At 13 o'clock on January 24, a fire broke out on the basement floor of the shop along Jiale Yuan, Tiangong South Avenue, Yushui District, Xinyu City, Jiangxi Province, the fire has caused 39 people to be killed, 8 people are now in relatively stable condition, and one person was rescued.
The "1.24" fire accident held a press conference on the 25th, and it was found that the cause of the fire was because the basement of the building was being renovated in cold storage, and the fire was caused by the illegal fire construction of the construction personnel.
Many people will be surprised when they hear the word cold storage, how can the environment of cold storage catch fire?
The cause of the fire in the cold storage: the source of the fire
First of all, we must know that the fire source of cold storage fire mainly comes from two aspects: equipment failure and human error.
The main reason for the equipment failure is that the electrical equipment used in the cold storage is not a few, and the lighting, cold storage motor, transmission equipment, etc. are all important components in the cold storage system engineering.
Due to the special low temperature environment of cold storage, condensation and freezing of electrical equipment will occur due to heat conduction caused by temperature difference, resulting in a shortened service life.
The service life of some existing cold storage in the mainland is too long, and the electrical equipment has problems such as aging and rupture of the equipment insulation layer, which will increase the probability of short-circuit failure of the equipment.
Faulty and improper use of these electrical equipment can lead to fires.
Another source of fire is human error, cold storage in the initial construction and testing and later demolition process, will involve hot work, hot work will produce high temperature welding slag, cutting sparks and other open flames, if the construction personnel do not operate in accordance with the provisions of the standard, it is possible to ignite combustibles, cause fire.
In addition, in the daily use of cold storage, if there are employees smoking in the cold storage and discarding cigarette butts at will, it may also cause fires.
combustible
In addition, as the three major elements of combustion: combustibles, combustibles, and ignition sources. In addition to the source of fire, there is also combustibles, because the cold storage is not an absolutely closed environment, oxygen as a combustion, so it is not scarce.
There is one more element left is combustibles, and the combustibles in cold storage are divided into three categories, namely insulation materials, cargo packaging and refrigerants.
The first is the insulation material, at present, the insulation materials widely used in cold storage mainly include polystyrene foam, extruded polystyrene foam and polyurethane foam, which is commonly known as EPS, XPS and PU three materials.
EPS will melt after heating, which will cause local heat accumulation of high-temperature flue gas during the combustion process, and a large area of integral combustion will be formed in a short time, which will produce carbon monoxide and decompose a large amount of soot.
XPS, on the other hand, will be pyrolyzed and deformed when heated, melted and dripped, and accompanied by a small amount of smoke, when the temperature rises sharply, it will be accompanied by bright flames and black smoke.
The worst thermal stability is the PU material, which is easy to cause heat accumulation when exposed to high-temperature heat source radiation, and the combustion speed is extremely rapid when encountering high-temperature open flames, and it will also be accompanied by the production of highly toxic hydrogen cyanide, which will cause breathing difficulties and finally suffocation.
When these three insulation materials come into contact with combustion, the temperature will rise rapidly in a short period of time, and decompose and release smoke and toxic gases that are harmful to the human body.
Outer packaging of goods
In addition to the insulation material, there is also the outer packaging of the goods, most of the outer packaging of the goods stored in the cold storage is corrugated material, that is, we often see cardboard boxes used to hold fruits and the like, this material is extremely easy to ignite, coupled with the low temperature and low humidity environment of the cold storage, once ignited, the fire spreads rapidly in an instant.
The last point is the refrigerant, the current refrigerant in the mainland cold storage is mainly liquid nitrogen, which is the raw material for the production of liquid nitrogen ice cream, which is familiar to us as a summer Internet celebrity snack, and the skin will be frostbitten when it comes into contact.
Once this liquid nitrogen is leaked, it becomes a toxic ammonia vapor that can cause harm to the human body. In addition, ammonia vapor is one of the explosive gases, and when the concentration of air reaches the explosion range value, it will explode once it encounters an ignition source.
Cold storage fire and basement fire are double hazards
It is understood that in recent years, there have been a number of cold storage fires, and each fire has caused large casualties. On March 27 last year, 11 workers died in an abandoned cold storage in Cangzhou City, Hebei Province, when workers ignited polyurethane foam while welding.
In December 2021, a cold storage on the second basement floor of the new Changxing Market in Dalian caught fire, killing not only eight people, but also a firefighter.
In November 2017, a fire broke out in the cold storage on the basement floor of an apartment building in Daxing, Beijing, killing 19 people. There was also a fire in the cold storage in the Xinyu Yushui District of Jiangxi Province, which killed 39 people.
Cold storage because they are built underground, underground fire and high-rise fire are the most dangerous two situations, in the case of a fire in the basement, accompanied by a large smoke, firefighters are difficult to see the road even with an empty call, it is very difficult to escape alone, and in most cases can only wait for rescue.
There are many combustibles in the cold storage, once the fire is ignited, the fire will spread very quickly, and it is easy to cause a three-dimensional fire, and because of the relatively closed space of the cold storage. Once the insulation material smoldered in the insulation interlayer, it is difficult to detect.
Once the smoldering state changes to an open flame combustion state, a large amount of smoke is generated, and the temperature rises extremely quickly.
In the process of combustion, these insulation materials will also release a large amount of toxic gases, causing irreparable damage to the human body, and will also cause vomiting, difficulty breathing, dizziness, weakness of limbs, and even suffocation. And the construction area of the cold storage is generally large, and it is easy to cause collapse in the event of a fire.
The combination of the cold storage fire and the basement fire is undoubtedly worse, making the possibility of escape even lower, and also increasing the difficulty of rescue for rescue workers.