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The two weaker indications occur because the locator is extremely sensitive to the magnetic field
components parallel to its long axis. At point
B
and
C
the field is perpendicular to the locator so no peak
audio or bar graph (XTd model only) indications are produced at these points.
Correct Stake Orientation
When Placing Stakes, Correct orientation is Important
For checking purposes, the orientation of the pin relative to the locator is shown in
Figure 11. Check the pin with one orientation. Then rotate the pin 180°. The
orientation which gives the largest reading is the one that should be used. This
reading should be positive in the Northern Hemisphere, and negative in the
Southern Hemisphere.
An iron pin has two types of magnetization. One is the magnetization induced by
the Earth's magnetic field. The induced magnetization is always downward in the
Northern Magnetic Hemisphere and produces a positive output no matter which end
of the stake is driven into the ground. The other type of field is the permanent
magnetization which is fixed to the pin. For maximum detection, the stake should
be driven into the ground such that the permanent magnetization is in the same
direction as the induced magnetization.
Figure 11. Checking a Stake’s Orientation
Locating Manholes, Septic Tanks and Well Casings
The magnetic field is strongest at the edge of a shallow manhole cover. You can easily trace the edges of
covers near the surface. Locating depth ranges up to 8 feet. The great length of a well casing provides a
strong field at the surface that makes it easy to locate casings buried up to 15 feet deep.
Figure 12. Locating Manhole Covers
Figure 13. Locating Water Well Casings
Summary of Contents for GA-92 XT
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