In fact, Whether it is commercial fire doors or residential fire doors, fire doors are generally divided into normally closed and normally open fire doors:
1. Normally closed fire door: It is usually closed and needs to be pushed open when people move around. Disadvantages of normally-closed fire doors: they open and close frequently when there is a large flow of people in large buildings and shopping malls. The fire doors will be damaged very quickly, and of course they will not play a role in fire protection.
2. Normally open fire door: it is always open and will automatically close in case of fire. Because it is kept open at ordinary times, it is convenient for personnel to pass through, and it is convenient for ventilation and lighting. When a fire occurs, it can be closed by itself to prevent smoke and fire. At the same time, fire safety is guaranteed. Therefore, in the evacuation stairwells of some large shopping malls and shopping malls, always open fire doors are installed.