Presentation; General Comments On Moisture In Materials; Description - Chauvin Arnoux PHYSICS line C.A 847 Notice De Fonctionnement

1. PRESENTATION

The C.A 847 moisture meter is designed to measure the level of moisture
in wood and construction materials such as plaster and roughcast, etc.
The measurement principal is as follows: an electric current is passed
through the two electrodes in order to measure the impedance variation
due to the moisture in the material. The instrument immediately translates
the measurement into a humidity %.
For wood, the instrument gives a direct reading of the level of moisture
in the wood, expressed as a % of H2O between 6% and 100%.
For other construction materials, the instrument determines the wood
moisture equivalent (WME).
2. GENERAL COMMENTS ON MOISTURE IN
MATERIALS
Moisture meters are generally calibrated for wood which is the
construction material with the best-known moisture levels, over and
above which the material starts to deteriorate.
In fact, under a level of around 16%, wood is considered dry and will not
deteriorate (no rot, retention of mechanical qualities, etc.).
Between around 16 and 19%, the acceptable amount of moisture is
reached and signs of deterioration may start to appear.
Finally, over and above 20%, the wood is considered to be damp and
signs of deterioration will obviously appear in time unless measures are
taken to reduce the level of moisture.
For other materials, a wood equivalence is used by establishing the
WME (wood moisture equivalent) which is the level of moisture reached
by wood, equal to that of the material being measured.
Interpretation of the measurement is facilitated since the threshold
percentage for transition from a "dry" to a "humid" condition is the same:
between 16 and 20%.

3. DESCRIPTION

See the Appendix in Chapter 8 at the end of operating instructions
1. Measurement prods to be inserted into the material
2. Protective cover (protects the prods and switches the instrument off)
3. "On" light which shows when the instrument is on or off
4. "Low batt" light, which indicates when the battery is low
5. 20 moisture level indicator lamps
6. Scale graduated as a % of moisture in wood or W.M.E., associated
with a coloured barchart that shows the difference between a dry
and humid condition
7. Lamp indicating a level of > 23%
8. When indicator lamp 7 is lit, you should press the red button to obtain
a correct reading
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