The products exposed on 315 are really deadly if they are fake! Don’t take it lightly!

A type of glass called fireproof glass was exposed at the 315 Gala.

Unscrupulous businesses deliberately use real fireproof glass to deceive the competent authorities for acceptance, and then use counterfeit and shoddy products to defraud consumers of their money. They deceive their superiors and subordinates, produce and sell counterfeit products, and lay hidden dangers to the safe operation of society.

Fake fireproof glass poses a safety hazard (Source: Screenshot of the 315 Gala)

What is fire-resistant glass?

Fireproof glass is a fireproof material used to control the spread of fire and block smoke and poison. After special processing, fireproof glass can maintain its integrity and heat insulation in the fire, further ensuring the safety of life and property. It is widely used in commercial buildings, schools, hospitals, industrial facilities and other places, especially in key areas such as fireproof partitions, emergency exits, and emergency passages.

Fireproof glass can be divided into 5 grades according to its fire resistance performance, that is, the fire resistance time is 0.5 hours, 1 hour, 1.5 hours, 2 hours, and 3 hours respectively. The fire resistance performance of fireproof glass is closely related to the fire resistance grade. The higher the fire resistance grade (fire resistance time), the better the fire resistance performance of the fireproof glass . The corresponding fire insulation type and integrity are better.

Why does glass shatter when exposed to high temperatures?

Before understanding why fireproof glass is fireproof, let's first talk about why glass shatters at high temperatures. The reason why glass shatters at high temperatures is mainly related to its thermal expansion characteristics and physical structure .

Substandard fireproof glass shatters quickly when exposed to high temperatures (Source: Screenshot of the 315 Gala)

When glass is heated unevenly, it also expands unevenly. One part of the glass may expand more than the other, causing stresses inside. If these stresses exceed the tensile strength of the glass, the glass will break.

Glass is poorly adapted to temperature changes, and rapid temperature changes (such as thermal shock) can cause a temperature gradient between the surface and the interior of the glass, which can generate stress sufficient to cause the glass to break .

315 Anti-counterfeiting of cesium potassium fireproof glass

How does it work?

The 315 Party exposed a kind of fireproof glass - cesium potassium fireproof glass . Cesium potassium fireproof glass is a kind of single-piece fireproof glass, which is a fireproof glass obtained by the old-fashioned spraying method.

The spraying process is to spray transparent fire retardant liquid on the surface of single-layer or multi-layer flat glass substrate. The main components of the fire retardant liquid usually include cesium (Cs) and potassium (K) salts. Under high temperature conditions, through ion exchange, the larger cesium ions and potassium ions in the fire retardant liquid replace the sodium ions on the surface of the glass, and then through physical tempering, a certain surface compressive stress is formed on the surface of the glass, which can resist the thermal stress generated when the glass is heated, thereby making the glass have fire retardant function.

Spraying fire retardant liquid on glass (Source: Screenshot of 315 Gala)

In fact, during the production process of cesium potassium fireproof glass, only one side of the glass is sprayed. The process is relatively backward, and there will be cesium potassium chemical residues on the sprayed surface, which may cause harm to the human body and the environment. In addition, the light transmittance of the finished glass is not high, and the fireproof effect will be weakened if it is exposed to the sun and rain for a long time.

In addition to cesium potassium fire-resistant glass, other monolithic fire-resistant glass was also mentioned in the evening party - high stress fire-resistant glass and high borosilicate fire-resistant glass .

High stress fireproof glass is made by heating the original glass to the softening point, and then rapidly cooling the glass surface to form a high surface stress on the glass surface, so that the glass has sufficient ability to offset the impact of thermal stress caused by temperature difference during fire. The internal fire time is about 1 hour, thus ensuring the integrity of the glass under high temperature conditions of fire.

High borosilicate fireproof glass contains B2O3, Al2O3 and other raw materials, which increase the softening point of glass and reduce the thermal expansion coefficient. It can withstand extremely high temperature changes without breaking, and the fire resistance time can reach 3 hours.

The above three types of single-piece fireproof glass have good fireproof effects. High borosilicate fireproof glass has higher stability , high stress fireproof glass is greatly affected by ambient temperature, and the current market share of cesium potassium fireproof glass is decreasing.

Composite fireproof glass

In addition to single-layer fireproof glass, there is also a type of composite fireproof glass, which is a special glass composed of two or more layers of glass or a layer of glass and organic materials, and meets the corresponding fire resistance requirements. Composite fireproof glass can be divided into laminated composite fireproof glass and perfusion fireproof glass.

Schematic diagram of fire-resistant glass (Source: generated by the author using AI)

Laminated composite fireproof glass is made by bonding two or more layers of single-layer flat glass together with an intumescent flame-retardant adhesive, or by pressing a piece of glass with an organic material into a composite. When a fire occurs, as the temperature rises, the gel decomposes and expands rapidly to form an insulating layer that blocks the spread of flames and heat radiation and acts as a heat insulator.

Infusion fireproof glass is a sealed frame consisting of two or more layers of single-layer glass, which is poured with fire-resistant liquid from the pouring port and cast by gluing and sealing. When exposed to high temperature, the transparent jelly-like fireproof adhesive layer in the middle of the glass will quickly harden to form an opaque fireproof insulation board. While preventing the spread of flames, it also prevents the high temperature from being transmitted to the back of the fire.

summary

As the urban population increases, the building density in the city increases, and the use of glass curtain walls in the exterior wall design of high-rise buildings becomes more and more common. Once a fire occurs, counterfeit and inferior fireproof glass will make it difficult to put out the fire, and the continuous spread of the fire will bring huge economic losses to people. Therefore, in the design and construction of high-rise buildings, it is very important to select and use qualified fireproof glass. At the same time, there should also be strict standards and supervision systems to ensure that all fireproof glass products used are certified and meet national and international fire safety standards.

References

[1] Liu Zhixiang, Deng Pengfei, Pan Shihao, et al. Classification and research status of fire-resistant glass[J]. Guangzhou Chemical Industry, 2021, 49(15):16-18.

[2] Xu Wenfei, Wang Yijie, Liang Runjie. Research on rapid detection technology of single-piece fireproof glass[J]. Fire Science and Technology, 2022, 41(05): 627-629+670.

[3] Feng Yunxi, Cao Yanping. Innovative performance and market application of high borosilicate 4.0 fireproof glass[J]. Building Materials World, 2020, 41(05):51-54.

[4] Cheng Yousui. Analysis on the application of fire-resistant glass in curtain walls of high-rise buildings[J]. Guangdong Building Materials, 2015, 31(12): 21-23.

Planning and production

Author: Denovo team science team

Review丨Teacher Cao Wangbei Materials Engineer

Planning丨Ding Zong

Editor: Ding Zong

Proofread by Xu Lailinlin