H68.0.01.6C-06
Operating Manual GMK 100
page 9 of 14
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10
Plasterboard Measurement
Plasterboard is usually relatively slim (i.e. 12.5mm) -> select measuring depth 10mm.
Screws, cables and constructions behind the plasterboard (supporting stand) may falsify
the measurement.
11
Measurement of Other Materials
The device has not saved characteristics for all materials. But even if there is no characteristic
curve for your material you can do significant
relative measurements
.
We recommend the material
“rEF” (dimensionless digit-value, intentional no %u or %w display) 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 or %w) for this.
NOTE:
Please consider that the configuration of the measured wall (cavity block, cement joints,
reinforcements, etc.) may also influences the measuring values.
12
Additional Information to Moisture Measurement
12.1 Moisture u and water content w
Either moisture u or water content w is needed according to the application.
Carpenter, joiner, etc. normally use moisture u (relating to oven-dry mass)
Water content w is normally used for combustibles (i.e. wood briquette).
You can choose whether the device should use moisture or water content (p.r.t. chapter 13).
Moisture u (relating to oven-dry mass)
The unit is %u (also common: % atro, weight percent).
mass
wet
:
mass of the sample (= total mass = mass
water
+ 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%.
Water content w (= moisture relating to wet total mass)
The unit is %w
Example: 1kg wet wood that contains 500g water has a water content of 50%.
12.2 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.
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