Normally closed type fire door do you understand the important role in fire? In the event of a fire, if the normally closed type fire door is closed, the critical moment can be saved! However, if the normally closed type fire door is opened for convenience on weekdays, it will not be too late to close it in case of fire.
In our daily life, there is a door that should be kept closed. Do you know what it is?
Yes, that's normally closed type fire door. However, many people often open it for convenience. Once a fire occurs, it may cause greater casualties.
Normally closed type fire door is a kind of fire door, which can meet the requirements of Fire Resistance Stability, integrity and heat insulation within a certain period of time. It is located in fire prevention interval, evacuation staircase, vertical shaft and other fireproof partitions with certain fire resistance.
Fire doors not only have the function of ordinary doors, but also prevent the spread of fire and smoke, which can prevent the spread of fire within a certain period of time and ensure the evacuation of personnel.
Normally closed chimney-proof effect hazard
In the data released by the Ministry of Public Security, it can be found that about 60% of the victims of smoke poisoning died in evacuation passages or corridors or even homes far from the ignition point. This is because the flow direction of flue gas is the way of fire spreading, and the spread speed of flue gas is very fast.
Fire experts pointed out that the flow speed of flue gas in the vertical direction is 3~5 metre per second, which is 8~10 times of the flow speed in the horizontal direction and 5 times of the fire spreading speed.
Take a 33-storey building as an example. Under the condition of no barrier, the smoke can spread from the ground floor to the top floor in about 30 seconds through the evacuation stairs.
Experiment
In order to verify the role of the normally closed type fire door in the fire, someone once specially conducted an escape passage smoke experiment in an abandoned four-storey family hotel.
The experiment simulated that the an electric radiator of the living room of the suite on the second floor was close to combustibles to cause fire. The experimenters set three fire doors between the two bedrooms and the living room on the second floor and the living room and the evacuation passage. Suppose someone was trapped in one of the bedrooms when the fire broke out.
Scenario 1
Normally closed type the fire door is closed. After 4 minutes of fire, the fire is getting bigger and bigger. At this time, the people trapped in the bedroom found the fire and prepared to escape and evacuate.
Because the normally closed type fire door is closed, the smoke and flame have not spread to the escape channel. The fire door has played a good role in fire prevention and smoke isolation, and the trapped personnel have been successfully evacuated.
Scenario 2
Normally closed type the fire door is in the open state. In less than 10 seconds after the fire door is opened, the whole corridor on the second floor is filled with toxic smoke and spreads upward quickly. 20 seconds later, the smoke filled the evacuation passage of the whole building. If the trapped people choose to escape at this time, they cannot escape safely at all.
The following is a video to help you better understand the importance of normally closed type fire doors:
The laboratory personnel detected the toxic gas content in the on-site flue gas through instruments and found that when the height is about 1.5 meters, the carbon monoxide value is 200ppm and the sulfur dioxide value is 0.8ppm; when the height is about 0.5 meters, the carbon monoxide value is 42ppm and the sulfur dioxide value is 0.4ppm.
Firefighters pointed out that if they escape at this time, they should cover their nose and mouth with wet towel and bend down to evacuate.
According to the requirements of National Fire Protection code for building design, normally closed type fire doors should be kept closed at ordinary times. When people open and pass, the door closer on the door will automatically close the fire door. This kind of fire door can effectively block the invasion of smoke and fire after a fire. The normally closed type fire door will be open. Once a fire occurs, the fire door will not play its due role in preventing the spread of fire and smoke.
If it is open for a long time, normally closed type the fire door is light, it cannot return to position normally. If it is heavy, it may damage the door frame and door panel, making it lose the role of smoke and fire prevention. If the fire door loses its function, once a fire occurs, it is easy for "small fire" to cause "major disaster".
What kind of fire door is qualified
900 ℃ flame class a fire door can resist for one and a half hours:
According to relevant sources, the fire resistance of fire doors can be divided into three levels: A, B and C. Class A fire doors can resist the flame burning of 900℃ for 1.5 hours, and type-B fire door can resist the flame burning of 900℃ for 1 hour, class C fire door can resist the flame burning at 900℃ for half an hour. If it is less than half an hour, the fire door is an unqualified fire product.
Fire tips:
Normally closed type fire door is a fire separator with low cost and convenient installation, which is mostly used for the entrance and exit of staircase and the opening of pipeline shaft. The door closer fire doors installed with automatic normally closed type are widely used. Under the condition of excellent quality and normal closing, it can effectively prevent the spread of fire and smoke and make room for people to escape through stairs. The fire department will carry out fire fighting supervision and inspection by going deep into multi-storey buildings and high-rise buildings from time to time, and will try its best to eliminate potential fire safety hazards. Once it finds that the fire doors of the plus-sized are opened or damaged without authorization, it requires relevant personnel to immediately rectify them, and carry out administrative punishment according to the provisions of relevant laws and regulations such as the fire prevention law.
Finally, I would like to remind you that if you see the normally closed type fire door open or locked, it will not work. Once you find the cause of death open or locked, you will be notified to the relevant departments in a timely manner. Besides fire and smoke prevention, the fire door is also a door to escape. If you turn a blind eye, when a fire occurs...
