RDM-3P v.1.0 - PAPER MOISTURE METER
ADDENDUM
This addendum is to be used in conjunction with the Owner’s Manual for the
RDM3 Wood Moisture Meter. The Owner’s Manual details the various functions of the
RDM3 meter, including the optional PC interface. This addendum contains information
specific to the paper, paper core, baled paper and corrugated applications. We
recommend the user read the Owner’s Manual and addendum completely, before
using the RDM3-P.
Changes to the RDM-3 Wood Moisture Meter that are reflected in the RDM3-P include:
All wood species have been deleted from the meter and replaced by 3 scales for
the paper applications. PAPER (5.3%-23%), RELATIVE (0-100) scale, and
BALED PAPER (8%-40%). NOTE: Displayed readings outside of this nominal
range should be taken as a “no reading”. They are included in statistical
calculations to provide a more complete profile of the moisture distribution.
The wood temperature compensation feature has been eliminated.
TESTING PAPER, PAPER CORES, AND CORRUGATED PRODUCTS
Set the meter scale for PAPER. Check that the contact pins are firmly hand
tightened.
Push the contact pins into the paper product to their full penetration if possible.
Press the SELECT button to read %MC when in TRIGGER mode. In CONTINUOUS
mode, press SELECT to start readings and press SELECT again to store a reading.
Since the readings are the result of an “average” calibration, if a high degree of accuracy
is required, the meter should be checked on the specific material and corrections
determined by the user.
Meter readings indicate moisture content of material under test at room temperature of
approx. 70º F/21°C Meter readings will be affected by lower or higher temperatures.
Lower temperatures cause readings to be higher than actual MC; higher temperatures
cause readings to be lower than actual MC. If a temperature correction is desired, the
attached Temperature Correction Table may be used as a guideline.
1
The meter tends to read the highest moisture content that is in contact with both pins. If
thick samples are not well equalized, it may be necessary to make tests at different
depths to determine the degree of uniformity of moisture distribution in the sample.
If the meter is used on stock so thin that the full length of the pins is not entirely
embedded in the thickness of the sample, the readings tend to indicate a lower than
actual MC. This can be overcome by testing more than one sample in stacks.
USING THE 0 –100 RELATIVE SCALE
This scale is used to test the moisture content of hygroscopic materials for which a
calibration is not available. Depending on the material, a special application external
electrode, instead of the integral contact pins may be required. Increasing readings on
the 0-100 reference scale indicate higher levels of moisture content. These readings can
be translated into percent moisture content once a calibration has been developed.
Set the meter scale to REL 0-100. If necessary, attach an external electrode to the
meter.
Push the contact pins into the material or apply the external electrode.
Take readings as described above.
The readings may also be used for comparative tests, after meter readings have been
related to given conditions for the materials involved. When the meter is used as a
gauge for comparative tests, readings should be taken on samples considered to be at
“safe’ levels or in satisfactory condition. These readings are then used as the “standard”
against which subsequent readings on the same material are evaluated.
The “standard” for any given material is related to safe storability or any other property
which is important for further production processing.
TESTING BALED SCRAP PAPER
Set the meter scale to BALED PAPER. Attach an external electrode to the meter.
Push the external electrode into the material being tested.
Take readings as described above.
2
The level of accuracy of meter readings depends on a number of factors: similarity
between the material tested and samples on which the calibration was made; moisture
distribution; and chemical application or processing which may affect the electrical
properties of the paper product.
The required electrode is the H-4 with a #830-series prod. (10”or 18”). A sharp, steel rod
to open the hole for the prod may be helpful if the bale is very dense.
A few meter readings in a limited number of specific areas of a large mass can hardly be
projected to indicate an average moisture content of an entire bale. The readings can be
very helpful in providing an indication of the overall moisture condition inside the bale
and to detect areas of excessive moisture.
Meter readings may be used as an arbitrary guideline in determining whether or not to
accept or reject the material. Since checking the moisture condition of bales is
performed when buying and selling, the specific value of the meter readings remains an
element to be agreed upon between buyer and seller. Such an agreement should
consider not only a specific “range” of readings, but the number and location of where
they are taken.
The following ranges can be used as a guideline and may help to interpret the readings:
Readings of 8%-12%, with EMC to 60% RH are usually considered “dry”.
Readings from 12%-20% with EMC to 95% are usually considered “acceptable” but
should be taken with some reservation.
Readings of 20%-40% are considered “wet” and unacceptable.
METER CALIBRATION CHECK
When using the MCS-2 external standard to check the meter’s calibration, the RDM-3P
meter should be set to the PAPER scale and indicate 6.2% and 9.6% +/-0.2. If the meter
reads out of tolerance, replace the battery with a fresh one. If the meter is still out of
tolerance, return it to Delmhorst per website instructions.
Delmhorst Instrument Co.
Towaco, NJ 07082
973-334-2557
info@delmhorst.com
www.delmhorst.com
Rev 01/2017
3
WOOD TEMPERATURE
CORRECTION TABLE
METER READINGS
°C
°F
6 7
10
15
20
25
30
35
40
50
60
-20 0 9 11
15
22
31
38
45
53
-10
20 8
10
14
20
28
34
40
47
55
5
40 7 8 12
18
24
30
36
42
48
15
60 6 7 11
16
21
27
32
38
43
54
30
80 6 7 9
14
19
23
28
33
38
47
55
40
100 5 6 8
12
17
21
25
29
34
42
50
50
120 5 5 7
11
15
19
22
26
30
38
44
60
140 4 5 7
10
14
17
20
23
27
34
40
70
160 4 4 6 9 12
15
18
21
24
30
36
80
180 3 4 5 8 11
13
16
19
22
27
33
95
200 3 4 5 7 10
12
14
17
19
24
28
105
220 2 3 4 6 9
11
13
15
17
21
26
Moisture content values shown shaded are only qualitative, since they are above the
fiber saturation point in wood.
The temperature correction values shown in this chart have been rounded for easy
reference.
The chart may also be used as a guideline for PAPER applications where processing
temperatures are outside of the range of 50F-90F/10C – 30C range and a temperature
correction is desired.
Delmhorst Instrument Co
Towaco, NJ 07082
973-334-2557
info@delmhorst.com
www.delmhorst.com Rev.01-2017
4
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