Search Heads - Elcometer 331 Operating Instructions Manual

5
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Borehole
Probe
The Borehole Probe is used
to locate reinforcement bars, tendon ducts and other metallic objects
in the
vicinity
of holes
drilled
into
concrete The probe will
also measure depth of cover
over
a limited
range, making
it
ideal when
attempting
to
drill through
a
structure
without making contact with
reinforcementbarsortendonducts TheBoreholeProbeisavailableintwolengths; 400mm(16")
and 1000 mm
(40")
The Borehole Probe has two search fields; forwards looking and sideways looking. Readings
can
be
taken looking forward from the end
of
the probe or looking sideways (at right angles
to
the axis
of
the probe) - Figure 19
A
switchq
on the handle controls which search field
is active
Figure
19.
Borehole probe search fields
The body of the probe has a scale marked every
10
mm (0 5") along its
length
Use this scale to
measure the depth
of
reinforcement bars located
to
one side of the
hole
The scale
indicates
distance from the centre
of
the sideways looking sensor
in the
probe
To measure the depth
of
the
borehole,
add
15
mm (0 6") to the reading taken from the scale
The sideways looking search field is located on the
side of
the
Borehole Probe marked with the
scate
To
scan
for
reinforcement bars
to the side of the
borehole: Set the
switch
to the
sideways
looking position and
move
the Borehole Probe
into the drilled hole, slowly rotating the
probe
through
360' (Figure 20 overleaf)
q
\Menever
the position of the switch
is changed, the Covermeter must be zeroed
zo