PCE INSTRUMENTS PCE-WMH3 (01) PDF Document

The standard Wood Moisture Meter PCE-WMH3 is equipped with 2 sets of needles ø 3.5 x 12 mm.

The following optional electrodes are available:

– needles ø 2.0 x 8 mm

– needles ø 2.5 x 10 mm

– veneer electrodes (no holes) (measuring range 6% to 20%)

Use the “WOOD TYPE” button to select the appropriate wood type group and the “WOOD TEMP.” button to set the wood temperature. The temperature setting step is 2°C. Pressing and holding the “WOOD TEMP.” button “fast forwards” the setting. This can be used to quickly change the temperature setting e.g. from -10°C to 40°C.

The most common European wood types are listed in a table on the instrument.

All exotic wood types (270 species) are divided into 4 groups. During measurements of moisture contents of exotic wood types the “WOOD TYPE” should be set to:

Group 1 – select 1

Group 2 – select 2

Group 3 – select 3

Group 4 – select 4

We recommend that the length of the needles you use should be about 25-30% of the thickness of the timber. With this length of needles the device displays the average moisture contents.

To conduct measurements:

– press and hold for a while the “ON/OFF” button to turn the instrument on,

– hammer the instrument into the wood, a line drawn between the needles should be perpendicular to the fibers (the resistance should be measured across the fibers),

– the strength used for hitting the wood should be appropriate to the hardness of the wood, do not use excess force, hitting the wood with the body of the device (when the needles have been completely inserted into the wood) may damage the device,

– wait until the result stabilizes,

– read the result on the LCD,

– the instrument can be turned off by pressing and holding the “ON/OFF” button or it will turn off automatically after approx. 5 minutes.

While conducting the measurements you should observe the following rules:

– Conduct the measurement no closer than 0.3 m from each end of the timber or in the middle, if the planks are shorter than 0.6 m.

– Choose the spots for measurements at random.

– Do not take the measurements where defects in the wood occur.

– Make 3 measurements on each side of the timber.

The measuring range of the Wood Moisture Meter PCE-WMH3 is 6% – 60% moisture contents. Moisture contents below 6% is indicated as “LO” on the LCD. All results over 60% are indicated as “HI”.

Measurements of moisture contents in a very dry wood (below 10%) are subject to interference. This can be observed when the result of the measurement becomes unstable. The sources of the interference are electrostatic charges and electromagnetic fields. Often the measurements of very dry wood are conducted in a very dry environment (below 30% RH) and this additionally increases the problem.

When measuring a very dry wood:

– do the measurements in a place where the electro-magnetic interference is minimal (away from electric engines, high voltage wires etc.),

– do not walk around the device,

– use thin needles because they provide a better contact with the wood,

– after inserting the needles, turn the device off and on again,

– place your hands on the wood to discharge any electrostatic charges,

– in extremely difficult conditions place the timber on a grounded metal plate or wire mesh.

The meter is equipped with an active power level control unit. When the power drops below an acceptable level a pulsating sign “BAT” appears on the LCD. This indicates that the battery has expired and should be replaced with a new one. To replace the battery:

– unscrew the plastic cork in the handle of the device (an internal spring will push the battery out),

– gently slide the battery compartment out of the handle (but no further),

– take out the old battery,

– put the new battery into the compartment (pay attention to correct polarization – minus towards the spring),

– push the battery compartment back in and screw the plastic cork back on.

(a) The most common cause of bending or breaking the needles is an incorrect way of pulling it out of the wood. To prevent the needles from bending (especially long needles in a hard wood) slide something (like a screwdriver) between the electrode and the wood.

(b) Every several hundred measurements check if the needles didn’t become loose. Loose needles bend or break more easily.

(c) When measuring a very thick timber you can use nails of appropriate length and ø1.5-2.5 mm. The distance between them should be 25 mm. A line drawn between them should be perpendicular to the fibers. Then touch the nail heads’ with the needles of the device, turn on the moisture meter and read the result.

(d) When measuring moisture contents in narrow pieces of wood you can do it along the fibers. For moisture contents over 20% the result will be a little bit higher than the real moisture contents. Results below 20% will not be noticeably influenced by the direction of the measurement.

(e) Pay special attention not to damage the LCD during the measurements.

(f) When a needle breaks use a small screwdriver to unscrew the broken part of the needle or remove the plastic part, unscrew the bolts with the springs and unscrew the broken needles from the inside.

Store the device in a chemically neutral atmosphere in temperature 5°C to 40°C and relative humidity 20% – 70% RH. If the electronic circuits become moist, dry the whole device. Unscrew the plastic part with the needles and heat the device up to 40-50°C (not more). The drying should last at least a few hours. For example you can put the device on a radiator.

Group 1 (set “WOOD TYPE” to 1)

Group 2 (set “WOOD TYPE” to 2)

Group 3 (set “WOOD TYPE” to 3)

Group 4 (set “WOOD TYPE” to 4)