Presentation; General Comments On Moisture In Materials; Description - Chauvin Arnoux C.A847 Notice De Fonctionnement

The CA847 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 construc-
tion 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 per-
centage for transition from a "dry" to a "humid" condition is the same:
between 16 and 20%.
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

1. PRESENTATION

3. DESCRIPTION

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