Symbols Used In The Display Of Cover - Elcometer protovale P330 Operating Instructions Manual

Symbols used in the display of cover

You will already have come across the use of the pair of equals ==
symbols used to indicate that the instrument has been zeroed and there
are some other symbols which may be shown. These are listed below
under the circumstances in which they may appear.
When the head is held well away from metal:
indicates that the instrument is correctly zeroed and will therefore
work to full accuracy;
indicates that the instrument is only approximately zeroed: cover
measurements to bars of known diameter will still be reliable for all except
the deepest bars, but the instrument should be zeroed correctly before
attempting to measure bars of unknown size or deeper-than-usual cover;
indicates that the instrument is not correctly zeroed.
appear after the first few minutes of warm-up time; but is more likely to be
a result of having previously zeroed the instrument while the head was
near some metal.
When the head is on the concrete surface (after being correctly
zeroed):
indicates that no metal is being detected;
may indicate that the concrete contains some ferrous aggregate;
but is more likely to mean that the presence of some metal has been
detected, but it is too far away for a meaningful cover measurement;
or
or 10mm or less respectively;
means that the instrument has calculated a cover of zero or less;
this only occurs under exceptional circumstances, such as telling the CM9
that the bars are 5mm diameter and then placing the head directly on a
50mm bar!
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indicate that (in these examples) the cover is 8mm or less
This may