Due to a lot of violence worldwide, security measures on many public places have become much better and more serious. It is very common that in extremely crowded places such as airports, cinemas and malls we will see walk through metal detectors. These devices are able to maintain the security in a much better level as they are proven to be very useful in detecting dangerous objects such as guns, knives, etc. Next to walk through metal detectors, a lot of security personnel are also using hand held metal detectors.
Metal detectors are very compact machines and are based on a PI (Pulse Induction) system. What does this mean? The PI system indicates a coil of wire that is considered as the transmitter, which is placed on the top of the detector and acts as a receiver of magnetic fields. With the help of that wire, pulses of electricity are being created while at the same time reversing the polarity of the magnetic fields. Each second, hundreds of pulses of electricity are sent, however this depends on the model of the metal detector you are using, as some of them are able to create around 25 per second, and some more than a 1000 per second.
When a metal object passes though the electromagnetic field, this will cause a reflected pulse which will last around for a couple of seconds. So, when the presence of a metal object is detected, the sampling circuit will send signal which will beep. This is the classic beep sound that you commonly hear on airports or malls, when someone with a metal object passes through a detector. In many situations this beep will occur when you have keys in your pocket, some loose change, cell phone or similar, and for this reason you are usually being asked to remove these items from your pockets before going under a walk through metal detector. If even after this the machine continues to beep, you will be checked with a hand held metal detector to detect the cause of the alarm.
There are different types of metal detectors, and to some the sensitivity of metal detection can vary a lot. For example, if the sensitivity is too high, the beep sound will happen even if you have loose change in your pocket or even piercings or earrings. In high security areas this is essential though. From the other side, having a high sensitive metal detector in malls and shopping centers doesn’t make much sense as it will make too much noise too often, and therefore the detection of more dangerous objects such as knives or guns can become more challenging.
There are also portable walk through metal detectors. These are used for temporary events such as exhibitions for example. Portable detectors can be used in shops, hotels, malls, and can be easily purchased online. Some events will really require safety measures, so if you are planning to throw an enjoyable and safe event, you should definitely opt for portable systems for the security of your premises.
The first archway detector was built somewhere in the 60´s and at that time it has a purely industrial use. During the years, the use of such devices evolved and today they are used for security reasons in most cases. In the early 70´s, the first walk though metal detector was implemented in the US airports. However, there are a lot of other places where the use of such metal detectors is simply a must – schools, malls, shopping centers, concerts and similar public events, government buildings, prisons, etc.