Discussion on the Characteristics and Classification of Fire-proof Glass
1. Fireproof glass properties
1.1 Fire Resistance Integrity
Under standard refractory test conditions, the ability of building partition members to prevent flame penetration or flame appearing on the back of fire for a certain period of time when one side of the partition is under fire. That is to say, the flame appears on the back of the specimen and burns continuously for 10 seconds or more. In the test, when the flame or gas appears from the hole and other cracks, the cotton pad ignition test is carried out and the cotton pad is ignited, indicating that the test piece is incomplete. If the specimen collapses during the experiment, it indicates that the pendant is incomplete.
1.2 Refractory and Heat Insulation
Under the standard fire-resistant test conditions, when a certain side of the building partition member is under fire, the temperature of its back fire surface can not exceed the specified value in a certain period of time. That is to say, the single point temperature rise of the back fire surface of the specimen is 180 C, and the average temperature rise is 140 C.
1.3 Thermal Radiation Intensity
Under the standard refractory test conditions, the thermal radiation illumination value at a certain distance and a certain time on the glass back fire surface. That is to say, the critical radiant heat illumination reaches 0.42W/cm at the distance of 3 m from the back fire surface of the specimen and 3.35 W/cm at the distance of 1.2 times the smaller size (length or width) from the back fire surface of the specimen. If the radiation intensity falls on cellulosic materials exceeds 3.35 W/cm?, these materials will burn easily.
2. Types of Fireproof Glass
2.1 According to fire resistance
Fire-proof glass is a kind of special glass which can keep its integrity and heat insulation under standard fire-proof experimental conditions. It can be classified in different ways.
2.1.1 class A
At the same time, fire-proof glass which meets the requirements of fire-proof integrity and heat insulation, when confronted with fire, the high heat generated by flame combustion passes through the glass in the form of heat radiation and heat conduction, which makes the temperature of glass back fire surface rise continuously. To a certain extent, heat can cause people or combustibles to burn or ignite without touching the flame. Insulating composite fire-proof glass is designed to protect escaping and rescue workers from thermal radiation damage and minimize fire damage. Class A fireproof glass is composite fireproof glass.
This kind of glass has the properties of light transmission, fire protection (smoke insulation, fire insulation, thermal radiation shielding), sound insulation, impact resistance and so on. It is suitable for steel and wood fire doors, windows, upper beams, partition walls, lighting roofs, smoke-proof vertical walls, perspective floors and other transparent and fire-proof building components.
2.1.2 B class
At the same time, it meets the requirements of fire-resistant integrity and thermal radiation intensity. 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, fireproof and smoke isolation.
2.1.2 C class
Monolithic fireproof glass that only meets the requirements of fireproof integrity. 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 content, which is tempered and processed. Its fireproofing performance comes from its very low thermal expansion coefficient, which is only 4 x 10-6 C-1 (20-300 C), 2-3 times higher than that of ordinary glass (silicate glass). In addition, borosilicate monolithic fireproof glass also has high softening point, excellent thermal shock resistance and viscous properties. Therefore, when a fire occurs, the borosilicate monolithic fireproof glass is not easy to expand and crack. It is a kind of high stability monolithic fireproof glass, and its fireproof time limit is as high as 3h.
Cesium potassium monolithic fireproof glass is made of ordinary float glass after special chemical treatment and physical toughening. Among them, the effect of chemical treatment is 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 the lava, thus increasing the strength of glass and improving the thermal shock resistance. And special physical toughening treatment makes it meet the requirements of safety glass. High strength monolithic fireproof glass is a kind of fireproof glass made by special physical toughening treatment (high wind pressure). This kind of glass has the characteristics of light transmission, fire protection, smoke isolation and high strength. It is suitable for fireproof glass partition wall, fireproof window and outdoor curtain wall without heat insulation requirement.
The refractory grades of these three kinds of glasses are classified into grade I, II, III and IV, and the corresponding refractory time is 90 minutes, 60 minutes, 45 minutes and 30 minutes.
2.2 By structural type
Fire-proof glass can be divided into four types according to its structure: sandwich composite fire-proof glass, sandwich fire-proof glass, hollow fire-proof glass and high-strength monolithic fire-proof glass.
2.2.1 Sandwich Composite Fire-proof Glass
Sandwich fireproof glass is a kind of building safety glass. It is made of PVB film between two layers of float glass. Under certain temperature and pressure, the laminated fireproof glass is glued to form a whole, which is impacted in time. The broken glass is still connected to prevent casualties and other accidents. Perfusion-type fire-proof glass is also sandwich fire-proof glass. The special transparent chemical solidified in the insulating composite fire-proof glass absorbs heat in the flame and foams and expands. At the same time, it becomes opaque white, which effectively prevents the heat transfer from the front to the back of the fire. In this process, the whole glass remains intact, forming an effective barrier to prevent the diffusion and spread of high temperature toxic gases produced by flame, smoke and combustion. The heat insulation and radiation protection function of the composite fire-proof glass can prevent the escape or rescue personnel from high temperature heat in the area of the back fire surface of the glass in case of fire.
2.2.2 Sandwich Fireproof Glass
Sandwich fireproof glass is a composite glass made by adding wire and mesh into the interlayer of organic film or inorganic adhesive between two layers of glass. After adding wire or mesh, not only the overall impact strength of fireproof glass can be improved, but also it can be connected with electric heating and safety alarm system to play a variety of functions. The only defect of the fireproof glass is its poor transmittance.
2.2.3 Hollow Fireproof Glass
The hollow fire-proof glass is between two adjacent pieces of glass. It is sealed and fixed with a supporting frame around it to form a sealed space. The non-sealed space is filled with an outer sealant seal. One or more pieces of it are made of a single piece of fire-proof glass. The contact surface between the supporting frame and glass is bonded with inner sealant; the supporting frame is hollow structure, filled with desiccant and rectangular structure. The two right angles of the outer edge of the supporting frame are made into 45 degree and 2 mm chamfer structure. The sealing space can insulate heat, insulate temperature and reduce noise. The optimum size of the supporting frame and good chamfer structure make the supporting frame insulate, insulate and reduce noise. The outer sealant has good fixing conditions, is not easy to be deformed and damaged, and has better sealing and irradiation resistance than conventional glass. It fully ensures that no condensation, no trace and no strip deformation occurs during long-term use.
2.2.4 Monolithic Fireproof Glass
Monolithic fireproof glass is obtained by physical and chemical treatment of float glass. It can keep 80 minutes to 120 minutes in 1000 C flame without bursting, which effectively prevents the spread of flame and smoke, is conducive to the first time to find the fire, so that people can evacuate the scene for a long enough time and carry out disaster relief work.
In addition to the physical and chemical toughening of ordinary flat glass, there is also a kind of special single fire-proof glass, which refers specifically to the glass with special composition of glass substrates, rather than the glass with ordinary flat glass components. It mainly includes borosilicate fireproof glass, aluminosilicate fireproof glass, glass-ceramics fireproof glass and high-quality float glass with softening temperature higher than 800 C. Its common main characteristics are: glass softening point is higher, generally above 800 C, thermal expansion coefficient is low, under strong flame generally will not be cracked or deformed due to high temperature, especially glass-ceramics fireproof glass, besides the above characteristics, it also has high mechanical strength, flexural strength, high compressive strength and good chemical stability. Physical and mechanical properties.
2.3 by structure
Fire-proof glass can be divided into composite fire-proof glass and single fire-proof glass according to its structure.
2.3.1 composite fireproof glass
The special glass is composed of two or more layers of glass or a layer of glass and organic materials, and meets the requirements of the corresponding refractory grade. Composite fire-proof glass can be divided into composite fire-proof glass and perfusion fire-proof glass according to the manufacturing method.
The structure of composite fire-retardant glass is shown in the figure. Two or more pieces of single-layer flat float glass are bonded together with an expansion flame retardant cementing agent. Its fire protection principle: when a fire occurs, the glass will burst quickly after meeting high temperature, and its fire-proof glue interlayer will foam and expand about 10 times successively, forming a hard milky-white foam fire-proof glue board, effectively blocking the flame and isolating high-temperature harmful gas.
As shown in Figure 2, two or more sheets of single-layer float glass are sealed with frame strips around them, then fireproof liquid (such as silicone or polysulfide sealant) is poured into the filling port and cemented and sealed. The principle of fire protection is that after high temperature, the transparent gelatinous fire retardant layer in the middle of the glass will quickly harden, forming an opaque fire insulation board. While preventing the flame from spreading, it also prevents the high temperature from conducting to the back fire. Applicable to fire doors and windows, building patio, atrium, shared space, computer room fire partition wall.
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 Monolithic Fireproof Glass
Monolithic fireproof glass is a special glass which is composed of single layer glass and meets the requirements of the corresponding weatherproof grade. Monolithic fire-proof glass can keep fire-proof integrity for a certain period of time, block open fire and poisonous and harmful gases on the Fire-facing side, but it has no insulation effect. Monolithic fireproof glass is made of ordinary float glass toughened by physical and chemical treatment process, which has good temperature resistance and thermal cracking resistance. The disadvantage is that water is easy to burst when the flame is high temperature. It is suitable for exterior curtain wall, exterior window, daylighting roof, smoke-proof vertical wall, fire-proof glass frameless door and partition wall without heat insulation requirement. The standard deviation of dimension and thickness of single fireproof glass is shown in Table 2.
Since the mass production of monolithic fireproof glass in China, fireproof glass has been widely used, but several points must be paid attention to when using fireproof glass: before choosing fireproof glass, it is necessary to know the specific requirements of fireproof components composed of fireproof glass, such as fireproof, heat insulation or smoke insulation, fireproof limit requirements; monolithic and composite fireproof glass. Pouring fireproof glass can't be cut with glass knife like ordinary flat glass, it must be fixed-length processing, but composite (dry) fireproof glass can meet the requirements of cutting; when selecting fireproof glass components, in addition to considering the fireproof durability of glass, its supporting structure and elements must also meet the fireproof requirements. Needs. But in general, fireproof glass has good light transmittance.
The article originated from: Fireproof glass http://www.ba-glass.com/