Under what conditions are normally open fire doors usually in the open mode?

Fire doors play a vital role in buildings. They not only prevent fires from starting, but also save people and property from fires when they do occur. Among all the fire doors, the normally open fire doors are a very special door, they are usually in the open mode at ordinary times, and they will only be closed when a fire breaks out. So under what function is the normally open fire door usually in the open mode?
First of all, let us understand the structure and characteristics of normally open fire doors. The biggest difference between normally open fire doors and other fire doors is that they are always open. This means that people can enter or leave the building through this door at any time. In terms of door structure, normally open fire doors are not much different from other doors. They are usually composed of door frames, door leaves, sealing strips, handrails, emergency switches, etc. The difference is that the emergency switches of normally open fire doors are generally connected to fire detection systems such as fire detectors, fire alarms, and fire hydrants. It is in the open mode at ordinary times because they are to meet the daily use needs of the building. For example, in shopping malls, hospitals, schools, office buildings and other places with a large flow of people, if the fire doors are closed, it will be very inconvenient once people need to enter or leave the place; therefore, the opening of normally open fire doors The pattern ensures the smooth circulation of the building and the convenience of daily use. So, how does the normally open fire door play a protective role in the event of a fire? This starts with its material and characteristics. Normally open fire doors are usually made of fireproof materials such as steel, and fireproof filling materials are set on the inside of the door, which can effectively isolate flames and smoke. The door sealing strip can seal the crack between the door and the door frame, thereby preventing the fire smoke from penetrating to the outside, and maintaining the effects of ventilation, fire separation and sound insulation. Fire doors can prevent the spread of fire into a building within a specified period of time. The fire protection time of normally open fire doors is generally 1 hour or 2 hours. This automatic closing and locking feature of normally open fire doors is crucial in the event of a fire.
In general, normally open fire doors can ensure the smooth passage of the building and the convenience of daily use in the usual opening mode. When a fire occurs, the automatic closing and locking features can make the door close immediately and control the fire. spread to ensure the safety of personnel and property.