In airports, train stations, venues, factories, and other locations, walk-through metal detectors and hand-held metal detectors serve as the first line of defense in daily security. With prolonged high-load operation, issues such as decreased sensitivity and increased false alarms are inevitable. Proper maintenance not only ensures detection rates but also extends equipment lifespan.
1. Sensitivity Calibration: Not Higher Is Better
Sensitivity determines the smallest metal object the equipment can detect. However, higher sensitivity is not always better—too high leads to frequent false alarms, while too low may cause missed detections.
The core of calibration is "matching the scenario." For example, in electronics factories to prevent metal carry-in, extremely small screws need to be detected; while for large event security, the focus is on larger metals like knives and clubs. It is recommended to use standard test pieces (such as iron or copper sheets of specific sizes) for regular verification.
During operation, first confirm the equipment is in normal self-test status, then enter calibration mode according to the manual. Typically, test pieces need to pass through different areas of the walk-through detector (left, center, right, top, bottom) to observe if alarms are consistent. For hand-held detectors, test responses to different metals at standard distances (e.g., 5-10 cm).
It is recommended to perform a complete calibration quarterly, and for high-traffic locations, monthly. Calibration records should be archived to track changes in equipment status.
2. False Alarm Troubleshooting: Approach from Both Environment and Equipment
False alarms are the most troublesome issue for security personnel. Common causes fall into three categories: environmental interference, equipment failure, and improper operation.
Environmental interference is the most common. Large metal structures, moving elevators, walkie-talkies, or even cell phone base stations near the walk-through detector can trigger false alarms. During troubleshooting, temporarily turn off nearby suspicious electrical appliances and observe if false alarms disappear. If false alarms occur at fixed positions, check for rebar or metal floor tiles.
For equipment failure, focus on checking if coil connectors are loose, power supply is stable, and sensors are dusty. False alarms in hand-held detectors are often due to low battery or iron filings adhering to the probe surface.
Improper operation also requires attention. For example, metal chairs or debris should not be placed in the walk-through detector passage; hand-held detectors should not be swept close to the ground or walls.
It is recommended to establish a "false alarm log" recording time, location, and symptoms. Continuous statistics for a week often reveal patterns. If the false alarm rate exceeds 5%, the equipment should be shut down for repair.
3. Daily Maintenance and Lifespan Management
With proper maintenance, walk-through detectors can last 8-10 years, and hand-held detectors 3-5 years. The key is dust prevention, moisture protection, and impact resistance.
During daily shift changes, wipe the equipment surface with a dry soft cloth and check power cords and connectors. For hand-held detectors, inspect the probe for cracks and the battery compartment for leaks.
Weekly, clean the transmitting and receiving windows on both sides of the walk-through detector to prevent dust from blocking infrared or electromagnetic sensors. In humid environments, place desiccants inside the equipment and replace them regularly.
Monthly, check fixed screws and brackets to prevent loosening due to vibration. For equipment not in use for long periods, power it on monthly to prevent capacitor aging.
For lifespan management, it is recommended to establish equipment files recording activation date, repair history, and calibration data. When the equipment frequently fails to calibrate, has persistently high false alarm rates, or shows obvious casing deformation, replacement should be considered.
Finally, a reminder: any maintenance operation should be performed with power off or in safe mode, and follow the manufacturer's manual. If the equipment is still under warranty, prioritize contacting the original manufacturer's after-sales service to avoid voiding the warranty by disassembling it yourself.
Proper maintenance is not an extra burden, but a necessary investment to ensure security quality and reduce long-term costs.