Sometimes, in the construction and use of pipelines, or during the construction/tear-down of buildings, you may need to detect and remove some unknown ferrous object from inside pipes, behind walls, and under flooring. To safely detect the position of an object, you can use a Mobile Hall Sensor Array. 

The main benefit of this method is that it’s considered a non-destructive evaluation (NDE), which is exactly what it sounds like… non-destructive. You can determine your next move before making any costly demolition choices that could cause damage to your product or equipment, or even cause serious injury to employees.

According to the National Center for Biotechnology Center, this technique is most often used by employees to, “evaluate the quality and condition of steel water pipes and steel cables embedded in walls or floors, as it is able to detect cracks and discontinuities within the material under evaluation.”

What is a Mobile Hall Sensor Array?

The motorized system is made up of a sensor and a signal processing unit. The sensor has two permanent magnets (magnets A and B) housed inside a carbon-steel cylinder and a collection of Hall Effect sensors. Permanent magnet A is magnetized in a downward direction and permanent magnet B is magnetized upward. This produces what is called magnetic flux flow (net number of field lines passing through a surface). Then, the collection of sensors detects the leakage flux that exists due to the existence and shape of the unknown or unwanted ferrous object.

The signal unit processes any data collected as the motorized Mobile Hall Sensor array system moves along a surface. As the ferrous object nears, it disrupts the distribution of flux and a 2-D image is constructed from 1-D processed signals. The shape of the object is then determined using an algorithm developed specifically for the application.

Below, you can see an example of the comparison between the object and the resulting image constructed from the signals and algorithm. The second row in the image is what is being “described” and displayed by the Mobile Hall Sensor array system.

magnets and mobile hall sensor array


Call Apex Magnets

Apex Magnets offers its customers a wide assortment of permanent magnets that you can use to test and build this type of Mobile Hall Sensor array. As a contractor or pipeline manufacturer, this could be one of the best options available to save you time, money, and construction-related headaches. 
If you’d like to have a conversation about what our products can do for your unique situation, contact us at (1-304) 257-1193. At Apex, we want to help