Manual

Locating Valve Boxes
Both the valve and its casing, when iron, provide strong magnetic fields that
make them easy to locate. Plastic enclosures containing magnets are easily located
at depths of 10 feet or more.
Figure 15. Locating Valve
Boxes and Casings
Locating Cast-Iron Pipes
As illustrated in Figure 16, cast-iron pipes produce the strongest magnetic signals at their joints.
Figure 16. Signal Patterns Provided by Cast-Iron Pipes
The initial search should be performed as follows:
1. Adjust the sensitivity level for maximum.
2. Hold the locator vertically approximately 1 to 1-1/2 feet above the surface.
3. Walk along without turning or tilting the locator.
4. Mark the locations where the maximum signal levels occur.
5. Return to an area of maximum signal strength and hold the locator several inches above the surface.
The sensitivity will probably have to be reduced during this second pass. Four-inch pipes can be located
at depths of up to 10 feet.
Schonstedt Instrument Company 8