4 Locating
Page 22 of 33
the depth screen to “time out” or momentarily press the on/off key which will return the vScan to the
locate screen.
8.
Now push the Sonde in a couple of meters and repeat the above to mark out the route of the pipe or
duct. Keep the insertion intervals small (2 to 3m) so as to ensure the Sonde is not lost.
4.7
Advanced Locating Techniques
4.7.1
Two Person Sweep
This is an Induction method technique and is used to quickly check an area for any metallic services.
Method:
1.
Select the area to be checked. One person holds the transmitter and the other holds the vScan receiver.
2.
Attach the carry strap to the transmitter. This is important as it makes carrying the transmitter more
comfortable and allows the transmitter to be held close to the ground ensuring maximum coupling to the
services below.
3.
Switch on the vScan and select 33 kHz line mode.
Stand at least 10m apart holding the equipment as below, i.e. with the transmitter and receiver in line with the
direction of walking.
Adjust the sensitivity of the receiver so that the meter reads approximately 20%.
Walk slowly across the site keeping parallel with each other. As a service is approached the signal level on
the receiver will increase. When the signal is at a maximum, stop the transmitter and place it on the ground.
Then pinpoint the position of the service with the receiver in the usual way. Mark this position and if
necessary plot the route across the site.
Continue the sweep across the site and then, if possible, repeat the process at 90 degrees to the sweep
already done.
4.7.2
“Swamping” an area with Signal (Broad Induction)
A quick way to check an area for services is to “Swamp” the area with signal. To do this, insert the transmitter
into the Tx foot supplied with the transmitter and place on the ground as shown in the picture.
