement Basics (chapter 6).
2.4 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.
3 Product Description
3.1 Scope of supply
The scope of supply includes:
GMI 15 plus
9V - battery
Operating manual
Test protocol
3.2 Operation and maintenance advice
Battery powered supply
If ‘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.
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.

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4 Display and Control Elements
4.1 Display elements
1: Main display
Display of the current moisture or water
content
2: Material display
The name of the selected material
characteristic curve is displayed.
3: Moisture rating
Moisture rating via bar graph.
4: HLD
The measuring value is ‘frozen‘ (hold-key)
4.2 Control elements
Key 1:
on/off key,
Press long: switch device off
Key 2:
sort up
Material selection: upwards, p.r.t. chapter 6.4
Key 3:
hold:
press shortly: The measuring current value is ‚frozen‘ (hold-
function), ‘HLD’ is displayed
press for 2sec.: Zeroing function (p.r.t. chapter 6.5)
Key 2 and 3
together:
sort down
Material selection: downwards, p.r.t. chapter 6.4
4.3 Measuring spot: rear side
The entire grey surface has to lie on the measured material
without any air gap.
The area “25 mm” (grey) mark the area under that it is
predominantly measured.
5 Start of Operation
Switch the device on with the key .
After segment test the device displays some information to its configuration:
S.25 if a slope adjustment has been made (p.r.t. chapter 11)
The device is ready for measuring afterwards.

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6 Measurement Basics
6.1 Measuring field & depth
The device measures with an electric field (capacitive measuring method), which propagates from
the rear side downwards. The measuring depth can be changed between approx. 10 mm and 25
mm with the sliding switch.
Side view: measuring field and penetration depth for “25 mm”
The specifications for the penetration 25 mm are just approximate values. The actual depth will be
the higher the wetter the measured material is. Therefore areas deeper than 25 mm will be
measured in very wet materials.
On the rear side the area is marked under that it is predominantly measured.
For precise measurements, the device has to lie on the measured material not only at
the marked measuring spot but at its whole rear side. If there is an air gap between
device and material the measured value will be too dry.
Here are some examples for measurements that are not precise at all. (Measured value too dry in
all cases):
False: wrinkled surface (extreme
example!)
False: unsteady surface
False: material too thin
6.2 Moisture rating (‘WET’ -‘MEDIUM’ -‘DRY’)
In addition to the measuring value there is a moisture rating via bar graph. For most applications,
the decision ‘wet or dry’ is easy and comfortable and has no longer be deduced from literature and
tables.
However, this rating can only be a first approximate value, because factors like the application field
of the measured material have to be taken into account for the final rating. This device cannot
completely replace the knowledge of an experienced craftsman or technical expert.

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6.3 Hold the device
The water content of the hand has an impact on the measuring value, if the device is held
inappropriately.
The best results will be obtained if you lay the device down or hold it the way as shown in picture 3.
Picture 1: Held in a wrong way!
Picture 2: laid down –right!
Picture 3: Held in the right way!
6.4 Characteristics and materials
Material
rEF
Reference characteristics
HoL
Wood, density = 550 kg/m3
bEt
Concrete (density ≈ca. 2.2 to/m3)
In the appendix there is a table with the assignment of which wood species correspond to the
specified density. Other types of wood can also be measured, but a higher deviation than specified
is to be expected.
The materials are selected with these keys:
material selection upwards: press
Material selection downwards: press at the same time
The use of inappropriate characteristics can cause faulty measurements!
The device is an indicator, not a precision measuring device. More accurate
measuring can be obtained with the GMK 100 or GMK 210 devices with more
selectable characteristic curves.
6.5 Zeroing function It is recommended to run regularly the zeroing function
for best measuring results:
Hold the device in the air as shown in the left picture
and press key “hold” for 2 seconds.
You can easily see whether the zero point is ok with
the “rEF” characteristics. If the device shows at air a
value <0.5 or >0.5 or “Er.4” with “rEF” characteristics
you have to run the zeroing function.
Please pay attention not to influence the
zeroing function with your hands. The
best way to ensure this is shown left.

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7 Wood Measuring
Best results are obtained if you measure crossways to the wood’s grain. (see right picture)
Unplaned and wrinkled surfaces are causing too low measuring results!
NOTE: Wood is a natural product. Its density fluctuates due to the tree’s
growth and flaws (knots, cracks, resin pockets, etc.). This may lead
to measuring errors up to several %u, because the measurement
depends on density.
If your kind of wood is not listed in addendum A, it can be measured, but an
increased measurement error must be expected.
8 Floor screed Measurement
NOTE: Floor screed dries patchy and therefore areas may be differently wet. A big amount of
water has to be released upwards (evaporate) before you can tile it. The floor screed has
to be drier if a vapor-tight covering should be used as if it would be with a diffusion
permeable covering. Therefore the moisture rating of the device can only be a first
approximate value and the decision whether the floor is ready for further covering or not
cannot be based only on this rating.
Reinforcements (iron) or floor heating near the surface may cause erroneous measuring
results. Please consider chapter 10.2 CM-moisture.
9 Measurement of Other Materials
Should other material than screed or wood be measured, you can do significant relative
measurements.
We recommend the material “rEF” (dimensionless digit-value) for this purpose.
For example if you want to evaluate water damage you can measure surely dry spot and an
evidently wet one (identifiable by salt efflorescence, water spots, mould growth, etc.). Then you can
compare the other measuring values with them and get the moisture distribution of your measuring
area or find the reason for the moisture penetration.
You do not need absolute values (%u) for this.
NOTE: Please consider that the configuration of the measured wall (cavity block, cement joints,
reinforcements, etc.) may also influences the measuring values.

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10 Additional Information to Moisture Measurement
10.1 Moisture u
The displayed material moisture is the most common measuring unit for material moisture
measuring (relating to oven-dry mass)
Water content w is normally used for combustibles (i.e. wood briquette).
Moisture u (relating to oven-dry mass)
The unit is %u (also common: % atro, weight percent).
mass wet: mass of the sample (= total mass = masswater + mass dry)
mass water: mass of the water contained in the sample
mass dry: mass of the oven-dried sample after (water has been evaporated)
Example: 1kg wet wood that contains 500g water has a moisture u of 100%.
In rare cases Water content w is used
Example:
1kg wet wood that
contains 500g water has
a water content of 50%.
moisture u[%] = ( (mass wet - mass dry ) / mass dry) *100
or: moisture u[%] = (mass water / mass dry) *100
water content [%] = ( (mass wet - mass dry) / mass wet) *100
or: water content [%] = (mass water / mass wet) *100

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10.2 CM-Moisture
The CM-moisture (unit [CM%]) is often used for materials like floor screed. This moisture rating is
correlated to the moisture u: it is calculated by the same equations. It is measured by the CM-
method (destructive testing with high complexity). It is the only accredited measuring method
(besides the time-consuming oven-dry method) for floor screed measurements in Germany.
The values measured with CM-method
and oven-dry method (%u) may differ for
some materials. Especially for building
materials containing cement CM-
measurements will always get lower
values than oven-dry measurements.
The conversion is material-dependent,
because the differences between both
values depend on the used product.
The conversion shown in the left picture
is a practicable approximation.
For gypsum, gypsum plaster and anhydrite screed the value %u equals approximately the CM-
value.
11 Adjustment
The accuracy can be checked with the testing probe PW 25 (optional accessories).
Select the material “rEF” and run the zeroing function (p.r.t. chapter 6.5).
Lay the device onto the testing cube. If the device displays a different value than the value printed
on the cube for the GMI 15, you can use the slope correction to adjust the device:
Displayed value rEF =(measured value rEF * (1 + slope correction / 100 )
Follow these instructions to adjust the device:
Switch the device off.
Press and keep it pressed, while turning the device on (press shortly).
Release the hold-button not before the first parameter “S. 25” is displayed.
Set parameter with up or down .
Jump to the next parameter by pressing .
Parameter
Value
Information
button
buttons
Slope correction for measuring factory setting: of= 0%
OF
-19 … +19
Value of slope correction in %
Press again to store changed settings, the device restarts (segment test).
NOTE: If there is no key pressed within the menu mode within 2 minutes, the configuration will
be cancelled, the entered settings are lost!
0
1
2
3
4
5
1234567
CM-%
% u
conversion [% u] to [CM-%]
for concrete and cement screeds

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12 Accuracy Inspection: Adjustment /Update Service
You can send the device to the manufacture or retailer for adjustment and inspection.
Moreover the manufacturer can do the latest software update. This ensures that future
improvements are provided to owners of older devices in a cost-saving way. You can display the
current software version if you do not release the on/off button after you switched the device on, but
hold it for more than 5 seconds. (i.e. “r. 1.0”)
13 Error and System Messages
ER. 1
Value exceeding measuring range, value too high
ER. 4
Value below display range
ER. 7
System error –the device has detected a system error (device defective or not
within working temperature)
The blinking bAt display indicates low battery voltage, device will continue to work
for a short time.
The battery is consumed and has to be changed. Measurements are no longer
possible.
14 Disposal
Separation by material and recycling of device components and packaging must take place at the
time of disposal. The valid regional statutory regulations and directives applicable at the time must
be observed.
NOTE
The device must not be disposed of with household waste. Return it to us, freight prepaid. We
will then arrange for the proper and environmentally-friendly disposal.
Private end users in Germany have the possibility of dropping off the device at the municipal
collection center. Batteries must be removed beforehand!
Please dispose of empty batteries at the collection points intended for this purpose.

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15 Technical Data
Measurement
Method
Capacitive (=dielectric) measuring method, non-destructive
Depth
approx. 25 mm
Materials
curves for wood and screed, additionally reference curve for high-
resolution relative measurements
Resolution
0.1 %; for more than 19.9 %: 1 % (%u)
Range
Material moisture (u): 0.0 … 100% (wood), 0.0…~8.0 (concrete)
Moisture rating
Display: Rating of the moisture in 6 levels from WET to DRY
Accuracy
The achievable accuracy depends significantly on the application and
the properties of the measured material!
Display
2 displays for material and measured value
Hold function
Press button to freeze current value.
Working temperature
-5 to 50 °C; 0 to 80 % RH (non condensing)
Storage temperature
-25 to 70 °C
Power supply
9 V-battery type IEC 6F22 (included)
Power consumption
(measurement)
Approx. 0.12 mA (battery life time: more than 2500 hours for alkaline
battery)
Used battery display
“bAt” displayed if battery used, warning: “bAt” blinking
Auto off-function
Device will be automatically switched off after 120min if not operated
for longer time
Housing
impact-resistant ABS plastic housing, front side IP65
Dimension
Approx. 106 x 67 x 30 mm (H x W x D)
Weight
Approx. 145 g incl. battery
Directives and standards:
The instruments confirm to following European Directives:
2014/30/EU EMC Directive
2011/65/EU RoHS
Applied harmonized standards:
EN 61326-1 : 2013 emissions level: class B
emi immunity according to table A.1
Additional fault: <1%
EN IEC 63000:2018
Addendum A: Wood types table
english
lat.
charact.
Bossè
Guarea cedrata
HoL
Cedar, White
Melia azedarach
HoL
Cherry, Wild-
Prunus avium
HoL
Larch, European-
Larix decidua
HoL
Larch, Japanese-
Larix kaempferi
HoL
Larch, Western-
Larix occidentalis
HoL
Maple, New Guinea
Flindersia pimentelianan
HoL
english
lat.
charact.
Maple, Sycamore-
Acer pseudoplatanus
HoL
Meranti, White-
Shorea hypochra
HoL
Meranti, Yellow-
Shorea multiflora
HoL
Pine, European Black-
Pinus nigra
HoL
Rosewood, N. Guinea
Pterocarpus indicus
HoL
Tiama
Entandrophr. angolense
HoL
For not listed woods, larger deviations are to be expected.