Utility Locating

HomeServicesUtility Locating

Utility Locating

Introduction to Magnetic and Utility Locating

Theory of Operation: Magnets can be defined as bodies that produce external magnetic fields; these fields are bipolar, that is, they will have a positive pole where the field emanates from the object and a negative pole where the field returns. The shape and size of this external field is directly related to the magnet’s strength.

Magnetic locators work by detecting two types of magnetization that can be produced by underground ferrous (iron or steel containing) objects. The first type is the weak field induced naturally by earth’s magnetic field. The first type is the weak field induced naturally by Earth’s magnetic field. All ferrous objects have this field, and in the
Northern Magnetic Hemisphere this field is always positive. The second type is an artificially induced permanent magnetization. When this type of field is present, it is usually quite strong. The field orientation varies depending on how the object was magnetized.

Magnetic locators have two sensors vertically separated about 8 to 20 inches that give a reading when the two sensors are detecting different magnetic field strengths. So when the lower sensor (typically) is near a ferrous object, it will detect a stronger field than the upper sensor and trigger a response, which is usually an audio signal rising in pitch but can also be a numeric indication or bars on a screen.

lets-locate2Magnetic Locators
Magnetic Locators will ONLY locate metal objects that are made of ferrous material. Basically speaking, if a magnet will stick to it, a Magnetic Locator will detect it. Please understand that how deep in the ground you can detect something depends on its mass. A surveying nail you can find up to about 2, maybe 3 feet. An underground storage tank you can find up to about 15 to 17 feet deep. Magnetic Locators will not detect objects such as electrical power cable made of aluminum or copper, since these materials are not considered ferrous. Items that are found using Magnetic Locators are usually cast iron pipes, property corner markers, steel enclosures or hardware, hazmat drums, manhole covers, marker magnets, septic tanks, unexploded ordnance, valve boxes, weapons, and well casings.

Pipe and Cable Locators
With Pipe/Cable Locators, they do NOT detect metal objects like a magnetic locator does. A Pipe/Cable Locator will ONLY locate objects that have some type of charge or signal placed on them. Many utilities give off or transmit a signal of their own that is sometimes detected by a Pipe/Cable Locator such a 60Hz for live for power lines. But, sometimes the person doing the locating must induce a signal onto the line in order to be able to locate it. Most Pipe/Cable Locators have the ability to induce a signal onto an object (like a waterline) using a Transmitter and the object must be metallic in order to conduct the signal. Pipe/Cable Locators typically come with a receiver and a transmitter but not always. It depends on the model you purchase. Some models come with a portable pocket-sized transmitter with limited features, and some come with standard transmitters that are built into a hard case and offer more features for varied situations. To simply describe how a Pipe/Cable Locator works, the transmitter is just like a radio station that’s putting out a signal, and to pick up the radio station you want to listen to (for example your favorite rock music station) you need a receiver. Just like radio stations, the transmitters transmit signals in certain frequencies. Some Pipe/Cable Locators come from the factory with multiple signals to choose from, and some come from the factory with a single frequency that you decide and select before the purchase. To induce a signal onto a pipe or cable, the Transmitter along with Signal Clamps or Alligator Clips that you place or fasten around on onto pipe, fire hydrants, cables, and other utilities or lines that you’re wanting to locate. When accessibility to the utility’s end-points (above ground) not known, the transmitter can also induce a signal from above, through the ground to reach the utility. This method is trying and difficult and time consuming. This allows the Transmitter to send its signal onto the pipe or cable you need to locate. Some Pipe/Cable Locator models come with the accessories like Signal Clamps and Alligator Clamps or Inductive Antennas, and sometimes you have to purchase the accessories separately. Items that are found using Pipe/Cable Locators are usually cable TV lines, fiber optic lines with a metallic conductor alongside, irrigation lines, plastic pipe or conduit (plastic pipe can be located by inserting a sonde or mini-transmitter and locating the sonde), plastic pipe tracer wire, power lines, street light power, and water lines. Note: Sonde method does not always work.

Now hopefully you have a better understanding of how a Magnetic Locator and Pipe-Cable Locator works in the field by the user.

image
http://wlocco.com/wp-content/themes/vanguard/
http://wlocco.com/
#EDB44D
style1
scroll
Loading posts...
#fff
on
none
loading
#fff
Sort Gallery
http://wlocco.com/wp-content/themes/vanguard
on
yes
yes
off
off
ENTER YOUR EMAIL HERE
on
off