User manual
H60.0.11.6C-16 Operating Manual GMH 3830 Page 8 of 18
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5.5 Measuring In Wood: Measuring With Two Measuring-Needles
Normally wood is measured with measuring-needles. Used electrodes: impact-electrode GSE91 or GSG91,
reciprocating piston electrode GHE91. For measuring wood, punch in the measuring-needles across to the wood-grain,
having a good contact between the needles and the wood (measuring along wood-grain deviates minimal)
Select correct wood-sort (refer to Appendix A).
Ensure measuring the correct temperature.(refer to 5.4)
Hint: The special GTF38 temperature-probe can be stuck into a hole punched in with the
electrode before (see picture on left).Now read the measuring-value or when having
activated the auto-hold-function initiate a new measuring by pressing Store/ (button 6) .
The measured resistance will be extremely high when measuring dry wood (<15%) thus
the measuring will need more time to achieve its final value. Among other things static
discharge could momentarily falsify the measuring. Therefore beware of static discharge
and wait long enough until a stable measuring value is displayed (unstable: „%“ blinking)
or use the auto-hold-function (see chapter 5.3 Auto-Hold Function).
Most accurate measurements can be carried out within the range of 6 to 30%.
Beyond this range the acquirable accuracy will lessen, but the device will deliver
reference values still sufficient for the practitioner.
Reciprocating piston
electrode GHE91 with
temperature-probe GTF38
It is measured between the measuring-needles insulated among each other. Requirements for an exact measurement:
- choose right correct place to measure: place should be free of irregularities like resin–clusters, knurls, rifts, etc.
- choose correct depth: Recommendation for trimmed timber: punch in the needles up to 1/3 of the material
thickness.
- Perform multiple measurements: the more measurements will be averaged, the more exact the result will be.
- Pay attention to temperature-compensation: the temperature-probe should be measuring the temperature of the
moisture-measuring-place when measuring with external temperature-probe (Atc on).
Without temperature-probe: let the device adapt to the temperature of the wood (Act on) or enter the exact
temperature manually (Act off).
Frequent sources of errors:
- Attention with oven-dried wood: the moisture dispersion may be irregular, often in the core is more moisture than on
the edge.
- Surface-moisture: The wood-edge could be more humid than the core if the wood had been stored outside and e.g.
was in rain.
- Wood preservative and other treatment could falsify the measuring.
- Fouling at the connections and round the needles could result in erroneous measurement, especially with dry wood.
5.6 Measuring Other Materials
5.6.1 ‘Hard‘ Materials (concrete or similar): Measuring with brush-type probes (GBSL91 or GBSK91)
Drill two holes with Ø6mm (GBSK91) or Ø 8mm (GBSL91) at intervals of 8 to
10cm into the material to be measured. Do not use edgeless drills: the
resulting heat will evaporate the moisture which will result in faulty measures.
Wait for at least 10min, blow out the holes to clean them from dust. Apply
conductivity compound on the brush-type probes and stick them into the holes.
Choose correct material (see Appendix B: Additional materials), read the
measuring value. Observe that the holes dry out by-and-by, and the device will
measure a value too low, if you want to use them several times.
This effect can be compensated by using conductivity compound: insert
profuse conductivity compound between the holes and the brush-type probe,
and let the electrode stick in the hole for about 30min before measuring (with
the device switched off ). Temperature-compensation plays no role when using
the building material measuring.
with brush probe GBSL91
5.6.2 ‘Soft‘ Materials (polystyrene or similar): Measuring with Measuring-rods or -pins (GMS 300/91)
Useable electrodes: impact electrode GSE91 or GSG91, reciprocating piston electrode GHE91.
Procedure as described in chapter measuring in wood.
5.6.3 Measuring bulk cargo, bales and other special measures
Usable probes e.g. injection probe GSF 40, GSF 50 (GSF 38) or measuring rods GMS 300/91 mounted on
GSE91 or GSG91.
Measuring of splints, wood chips, insulating material and similar – GSF 40 / GSF 50:
When using injection probes or measuring pins oscillating movements have to be avoided when pushing in the
probes. Otherwise hollows between the probes and the material may falsify the measuring. The material should
be sufficiently compressed. When in doubt repeat the measuring a few times: the highest measuring value is the
most exact one. Especially when using the injection probe pay attention having a foulness-free plastic insulator
(situated immediately underneath the measuring-needle).
Measuring bale of straw and hay bale – GSF 40 (GSF 38/50): Always inject the electrodes form the plain side
of the bale, never from the round side, the probe can be inserted much more slightly, esp. when using GSF 38/50.