Door interlocking: A core technology for security isolation and process control
The core logic of door interlocking is "only one door is allowed to open at a time." It uses mechanical structures or electronic control systems to achieve interlocking between multiple doors, preventing two or more doors from being open simultaneously, thereby maintaining the isolation, cleanliness, or security of a space.
The workflow can be simplified as follows:
1. The system monitors the open/closed status of each door in real time (using components such as door magnetic sensors and infrared detectors);
2. When one door is opened, the control system immediately sends a locking signal to the other doors, restricting their opening through actuators such as electromagnetic locks and mechanical bolts;
3. Only when the opened door is fully closed and triggers a "door closing confirmation" signal will the locking status of the other doors be released, allowing them to open sequentially;
4. Some high-end systems can integrate an emergency unlocking function. In the event of a fire, power outage, or other emergencies, the interlock can be released via an emergency button or automatic sensor, ensuring unobstructed evacuation routes.
Main Types and Characteristics of Door Interlocks
Based on control methods and application scenarios, door interlocks are mainly divided into the following three categories:
Mechanical Interlocks: Simple structure, relying on mechanical components such as gears, linkages, and pins for linkage, requiring no electric drive;
Advantages: High stability, low failure rate, and low cost, suitable for scenarios without power supply or sensitive to electronic equipment (such as some explosion-proof areas);
Limitations: Poor flexibility, unable to achieve remote control or status feedback, only supports basic interlocking of 2-3 doors.
Electronic Interlocks: Use microcontrollers and PLCs (Programmable Logic Controllers) as the control core, combined with electromagnetic locks, magnetic door switches, touch panels, and other electronic components. Advantages: Supports multiple door interlocks (3 or more), enabling visual status display (e.g., indicator lights showing door open/lock status), remote monitoring, and access control (e.g., card unlocking). Limitations: Relies on power supply, requiring backup power for power outages; suitable for scenarios with high functional expandability requirements (e.g., cleanrooms, laboratories)
Smart Interlocks: Based on Internet of Things (IoT) technology, integrating functions such as facial recognition, card swiping, and remote control via APP; Advantages: Real-time upload of door status data to the management platform, support for historical record queries, abnormal alarms (such as door not fully closed, forced opening), hierarchical access control, and adaptability to intelligent scenarios (such as smart laboratories and high-end factories); Limitations: Higher cost, requires a certain level of network stability, and necessitates professional system maintenance.
Core Technological Advantages of Door Interlocks
Forced Isolation, Eliminating Security Vulnerabilities: Through physical or electronic locking mechanisms, the risks caused by "multiple doors opening simultaneously" are fundamentally avoided. This is more reliable than manual management and reduces security risks caused by human error.
Standardized Processes, Improved Management Efficiency: Guides personnel to enter and exit according to the standardized "close before open" procedure, eliminating the need for dedicated personnel for supervision, reducing management costs, and creating traceable operation records (electronic/intelligent type).
Strong Environmental Adaptability: Mechanical, electronic, and intelligent types can be selected according to different scenario needs. Customization is supported for special environments such as normal temperature, high temperature, low temperature, explosion-proof, and moisture-proof, meeting diverse usage requirements.
Emergency Support, Balancing Safety and Escape: High-end systems are equipped with emergency unlocking functions, allowing for rapid disengagement of the interlock in emergencies without affecting personnel evacuation, balancing safety control and emergency rescue needs.
Door Interlock Selection and Installation Considerations
Clarify Usage Scenarios:
Based on the space's purpose (e.g., laboratory, cleanroom), isolation requirements (e.g., leak prevention, contamination prevention), and the number of doors (2 doors / multiple doors), select the appropriate interlock type to avoid functional redundancy or inadequacy.
Focus on Core Performance Parameters:
Locking Method: Electromagnetic lock (fast response), mechanical bolt (strong tamper resistance);
Response Time: Electronic/intelligent types must ensure unlocking/locking response ≤ 1 second to avoid jamming;
Protection Level: For outdoor or humid environments, select components with an IP54 or higher protection rating;
Emergency Function: Prioritize products equipped with backup power and emergency buttons.
Compatibility and Expandability: If integration with existing access control systems and monitoring platforms is required, select products that support standardized interfaces (e.g., RS485, TCP/IP) to allow for future functional upgrades.
Compatibility and Expandability: Professional installation and debugging: The installation accuracy of the door, the sensitivity of the sensors, and the programming and debugging of the control system directly affect the interlocking effect. Installation must be performed by professional technicians to ensure that one door is fully closed before unlocking another, preventing accidental triggering.