What is a normally open fire door
Core Working Principle
A normally open fire door is a special fire door that meets national standard fire resistance ratings. It is kept open under normal circumstances to ensure unobstructed pedestrian access. Upon receiving fire alarm signals, it closes automatically to contain fire and smoke. The complete set consists of the fire door leaf and frame, fire-resistant hardware, electromagnetic release device, door magnetic feedback module and fire door monitoring system, all of which are indispensable. Its core safety design features automatic closing upon power failure. Even in the event of fire service power cut or equipment malfunction, the door can close automatically to avoid failure during a fire.
Its core operating logic is simple and reliable:
1.Normal Condition: Powered continuously by a 24V fire control power supply, the electromagnetic release holds the door open steadily without obstructing pedestrian and vehicle traffic.
2.Fire Condition: When a fire alarm is activated in the corresponding fire compartment (interlocking signal from two independent detectors or one detector plus one manual call point), the device loses power and releases the door. The built-in fire door closer drives the door to close smoothly and automatically.
3.Feedback Status: Once the door is fully closed, the door magnetic module transmits the closed-state signal to the fire control room in real time, enabling the control center to accurately monitor the status of fire separation.
Why do public buildings need "open fire doors"?
Let us first look at conventional normally closed fire doors: they remain tightly closed under normal conditions and block fire and smoke in the event of a fire.
This design works well for stairwells in residential buildings, yet it is impractical for shopping malls, hospitals and underground parking garages.
Such premises see heavy foot traffic with constant movement of shoppers, patients and staff. If every fire door needed to be opened and closed manually, movement would become cumbersome and congestion would easily occur. Over time, people prop doors open with stones, trash bins or wooden wedges for convenience.
What was meant to be a fire door turns into an unobstructed opening. Once a fire breaks out, thick smoke and flames spread rapidly through the doorway to the whole building, rendering fire separation completely ineffective.
To tackle this problem, fire codes have specified normally open fire doors. They facilitate smooth passage on a daily basis and activate automatically during fires, striking an ideal balance between accessibility and safety.
