Zones in walkthrough gates & sensitivity are the two major decisive factors in choosing the walkthrough gates for the specific application. The walkthrough gates are available as 6 zones to 33 zones. But the question arises that what is the zone, and how it impacts the cost and applicability.
The walkthrough metal detector utilizes the law described by a Scottish physicist named James Clerk Maxwell. He discovered that magnetism and electricity are related as a rule of thumb. An example of the relationship is a coil of copper wire wrapped around the metal nail. When electric current is applied to the coil, the metal nail becomes magnetized. When an electric pulse is sent through a coil of wire, it creates a magnetic field. When the field hits a metal object, it reflects back and can be detected using another coil of wire. The size and timing of the detected pulses are used to define the size and position of the object.
Each magnetic field is a zone and if working independently can be used as overlapping zones.
Walk through metal detectors typically use pulse induction technology, the first induction system sends powerful short burst pulses of current. Each pulse generates a short magnetic field when a piece of metal passes through a magnetic field, a reflected magnetic field is created. This magnetic field then reacts with the receiver coil, which in turn triggers the alarm & light.
These causes to energise the coil. The subsequent current is called the reflected pulse and lasts in few microseconds. A typical walkthrough metal detector sends about 100 pulse pulses per second. But that number can vary based on the model selected.
Ranging from about 20 pulses per second to over 1000 pulses. The walk through metal detectors creates large magnetic fields that cover all of the space inside the rectangular arc of the metal detector. The latest metal detectors have multiple zones
The multi-zone walk through metal detectors contains multiple coils that create the separate detection zones hence detect multiple objects and display all the areas where they can be found. There are alarm lights on the side of the unit making it audible and visible.
In general, the zones in walkthrough gates range from 6 to 33 but not limited.