RIDGID NaviTrack II - Manual (Page 23)

NaviTrack® II
22
Getting The Most Out
Of The NaviTrack® II
The basic features of the NaviTrack® II make it quick to learn.
But the instrument also has advanced features that will make
locating in tricky conditions much easier if the operator
understands what they are showing him.
More on Informational Locating
The normal shape of a field around a long conductor such as a
pipe or cable is circular. When over the center of a circular field,
expect the following indicators:
• Maximum signal strength
• Maximum Proximity Signal (Line Trace Mode)
• Centered trace lines
• Reasonable and consistent depth reading
• Sound pitch and volume will increase until they
maximize over the line.
The experienced operator learns to “see” the ground situation
by knowing how the different pieces of information provided
by the NaviTrack® II relate to each other. While a simple
straightforward locate of a circular field is fast and easy, tracing
a line which is near other large conductors such as power lines,
phone lines, gas mains or even buried scrap metal can lead to
questions which can only be correctly answered by taking all
the available information into account.
By comparing signal strength, angle, proximity signal, the
Signal trace lines, and depth an operator can see which way the
field is being distorted. Comparing the field information with
an educated view of the ground, noticing where transformers,
meters, junction boxes, manholes and other indicators are
located can help in understanding what is causing field
distortion. It is important to remember, especially in complex
situations, that the only guarantee of the location of a particular
line or pipe is actual inspection, such as by potholing.
Compound or complex fields will produce different indications
on the NaviTrack® II which will show what is happening.
•
Disagreement between trace lines
• Inconsistent or unrealistic depth signal
• Fluctuating random indications (also caused by very
weak signal)
• Inconsistent proximity signal (line trace mode)
• Signal strength maximizing off to one side of the
conductor
Notes on Accuracy
Depth, Proximity and Signal Strength measurements rely
on a strong signal being received by the NaviTrack® II.
Remember that the NaviTrack® II is used above ground to
sense electromagnetic fields emitted from underground lines
(electrical conductors like metal wires and pipes) or sondes
(actively transmitting beacons). When the fields are simple
and undistorted, then the information from sensed fields is
representative of the buried object.
If those fields are distorted and there are multiple interacting
fields, it will cause the NaviTrack® II to locate inaccurately.
Locating is not an exact science. It does require the operator to
use judgment and look for all the information available beyond
what the instrument readings may be. The NaviTrack® II will
give the user more information but it is up to the operator to
interpret that information correctly. No locator manufacturer
will claim that an operator should follow the information
from their instrument exclusively. A wise operator treats the
information he gets as a partial solution to the problem of
locating and combines it with a knowledge of the environment,
utilities practices, visual observation and familiarity with the
instrument to arrive at an informed conclusion.
Locating accuracy should not be assumed under certain
conditions:
• When other lines or utilities are present. “Bleed over”
causes distorted fields and will illuminate lines other than
the target line. Use lower frequencies when possible and
eliminate all connections between the two lines.
Figure 37: Bleed-over
•
When T’s, turns or splits are present in the line. When
following a clear signal that suddenly becomes ambiguous,
try seeking in a circle of about 5-6 m around the last known
point to see whether the signal picks up again. This may
reveal a branch, joint or some other change in the line. Be
alert to “split opportunities” or sudden changes of direction
in the utility being traced.