22 PCM
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Operation Manual
Retest by taking small movements forwards or
backwards until the position is found where the
arrows just change direction, and the dB microvolt
reading is lowest. This will confirm the fault is directly
under the centre of the A-Frame.
Turn the A-Frame through 90 degrees so that it is now
across the pipeline.
Repeat previous stage. The fault point is now exactly
under the centre of the A-Frame.
Mark this point with a wooden stake or paint.
Continue along the pipeline section until all faults have
been found and marked.
7.3 Comparing Fault Severity
To determine the severity of the fault, and compare
different faults on the pipeline to decide repair priorities,
take the dB microvolt readings with the A-Frame at 90
degrees to the pipeline.
Place one of the A-Frame’s spikes directly above the
pipeline, and the other away from the pipeline. Start
approximately 1 meter from the fault position, testing at
25cm (or smaller) intervals. Note the highest dB microvolt
reading, or save it in the datalogger and note log number.
During the survey, you can switch to locating the pipeline
by pressing the function key and selecting the appropriate
locate frequency.
7.4 Saving PCM
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FF Readings
You can record and store up to one thousand A-Frame
results. Take readings at regular intervals, or write down
the distance between measurements and the log number.
To save readings keep the A-Frame in ground contact
and press the Antenna Select key. The direction arrow to
fault and the dBuV reading can be saved or rejected by
pressing the Up/Down arrow keys.
7.5 Data Upload – PCM
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FF Data
If you’ve established a link to your PDA – and you have
enabled Bluetooth – each log will be sent automatically
to your PDA when the reading has been ‘saved’.
Alternatively you can send the data to your PDA or
PC when the survey is complete.
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Figure 7.2: A-Frame Fault-Finding
Figure 7.3: Locating the fault
Figure 7.4: Taking a reading
Figure 7.5: Comparing fault severity
