1. Characteristics of fireproof glass

1.1 fire integrity

Under the standard fire resistance test conditions, when one side of the building partition component is exposed to fire, it can prevent the penetration of flame or the emergence of flame on the back fire surface within a certain period of time. That is, the flame appears on the back fire surface of the test piece and continues to burn for 10s or more. In the test, when flame or gas appears from the holes and other gaps of the test piece, the ignition test of the cotton pad is carried out, and the cotton pad is ignited, indicating that the test piece loses its integrity. If the specimen collapses during the experiment, it indicates that the pendant loses its integrity.

1.2 fire resistance and thermal insulation

Under the standard fire resistance test conditions, when one side of the building partition component is exposed to fire, the temperature of its back fire surface can not exceed the specified value within a certain time. It refers to the temperature rise of a single point at the temperature measuring point on the back fire surface of the test piece of 180 ℃ and the average temperature rise of 140 ℃.

1.3 thermal radiation intensity

Under the standard fire resistance test conditions, the thermal irradiance value at a certain distance and time from the back fire surface of the glass. That is, the critical radiant heat illuminance reaches 0.42w/cm at 3M away from the back fire surface of the test piece? And at a distance equal to 1.2 times its smaller size (length or width) from the back fire surface of the test piece, the critical radiant heat illuminance reaches 3.35 w / cm?. If the radiation intensity falling on the cellulose material exceeds 3.35 w / cm?, These materials burn easily.

2. Types of fireproof glass

2.1 classification by fire resistance

Fireproof glass is a kind of special glass that can maintain its integrity and heat insulation under standard fire resistance test conditions. It can be classified according to different methods.

2.1.1 class A

At the same time, the fireproof glass meeting the requirements of fire resistance integrity and fire resistance and heat insulation. In case of fire, the high heat generated by flame combustion passes through the glass in the form of heat radiation and heat conduction, so that the temperature of the back fire surface of the glass continues to rise. When reaching a certain degree, the heat will cause people or combustibles to be burned or ignited without touching the flame. Thermal insulation composite fireproof glass is designed to protect escape and rescue personnel from thermal radiation and reduce the destructiveness of fire to a small extent. Class a fireproof glass is composite fireproof glass.

This kind of glass has the properties of light transmission, fire prevention (smoke, fire and heat radiation), sound insulation and impact. It is suitable for building decorative steel wood fire doors, windows, upper beams, partition walls, daylighting roofs, smoke retaining vertical walls, perspective floors and other building components that need to be transparent and fire-proof.

2.1.2 type B

Fireproof glass that meets the requirements of fire integrity and thermal radiation intensity at the same time. Class B fireproof glass is composite fireproof glass. This kind of fireproof glass is mostly composite fireproof glass, which has the characteristics of light transmission, fire prevention and smoke separation.

2.1.2 class C

Single piece fireproof glass that only meets the integrity requirements of fire resistance. Class C fireproof glass is divided into borosilicate monolithic fireproof glass, cesium potassium monolithic fireproof glass and high-strength monolithic fireproof glass. Borosilicate monolithic fireproof glass is a kind of original glass produced by float process with high borosilicate and tempered. Its fireproof energy comes from its low coefficient of thermal expansion, which is only 4 × 10-6 ℃ - 1 (20 ~ 300 ℃), 2 ~ 3 times higher than the bottom of ordinary glass (silicate glass). In addition, borosilicate monolithic fireproof glass also has the characteristics of high softening point, high thermal shock and viscosity. Therefore, in case of fire, borosilicate monolithic fireproof glass is not easy to expand and crack. It is a kind of monolithic fireproof glass with high stability, and its fire resistance time limit is up to 3H.

Cesium potassium monolithic fireproof glass is made of ordinary float glass through chemical treatment and physical tempering. Among them, the role of chemical treatment is to conduct ion exchange on the surface of glass, so that the alkali metal ions on the surface of glass are replaced by other alkali metal ions in lava, so as to increase the strength of glass and improve the thermal shock performance. Moreover, the physical toughening treatment is carried out to make it meet the requirements of glass. High strength monolithic fireproof glass is made of fireproof glass through physical tempering treatment (high wind pressure). This kind of glass has the characteristics of light transmission, fire prevention, smoke separation and high strength. It is applicable to fireproof glass partition wall, fireproof window, outdoor curtain wall, etc. without thermal insulation requirements.

The fire resistance rating of the above three types of glass is divided into grade I, grade II, grade III and grade IV, and the corresponding fire resistance time is 90min, 60min, 45min and 30min.

2.2 classification by structural type

According to the structural type, there are mainly four kinds of fire-proof glass: laminated composite fire-proof glass, wired fire-proof glass, hollow fire-proof glass and high-strength monolithic fire-proof glass.

2.2.1 laminated composite fireproof glass

Laminated fireproof glass is a kind of architectural glass. PVB film is used between two layers of float glass. It is glued into a whole under a certain temperature and pressure. It is impacted in time. The broken glass is still connected together to prevent casualties and other accidents. The pouring type fireproof glass also belongs to the laminated fireproof glass. The transparent chemical substance poured and solidified in the middle of the heat insulation type composite fireproof glass absorbs a large amount of heat in the flame and foams and expands. At the same time, it becomes opaque white to prevent the heat generated by combustion from being transmitted from the fire facing surface to the back fire surface. In this process, the glass remains intact as a whole, forming a barrier that can block the diffusion and spread of flame, smoke and high-temperature toxic gas generated by combustion. The heat insulation and heat radiation protection functions of composite fire-proof glass can protect the escape or rescue personnel in the area behind the fire surface of the glass from the invasion of high-temperature heat and the burn of heat radiation in case of fire, and prevent the combustible materials and articles in the area, such as wood products and carpets, from being ignited by high-temperature and heat radiation within a certain period of time.

2.2.2 wired fireproof glass

Wired fireproof glass is a composite glass made by adding metal wire and mesh into the interlayer of organic film or inorganic adhesive between two layers of glass. After adding wire or mesh, it can not only improve the overall impact strength of fireproof glass, but also connect with electric heating and alarm system to play a variety of functions. The defect of the fireproof glass is poor light transmittance.

2.2.3 hollow fireproof glass

The hollow fire-proof glass is sealed, isolated and fixed with a support frame around each adjacent two pieces of glass to form a sealed space. The non sealed space is sealed and filled with an outer sealant, and one or more of them use a single piece of fire-proof glass. The contact surface between the support frame and the glass is bonded with inner sealant; The support frame is of inner space structure, filled with desiccant and rectangular structure. The two right angles of its outer edge are made into a chamfer structure of 45 ° and 2mm. The sealing space can be insulated, insulated and reduce noise. The optimized size and good chamfer structure of the support frame make the outer sealant have good fixing conditions, not easy to be deformed and damaged. The sealing performance and radiation resistance are better than those of conventional glass, which fully ensure that there is no condensation and radiation when used for a long time No trace or deformation of adhesive strip.

2.2.4 single piece fireproof glass

Monolithic fireproof glass is obtained by treating float glass with physical and chemical methods. It can keep 80 min ~ 120 min in 1000 ℃ flame without cracking, so as to prevent the spread of flame and smoke, help find the fire at the first time, and allow people to evacuate the site for a long time and carry out disaster relief work.

In addition to ordinary flat glass, which is obtained after physical and chemical tempering, there is also a kind of special single fireproof glass, which specifically refers to the glass with special composition instead of ordinary flat glass. It mainly includes borosilicate fireproof glass, aluminosilicate fireproof glass, microcrystalline fireproof glass and sodium calcium float glass with softening temperature higher than 800 ℃. Its common main characteristics are: the softening point of glass is high, generally above 800 ℃, the coefficient of thermal expansion is low, and generally will not crack or deform due to high temperature under strong flame. In particular, microcrystalline fireproof glass has not only the above characteristics, but also high mechanical strength, high folding, high pressure, good chemical stability and physical and mechanical properties.

2.3 classification by structure

Fireproof glass can be divided into composite fireproof glass and single fireproof glass according to its structure.

2.3.1 composite fireproof glass

Special glass composed of two or more layers of glass or one layer of glass and organic materials and meeting the requirements of corresponding fire resistance rating. Composite fireproof glass can be divided into composite fireproof glass and pouring fireproof glass according to the manufacturing method.

The composite fireproof glass structure is shown in the figure: it is made by bonding and compounding two or more single-layer flat float glass with intumescent flame retardant cement. Its fire prevention principle: in case of fire, the glass facing the fire will burst quickly after encountering high temperature, and its fireproof rubber interlayer will foam and expand about 10 times successively to form a hard milky white foam fireproof rubber plate to block the flame and isolate high-temperature harmful gases.

The structural diagram of pouring fire-proof glass is shown in Figure 2. Two or more single-layer flat float glass are sealed with frame strips around, and then filled with fire-proof liquid (such as silicone or polysulfide sealant) through the pouring port and cemented and sealed. The fire prevention principle is that in case of high temperature, the transparent gel like fire-proof adhesive layer in the middle of the glass will harden rapidly to form an opaque fire-proof heat insulation board. While preventing the spread of flame, it also prevents the high temperature from transmitting to the back fire surface. It is applicable to fireproof doors and windows, building patio, atrium, shared space and partition wall of fire compartment in computer room.

In actual production, the size and thickness deviation of composite glass must meet the following national standards, as shown in Table 1.

2.3.2 single piece fireproof glass

Monolithic fireproof glass is a special glass composed of single-layer glass and meets the requirements of corresponding weather resistance grade. Single piece fireproof glass can maintain fire resistance integrity and block open fire and toxic and harmful gases on the fire facing surface within a certain time, but it does not have the effect of temperature insulation. Single piece fireproof glass is made by toughening ordinary float glass through physical and chemical treatment process, which has good temperature resistance and thermal cracking. Its disadvantage is that it is easy to burst when encountering water under the condition of high flame temperature. It is applicable to external curtain wall, outdoor window, daylighting roof, smoke retaining vertical wall, fireproof glass frameless door and partition wall without thermal insulation requirements. The deviation standard of dimension and thickness of single fireproof glass is shown in Table 2.

3 conclusion

Since the batch production of single piece fire-proof glass in China, fire-proof glass has been more widely used, but there are several points to pay attention to when using: before selecting fire-proof glass, it is necessary to know the specific fire-fighting requirements of fire-proof components composed of fire-proof glass, whether they are fire-proof, heat insulation or smoke-proof, fire-resistant requirements, etc; Single piece and composite pouring fireproof glass cannot be cut with glass knife like ordinary flat glass, and must be processed to a fixed length, but composite (dry process) fireproof glass can meet the requirements of cutting; When selecting fireproof glass to form fireproof components, in addition to considering the fireproof durability of glass, its supporting structure and elements must also meet the needs of fire resistance. However, generally speaking, fireproof glass has good light transmission performance, fire and heat insulation performance, good durability and light resistance, certain impact strength, stable product performance and wide range of ambient temperature. It can be widely used in fireproof doors, windows and fire compartments, and has high popularization and application value.

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