Operating Instructions
for
Portable Moisture Meters
ETI 7000
ETI 7150
ETI 7200
Ref: 545-113 - 20.4.10
WOOD REFERENCE TABLE
Wood 1
Wood 2
Afara Ayan
Ash; European, Japanese
Beech; European
Balsa
Blackbutt
Banga Wanga
Camphorwood
Boxwood
Cedar; Western Red
Cyprus Chestnut
Dahoma Danta
Fir; Grand
Greenheart
Gum; American Red, Spotted
Hemlock
Gurjun Jarra
Kapur
Larch; European, Japanese
Kuroka Missanda
Maple; Pacific, Rock, Sugar
Niangon
Myrtle
Oak; Tasmanian
Oak; American Red & White
Pine; American Long Leaf
Oak; European, Japanese
Pine; Sugar, Pitch
Padang Sapele
Pine; Scots, Yellow
Spruce
Poplar; Black
Walnut; European
Redwood; European
Whitewood
Walnut; American
Yew
For a more extensive list of timbers and average moisture %age correction,
please contact the ETI Sales Office.
GUIDANCE NOTES
ETI moisture meters measure the electrical resistance of a material and provide an
indication of the moisture content of wood and the Wood-Moisture-Equivalent (WME) in
materials other than wood. Readings indicate a dampness condition of approximately the
same significance in wood, plaster, brick etc., even though the actual moisture content
will be different. A change from green to red on the scale shows that further tests are
appropriate. Problems arise from the 'structure' of the material being tested, the presence
of other conductive material that may affect the reading, and also the correct method of
testing. Factors that may effect readings include:
4
Density of the material - this is important when interpreting the moisture content that
is acceptable in a particular material. Even the 'same' material will be variable in
composition from one example to another.
4
Ability to absorb moisture - materials will have different capabilities to hold moisture
in a satisfactory state.
4
Conductivity of substance - most materials have an inherent conductivity even if this
may be negligible. Conductivity may be affected by carbonaceous or ferrous material
content.
4
Purity of free water - the conductivity of water varies with it's purity.
4
Surface treatment - certain surface treatments may be conductive. Residues may
contain carbonaceous material or have a misleadingly high moisture content. Wood
treatments of a salts based liquid will also effect conductivity.
4
Temperature - the electrical resistance at any given moisture content increases as the
temperature decreases.
4
Timber grain - due to the cellular structure of timber, readings will be less accurate
taken in the end grain.
4
Timber adhesive - composite materials such as plywood will give artificially high
readings due to adhesive content.
4
Homogeneity - different densities in a material, such as knots in wood will produce
erroneous results.
4
Electrical contact - it is important to maintain good contact between the pins and the
measured substance. Hard surfaces may require 1.2 mm diameter holes to be drilled.
4
Moisture gradient - the moisture content of a material may vary across it's section due
to various factors.
As a general rule of good practice, results should be obtained from different areas of
the material. If in any doubt then the (Oven Dry) test method should be used. A linear
scale is provided for relative measurement, therefore, facilitating the comparison of
unknown moisture measurements against known standards obtained by the (Oven Dry)
test method, i.e.:
Original Weight - Oven Dry Weight
Oven Dry Weight
Testing and calibration of ETI moisture meters is carried out using electrical resistance as
the basis for measurement. Standard resistance values are verified by empirical testing
in accordance with OIML R 92. Wood moisture meters - verification methods and
equipment: general provisions, issued by Organisation Internationale De Métrologie
Légale, - 1989.
In conclusion, it must be reiterated that the meter reading is only a guide as to the
'dampness' of the material under test. Knowing the actual moisture content does not
indicate whether that material is 'dry' or 'wet'.
x 100 = %age Moisture Content = U
Serial No. ______________________________________________
Tested by _______________________________________________
Date ___________________________________________________
manufactured by
Electronic Temperature Instruments Ltd
tel: 01903 202151 · e-mail: [email protected] · www.etiltd.com