A staple in the surveyor’s toolbox, this instrument can pay big dividends if you learn the fine points of using it.
The capabilities of a Magnetic Locator are virtually limitless, and an experienced operator will find many uses for this instrument. Utility companies and other services use them to locate water valves, water meters, gas and water pipes, manhole covers, and even septic tanks.
When used properly, a magnetic locator will greatly simplify the task of pinpointing survey markers. Just turn on the power and adjust the volume control to a comfortable level. Most survey pins can be located quickly and easily with the sensitivity control set on the number 3 setting. Just wave the locator back and forth as you walk along, and you will have no difficulty locating your pin. The locator’s audio output idles when there are no ferrous targets nearby. However, it will gradually increase in frequency as you approach your target, and finally peak directly over your survey pin.
But how does this seemingly magic instrument do this? The primary sensing elements are Fluxgate Magnetometers; they measure the average magnetic field component along the instruments sensitive axis, i.e. along the vertical axis of the sensor tube.
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