Delmhorst Instrument Navigator - Manual (Page 22)

Copyright
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2007, Delmhorst Instrument Co.
Page 22 of 28
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Set the meter’s parameters as described previously in the owners’ manual. If the species
(construction-grade only) is unknown, set the meter to the reference calibration, Douglas Fir
and take the readings at face value.
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To take a reading, align the contact pins parallel to the grain and push them to their full
penetration into the wood, if possible. Insulated pins read only at the tip and can be driven to
the desired depth.
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Press the SELECT button and read the moisture content on the meter scale. The meter
displays the %MC for two seconds.
NOTE: MC RANGE AND VALID READINGS
Readings below 5% or above 60% are displayed as LOW or HIGH, respectively. However, since
the resistance of the wood also depends on the species and temperature of the wood, the meter
may not always be able to read down to 5%. For different species and different wood
temperatures, there is a minimum %MC limit below that the meter can not read. All readings
below this “lowest limit” are displayed as LOW, and are not stored. These readings are not
considered valid readings and are not used by the meter in any statistical calculations.
USING 0-100 NUMERICAL REFERENCE SCALE (REL 0-100)
When taking a reading on hard materials such as concrete or masonry, set the meter to REL 0-
100 for a qualitative indication of the moisture level.
Make the best use of reference scale by first establishing a benchmark for the material you are
testing. Take readings in areas that you know are dry, or acceptable. Then take readings on
areas that are wet. These “dry to wet” readings can be used as reference points against which
subsequent readings are compared. Understanding the meter’s behavior on a particular material,
along with these comparative readings, your experience, and visual clues will all help determine
the overall condition. All readings should be evaluated in the light of factors such as type of paint,
type of construction, and climatic conditions.
The user-selectable alarm will sound if the displayed reading is above the alarm value.
TESTING CONCRETE SLABS:
Moisture meters are an effective tool to check moisture in concrete. They can tell you where there
may be excess moisture and help determine if you need to conduct further testing.
It is important to test both the surface and mid-section of the slab, especially if the slab is on or
below grade. This will help determine if there is continuous moisture migration toward the
surface. If this condition exists, the moisture movement may be so slow that once it reaches the
surface, moisture evaporates and causes a “dry” reading when a surface test is made.
However, if a sub-surface test is made, the meter may read “wet” indicating the presence of
moisture. When the slab is covered and the upward movement of moisture continues, moisture