What is a handheld metal detector?
Handheld metal detector is a kind of metal detector, which is named because it is used by hand. It is mainly used for factory anti-theft, place security inspection and examination room anti cheating. Compared with security inspection door, hand-held metal detector is more accurate. Alarm through electromagnetic induction of metal objects. The alarm methods mainly include sound, light, vibration, or through headphones.
Hand held metal detectors are designed to detect metal objects carried by people or objects. It can detect weapons, explosives or small metal objects in people’s parcels, luggage, letters, fabrics, etc. The special appearance of its sensitive surface makes it easy to operate. It is superior to ring sensor hand detection. Ultra high sensitivity, special application. Such as prison, chip factory, archaeological research, hospital, etc.
I believe you are no stranger to security inspection. You need security inspection when taking the subway, train and plane. No matter what kind of transport you take, you always have to pass through a door during security inspection, which is often accompanied by a “beep” prompt sound. After entering, the security personnel will check the passengers. This door is called security door, also known as metal detection door. It is a device specially used to detect whether people carry metal objects. We see such products in airports, stations and other places, and the setting of security doors greatly improves its security. The principle used by the security door to detect metal is magnetic field induction technology. When it works, a stable magnetic field distribution will be formed inside the security door. If a metal material passes through the door, it will destroy the magnetic field of the door itself, which will be sensed by the metal detection door and send out an alarm sound. At the same time, the security gate is divided into different areas. The more common areas are zone 6 and Zone 8, and higher areas such as zone 12 and zone 28. When the human body carries metal through the security gate, the alarm sound in the corresponding area will sound. In this way, the security inspectors can find the metal items carried by the human body more quickly and accurately.
After passing through the security door, the security personnel will scan the passing personnel with a hand-held metal detector. The metal detector adopts a rectangular detection head, and the detection area is 12 cm long. When checking the human body, the inspection work will be completed from top to bottom at one time. The working principle of metal detector is similar to that of security door, which also uses the principle of electromagnetic induction. The detector contains a coil containing alternating current to produce a rapidly changing magnetic field. When a metal object is in this magnetic field, it will induce eddy current and then generate a magnetic field. The magnetic field generated by the metal object will affect the original magnetic field, and the alarm device of the metal detector will start, emit a beep and vibrate continuously to inform that there are metal objects nearby. The security personnel generally use the handheld metal detector with the metal detection door. When the “security door” alarms and finds metal objects, the handheld metal detector can find the exact location of the hidden metal objects.
In densely populated places such as stations and airports, X-ray baggage detectors are also used together with security doors and metal detectors to check passengers’ luggage. It is the existence of these security facilities and security personnel that greatly improves the safety of these places.
The handheld metal detector is used to check the specific position of metal carried by people, and can also be used with the metal detection door. When the “security door” alarms and finds metal objects, the handheld metal detector can find the exact position of metal objects. The metal detector adopts a rectangular detection head, and the detection area is 12 cm long. When checking the human body, the inspection work is completed from top to bottom at one time.
Metal detectors include safety door, portable metal detector, handheld metal detector, desktop metal detector, industrial metal detector and underwater metal detector.
Use of handheld metal detector
Public safety inspection
Such as airport security, prisons, courts, testing institutes, banks, hotels, large conferences, sports competitions, concerts and other public security.
Many factory products contain metal components. In order to prevent the loss of enterprise products, security guards inspect employees at the door of important workshops.
Anti cheating in examination
In recent years, the college entrance examination, graduate examination, civil service examination and other examination rooms prevent candidates from carrying wireless headphones and other cheating tools. Each examination room will be equipped with some handheld detectors. At present, many provincial education systems in China are equipped with such products
Principle of handheld metal detector
When a metal object is in a magnetic field, it can induce eddy currents, which can produce a magnetic field, which in turn affects the original magnetic field and changes. At this time, the alarm device of the metal detector will trigger, beep or vibrate continuously to indicate that there are metal objects nearby so that people can find the metal objects. According to the principle of metal detector, people have developed various metal models, such as gold, copper, silver and so on. Because the magnetic field induction intensity and distance of different metals are different, this tests the manufacturer’s technical ability. In addition, the use of metal detectors is divided into many fields.
Precautions for handheld metal detector
- 1. The type of metal detector and detection technology are the main factors affecting the detection ability. In addition, there will be differences between detectors using the same technology, and their additional functions will also be different. For example, some low-frequency detectors use a higher frequency than others, and the coil size of different detectors will vary. In addition, the sensing technology and amplification technology adopted by different manufacturers and different models of products of the same manufacturer are also different.
- 2. Different metal types of the target have different ability to generate magnetic field, and the metal that can generate strong magnetic field is easier to detect. For example, iron can produce a strong magnetic field and is easy to detect, while aluminum is not easy to detect.
- 3. The size of the target affects the magnetic flux, thus affecting the induction intensity. The larger the target, the greater the induced current intensity, and the easier it is to detect. Target composition some substances belong to natural conductors and may seriously interfere with metal detectors. Sideband effect of target if some types of metal targets hide for a long time, it will actually enhance the conductivity of adjacent substances.
Before using the hand-held metal detector, first check whether the machine is abnormal:
- Method 1: pick up the hand-held metal detector and shake it gently to check whether there is abnormal sound;
- Method 2: open the battery box on the handle of the handheld metal detector, and then install the matching battery. Note: (generally, batteries are provided by the manufacturer and are divided into two types: disposable batteries and rechargeable batteries);
- Method 3: usually, the switch of handheld metal detector will be on the handle, and the switch is usually divided into three positions. Some have only one power on button and one power off button. Check whether the signal light is on and take out the prepared one dollar coin. Never check whether the handheld metal detector works normally and whether the detector is in normal use from one angle and different distances. Now we officially use it.
Operation method of handheld metal detector
- 1. Turn on the power switch and hear the “click” sound, indicating that the power is connected and the green light is on. If the green light is not on, it means that the battery is not installed or the battery is in poor contact. If it keeps sounding or vibrating continuously, it means that the battery can not be reused and should be replaced.
- 2. Selection of sound and vibration transfer switch: press the red button switch, and the alarm mode is vibration. Release the red button switch, and the alarm mode is sound.
- 3. After the power is turned on, high sensitivity detection can be carried out. Hold the handle to sweep the detection surface around the tested object. When there are metal objects, an alarm sound or vibration will be sent out, and the green light will turn into red light; Stop detection and scanning, stop the alarm sound or vibration, and the red light turns green.
- 4. Low sensitivity test: if it is necessary to eliminate small objects in metal objects, press and hold the low sensitivity switch. Scan around the tested object. When there are metal objects, the alarm sound or vibration will be sent out, and the green light will change to red light; Stop scanning, the sound or vibration stops, and the red light turns green. At this time, the sensitivity is reduced by more than 5 times. Therefore, at this time, the measured metals are generally relatively large.
Common skills of handheld metal detector
Handheld metal detector is a kind of precision instrument. Only by understanding some common skills of it can we effectively give play to the performance of the instrument.
- The detector shall be preheated for more than 1 minute. Because after most instruments are powered on, some hardware may not fully reach the operating state, but preheat for 1 minute to make the detection results more accurate.
- When using mobile phones, pagers and other electronic devices, please do not use handheld metal detectors
- When using the detection disk of the detection instrument, keep it parallel to the ground and move slowly.
- When using a wide range detector, you can first find the area of the detection target through a wide range search mode, and then detect the metal through a precise mode.
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