EN
Operating manual – Material moisture measuring device T510
10
• The other typical error source to be considered is material
characteristics. This is particularly noticeable in case of high
moisture contents above the fibre saturation point (high con-
ductivity above 30 M%). Owing to the irregular cellular struc-
ture of various wood types and the i.a. resulting irregular
water retention within and outside of the cells, these meas-
ured values in part substantially deviate from the actual
moisture contents. It is, however, not possible to put a pre-
cise number on these deviations, even though the princi-
ple-related accuracies with 0.1 M% suggest a higher
accuracy than for the medium measuring range from 6 to 30
M%.
When looking at both error sources, one can conclude, that the
resistance measurement method is particularly well suited for the
determination of the moisture content between 6 and 30 M%.
Notes regarding the wood moisture measurement
• Make sure you have set the correct type of measurement
(wood).
• Make sure that the correct material code was selected.
• Prior to the actual measurement process, check the
temperature conditions. To do so, for instance a pyrometer is
to be used for measuring the surface temperature of the
wood type, which should then be compared with the wood
temperature set in the device. If both temperatures are
identical, measuring can be started.
If the wood temperature is higher than the value set in the
measuring device, a higher wood moisture than really there
will be displayed as a result.
• When measuring sawn timber, observe the instructions of
DIN EN 13183-2.
• Always insert the measuring tips transverse to the wood fibre
direction.
The conductivity transverse to the wood fibre direction is low-
er than that in line with it.
Depending on the type of wood it varies by the factor 2.3 to 8.
• When selecting the measuring positions observe the follow-
ing:
– Always measure the material moisture at three different
positions in order to achieve a sufficient accuracy by
means of the arithmetic average.
– Do not measure the face, because there are mainly dry ar-
eas.
– Preferably do not measure at cracks, branches or resin
pockets either.
• Oily and/or aqueous timber preservatives affect the measure-
ment result.
• If possible, do not measure wood with a temperature below
-5 °C. Too low wood temperatures distort the result of the
measurement.
• Avoid static charge of the material to be measured due to
friction. Static charge distorts the measurement result.
• With a wood moisture of less than 10 %, electrostatic forces
can appear at the good to be measured. This can falsify the
result of the measurement. Experience has shown that this
occurs at the outlet of veneer drying plants. Remove the stat-
ic charge by use of suitable grounding measures.
• The temperature value set within the device must be identical
to the wood temperature.
Example:
With a set temperature value of 20 °C and a wood tempera-
ture of 30 °C the measurement result would be distorted up-
wards by approx. 1.5 %.
• The measurement's accuracy depends on the contact pres-
sure of the measuring tips. The measuring tips must be con-
nected to the wood in a way that the contact resistance is
small as compared to the measuring resistance.
• The measurement results ought to be checked on a sample
basis by means of the Darr test.