Monday, February 25, 2019
How to select the right energy efficient glass?
Architectural glass is widely used in our daily life,such as glass greenhouse/conservatory-Single piece tempered glass,Glass balustrade/canopy-laminated glass,Glass curtain wall-double glazing insulated glass.But glass a good thermal conductive material,Heat conduction through the glass occurs every second causing energy loss.In buildings, 1/3 of the energy is lost through the conduction of glass. Energy efficiency has increasingly valued by architects and developers to minimize the energy consumption of the building.
1 Main parameters of glass energy efficiency evaluation
There are usually three forms of heat transfer: convection, radiation, and conduction. The parameters that measure energy propagation through glass are thermal conductivity and U value , solar transmittance, shading coefficient, SHGC(heat transfer in a stable condition).
Details here:Glass terminology
Let’s compare the normal architectural glass energy efficiency first:
| Glass | U value | Tsol% | SC | Application |
| 4mm clear tempered glass | 5.8 | 83 | 0.99 | Greenhouse Glass |
| 6mm Bronze tinted glass | 5.8 | 45 | 0.68 | Glass spandrel |
| 6+1.52+6 tempered laminated glass | 5.4 | 64 | 0.85 | Point fixed facade |
| 6+12A+6 insulated double glazing | 2.8 | 63 | 0.83 | Facade/curtain wall |
| 6 low e+12A+6 insulated double glazing | 1.6 | 30 | 0.45 | Facade/Curtain wall |
Lower U value and SC means better glass energy efficiency.
2 Energy efficient glass classification
The main energy efficient glass are tinted glass, coated glass, insulated glass, vacuum glass.
2.1 heat absorption glass-tinted glass
The energy efficiency of the heat absorbing glass is converting the light energy into heat energy when the sunlight passes through the glass.
The main color of heat absorption glass are:Green,blud,grey ,bronze and even pink glass.
2.2 coated glass
There are two types coated glass:reflective glass (also called solar control glass) and low emissivity glass.
The reflective glass is coated film on the glass surface to have a certain reflection effect.It can reflect the solar energy back into the atmosphere to block the entry of solar energy into the room.But the visible light transmittance of the glass decreases as the reflectance increases.
Ordinary flat glass has a high emissivity, usually 0.84. Low e coated glass surface radiance lower than that of ordinary glass to reduce heat loss. From single silver low e ,to double silver low e ,and then now triple silver low e coating,the more silver layers inside the coating,the lower emission will decrease U valie and Solar coefficient.
2.3 insulated glass
Insulated glass,or double glazing has a good thermal insulation because the air space between glass limit the convection and conduction heat transfer of the glass.insulating glass collect the advantages of itself and low e coated glass and playing a better role in energy conservation.
| Glass | U value | Tsol% | SC |
| 6+12A+6 | 2.8 | 63 | 0.83 |
| 6 Reflective 60+12A+6 | 2.7 | 37 | 0.52 |
| 6 Single low e 60+12A+6 | 1.8 | 33 | 0.53 |
| 6 Double low e 60+12A+6 | 1.6 | 30 | 0.38 |
| 6 Triple low e 60+12A+6 | 1.6 | 21 | 0.26 |
More low E coated glass performance data,click here:Morn-coated glass performance data
2.4 vacuum glass
Vacuum glass is currently the best energy efficient glass. Vacuum glass creates a vacuum between two sealed glass sheets to make the conduction heat between glass and glass close to zero.While for technology and costs reason,vacuum glass hasn’t been applied in large scale,in the next 20-30 years,vacuum glass will replace insulated glass once price going down.
With the continuous development of glass processing technology, more energy efficient glass appears, to minimizes energy loss, the right glass must be selected based on budget and climate,and even glass location. Only when glass is selected according to local conditions can energy-saving glass fully utilize energy efficient features.
Morn Building Materials is professional architectural glass supplier from China,with Morn’s technical support and quality assured low e coatings,we’re confident to create convenient living space with minimum thermal losses.
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tempered glass and NIS
Tempered glass is easy to self explosion. “self-explosion” is the unavoidable problem of tempered glass,In fact, tempered glass is not horrible, and the potential self-explosion of tempered glass has always been the focus of attention.
Source of nickel in glass
2.1 During the installation process of the float production line, the cleanliness of the nickel compound in the furnace has not received much attention from the float glass producers, mainly including the weld head and welding slag left after the steel structure in the furnace has been welded. Rationally speaking, it is normal for a seam to produce hundreds or even tens of thousands of small nickel compounds during welding. In fact, this also directly affects the nickel content of the float glass produced by the entire furnace. A good view of the tempered glass on the surface may shorten its service life by containing nickel sulfide greater than 60 μm.
2.2 Raw materials are also a problem that cannot be ignored. The components of float glass are quartz sand (silica sand), soda ash, thenardite, dolomite, feldspar (potassium feldspar, albite), limestone, flux, clarifier, colorant. , broken glass, etc., mainly found in silica sand, dolomite, feldspar, a trace of nickel.
The glass contains nickel sulfide crystals. NiS (nickel sulfide) has a phase transition process at 379 ° C. When the high-temperature α-NiS crystal system is changed to the low-temperature β-NiS crystal system, the volume expands by 2% to 4%. And the surface is rough. If these impurities are in the tensile stress zone of the tempered glass, volume expansion may cause spontaneous bursting.
Glass deep processing enterprises will have heat soak test on after the tempering process, effectively reducing the probability of self-explosion.
Morn -your turnkey architectural glass partner
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The defects of coated glass and solutions
Off-line(soft coated) magnetron sputter coated glass can be divided into two categories: solar control glass and low e glass. The defects ratios of them are different. The following describes the defects and solutions for these two categories of products.
1. solar control glass,solar reflective glass, common defects and solutions
Solar Control Coated Glass: A coated glass that has a certain control effect on sunlight with a wavelength of 350 to 1800 nm. It has the following drawbacks:
Pinhole: Seen from the transmission direction of the coated glass, the transparent part or all of the film layer has no point-like defects with no adhesion to the film layer; the spot: from the transmission direction of the coated glass, the dot-like defect is darker than the overall color of the film layer. .
1. solar control glass,solar reflective glass, common defects and solutions
Solar Control Coated Glass: A coated glass that has a certain control effect on sunlight with a wavelength of 350 to 1800 nm. It has the following drawbacks:
Pinhole: Seen from the transmission direction of the coated glass, the transparent part or all of the film layer has no point-like defects with no adhesion to the film layer; the spot: from the transmission direction of the coated glass, the dot-like defect is darker than the overall color of the film layer. .
1.1 Pinholes and spots are formed by the following factors, and the corresponding solutions are as follows:
1.1.1 The degree of vacuum is not enough, and the adhesion of the film layer is poor. For magnetron sputter coated glass, it should be carried out under high vacuum environment, and the base pressure of the sputtering chamber should reach 4×10-2Pa to effectively coat the coating. If the degree of vacuum is not enough, the film thickness of the batch coating will be weak, and a large amount of block-like light-transmissive areas will appear when
scrubbed with alcohol. In this case, only the base vacuum in the sputtering chamber is increased, and the coating can be performed if the degree of vacuum is enough.
1.1.2 The float glass is not fresh enough, and the adhesion to the film layer is poor. Due to the long storage time or
poor storage conditions of the original film, the surface of the float glass is seriously polluted. Although it is cleaned by deionized water before coating, the surface contamination area cannot be completely removed, and the film structure is not strong when the coating is applied. . In this situation, it is necessary to use fresh original film, and the original film of different manufacturers has different shelf life. Even the original film of the same manufacturer has a great relationship with the season and storage environment. Therefore, for different manufacturers, different seasons have different requirements for the original film, and each coating manufacturer needs to grasp it.
1.1.3 The washing machine has insufficient cleaning ability. The cleanliness of the glass surface directly affects the quality of the coating. During the entire coating production process, the quality control is in addition to the vacuum environment. The most critical step is the cleaning of the cleaning machine. Once the cleaning ability of the washing machine is insufficient, other impurities remaining on the surface of the glass may form spot or block defects. In view of this situation, in addition to improving the performance of the cleaning equipment, the most critical issue is the maintenance of the cleaning equipment, such as whether the conveying roller is clean, whether the water quality meets the requirements, whether there is foreign matter in the air knife, and whether there are too many microorganisms in the water tank. These are all factors that affect the cleaning ability of the washing machine.
1.1.4 Cover, baffle, target slag, which is also a reason for the formation of pinholes. Since the coating production process is not a single production of a variety, when changing between different products, the target materials used are different or different materials will use different power, since the cover plate and the baffle are all metal, there are certain The thermal expansion and contraction, when the thermal expansion and contraction of the sputter material covering the surface of the expansion coefficient is different from the metal, the formation of cracks, jumping off the surface of the residual glass to form pinholes, spots. In response to this situation, once the cover, the bottom plate, etc. are loaded into the vacuum chamber, it is no longer subjectively controlled by a
person. Therefore, the cover plate and the bottom plate should be thoroughly blasted before the target is placed in the vacuum chamber, and the blasting is performed to discharge the fresh section.
1.2 Scratch: Various linear scratches on the surface of the coated glass, depending on their length, width, position and distribution.
There are two factors in the formation of scratches
and different solutions for different reasons:
1.2.1 Scratch before coating. It is formed before the coating process for various reasons: such as the upper and lower sheets of each process, the transfer between each process, and the like. The formation of such scratches depends only on improving the subjective initiative of the operators and taking measures to actively prevent them.
1.2.2 Scratches during the coating. Caused by each piece of equipment in the coating process. There are obvious rules for scratches in the coating. The scratches must be along the speed direction and are very straight and straight without any inflection points. The scratches in the coating are divided into two types: film surface and glass surface scratching. Most of the film surface scratches are caused by the sinking of the molecular pump cover or the transfer to the gas separation plate. The scratch on the glass surface is mainly caused by too thick or thermal deformation of the T-plate between the bottom plate or the transfer roller. The heavier unpolished glass can be used to reduce or eliminate multiple coatings
in the sputtering chamber.
1.3 Speckle: A cloud-like, radial or streak-like defect that occurs on the surface of the film as seen from the direction of reflection of the coated glass.
There are three main reasons for the formation of markings, and there are different solutions for different reasons.
1.3.1 Cloud-like markings. Mainly due to the lack of freshness of the original film, Na+ extravasation, which is commonly known as mold. Although it has been tempered, it cannot be completely removed, so cloud-like markings are formed. In addition to ensuring the use of fresh original sheets, the expired original sheets (not too long) can be polished with polishing powder and then coated. It can improve the bonding force between the glass and the film layer to
reduce the generation of markings. Of course, the original film expires too long, and the use of polishing powder is also ineffective.
1.3.2 Radial markings, mainly due to the fact that the air knife of the washing machine is not blown clean, and radial streaks appear when the coating is applied. The solution is to adjust the angle of the air knife and ensure that there is no foreign matter in the air knife.
1.3.3 Striped markings. Mainly due to the change of local air pressure in the coating machine, especially the air leakage in the inlet and outlet chambers. Due to the wide range of local air pressure changes, only relying on the experience of each manufacturer and related equipment for leak detection, exclude the rear. Can be produced normally.
1.4 Dark channel: From the direction of reflection of the coated glass, the brightness or reflection of the surface of the film is different from the overall strip-like area, and the degree of visibility depends on the difference in brightness between them and the surrounding film. Most of the dark passages are caused by arcing or tripping of one or more of the cathodes during coating. As long as the arc is avoided and the power supply and cathode are properly operated, the dark passages will not be generated.
2 low-emission coated glass Low-emissivity coated glass, also known as low-emissivity glass, “Low-E” glass, is a coated glass with a high reflectance in the far-infrared range of 4.5μm to 25μm. As a kind of magnetron sputter coated glass, low-emission coated glass will have pinholes, streaks, scratches, dark channels and other defects like the solar control film. It has been explained in the solar control coating and will not be repeated here. However, since offline Low-E is different from sunlight film, most of them are soft films. Therefore, most of the defects are derived from the post coating process after
coating, such as post-order oxidation and post-order tempering defects.
2.1 Oxidation after coating: It means that the Low-E glass is oxidized after the coating is completed because the silver in the film is contaminated by water vapor or sulfide in the air. Mainly caused by the following reasons:
(1) The air humidity during production is too high, and the water content in the air is too high, especially during the rainy season. In the south from May to October each year is the season of easy oxidation of Low-E glass. In view of this situation, on the one hand, sufficient desiccant should be used when the glass is packaged, and on the other hand, the time for waiting for insulating production should be shortened as much as possible.
(2) When the sweat is applied to the glass on the glove, the sweat contains a large amount of sulfide, which will react with the silver in the Low-E glass to form black silver sulfide, thereby forming oxidation. . We have experimented with the formation of oxidation in the shortest 1 hour of LoW-E glass that has been adhered to by sweat. Therefore, on the one hand, the gloves are kept dry, and on the other hand, the Low-E glass touched by the sweat is immediately cleaned and the waiting time for hollow production is shortened as much as possible.
(3) Insulated glass is not handled properly. Improper handling of insulated glass, such as gas leakage, molecular sieve leakage, etc., may cause oxidation of the Low-E glass after the insulating, especially the butyl sealant is not fully filled and the molecular sieve is a fatal threat to the Low-E glass. Therefore, how to improve the quality of insulated glass is a key factor to avoid the 2.2 Post tempering defects: refers to a series of defects in the subsequent processing of tempered Low-E glass. Since the tempered Low-E glass has multiple processes after the coating is completed, the processing flow is as follows: :
The processing of each process may cause damage to the Low-E glass. In the production process, the longer the cycle time, the greater the probability of defects. In addition, since the surface resistances of different Low-E products are different, the heat transfer coefficient is also different. Therefore, the selection of a suitable tempering process is essential to improve the quality of the coating after Low-E glass tempering.
Therefore, in addition to the coating process, the control of the temperable Low-E must be done in accordance with the corresponding measures to reduce the occurrence of defects.
3 Conclusion
Whether it is a solar control film or a low-emission coated glass, as long as the cause of the defect formation is found, it is possible to reduce the occurrence of defects.
1.1.1 The degree of vacuum is not enough, and the adhesion of the film layer is poor. For magnetron sputter coated glass, it should be carried out under high vacuum environment, and the base pressure of the sputtering chamber should reach 4×10-2Pa to effectively coat the coating. If the degree of vacuum is not enough, the film thickness of the batch coating will be weak, and a large amount of block-like light-transmissive areas will appear when
scrubbed with alcohol. In this case, only the base vacuum in the sputtering chamber is increased, and the coating can be performed if the degree of vacuum is enough.
1.1.2 The float glass is not fresh enough, and the adhesion to the film layer is poor. Due to the long storage time or
poor storage conditions of the original film, the surface of the float glass is seriously polluted. Although it is cleaned by deionized water before coating, the surface contamination area cannot be completely removed, and the film structure is not strong when the coating is applied. . In this situation, it is necessary to use fresh original film, and the original film of different manufacturers has different shelf life. Even the original film of the same manufacturer has a great relationship with the season and storage environment. Therefore, for different manufacturers, different seasons have different requirements for the original film, and each coating manufacturer needs to grasp it.
1.1.3 The washing machine has insufficient cleaning ability. The cleanliness of the glass surface directly affects the quality of the coating. During the entire coating production process, the quality control is in addition to the vacuum environment. The most critical step is the cleaning of the cleaning machine. Once the cleaning ability of the washing machine is insufficient, other impurities remaining on the surface of the glass may form spot or block defects. In view of this situation, in addition to improving the performance of the cleaning equipment, the most critical issue is the maintenance of the cleaning equipment, such as whether the conveying roller is clean, whether the water quality meets the requirements, whether there is foreign matter in the air knife, and whether there are too many microorganisms in the water tank. These are all factors that affect the cleaning ability of the washing machine.
1.1.4 Cover, baffle, target slag, which is also a reason for the formation of pinholes. Since the coating production process is not a single production of a variety, when changing between different products, the target materials used are different or different materials will use different power, since the cover plate and the baffle are all metal, there are certain The thermal expansion and contraction, when the thermal expansion and contraction of the sputter material covering the surface of the expansion coefficient is different from the metal, the formation of cracks, jumping off the surface of the residual glass to form pinholes, spots. In response to this situation, once the cover, the bottom plate, etc. are loaded into the vacuum chamber, it is no longer subjectively controlled by a
person. Therefore, the cover plate and the bottom plate should be thoroughly blasted before the target is placed in the vacuum chamber, and the blasting is performed to discharge the fresh section.
1.2 Scratch: Various linear scratches on the surface of the coated glass, depending on their length, width, position and distribution.
There are two factors in the formation of scratches
and different solutions for different reasons:
1.2.1 Scratch before coating. It is formed before the coating process for various reasons: such as the upper and lower sheets of each process, the transfer between each process, and the like. The formation of such scratches depends only on improving the subjective initiative of the operators and taking measures to actively prevent them.
1.2.2 Scratches during the coating. Caused by each piece of equipment in the coating process. There are obvious rules for scratches in the coating. The scratches must be along the speed direction and are very straight and straight without any inflection points. The scratches in the coating are divided into two types: film surface and glass surface scratching. Most of the film surface scratches are caused by the sinking of the molecular pump cover or the transfer to the gas separation plate. The scratch on the glass surface is mainly caused by too thick or thermal deformation of the T-plate between the bottom plate or the transfer roller. The heavier unpolished glass can be used to reduce or eliminate multiple coatings
in the sputtering chamber.
1.3 Speckle: A cloud-like, radial or streak-like defect that occurs on the surface of the film as seen from the direction of reflection of the coated glass.
There are three main reasons for the formation of markings, and there are different solutions for different reasons.
1.3.1 Cloud-like markings. Mainly due to the lack of freshness of the original film, Na+ extravasation, which is commonly known as mold. Although it has been tempered, it cannot be completely removed, so cloud-like markings are formed. In addition to ensuring the use of fresh original sheets, the expired original sheets (not too long) can be polished with polishing powder and then coated. It can improve the bonding force between the glass and the film layer to
reduce the generation of markings. Of course, the original film expires too long, and the use of polishing powder is also ineffective.
1.3.2 Radial markings, mainly due to the fact that the air knife of the washing machine is not blown clean, and radial streaks appear when the coating is applied. The solution is to adjust the angle of the air knife and ensure that there is no foreign matter in the air knife.
1.3.3 Striped markings. Mainly due to the change of local air pressure in the coating machine, especially the air leakage in the inlet and outlet chambers. Due to the wide range of local air pressure changes, only relying on the experience of each manufacturer and related equipment for leak detection, exclude the rear. Can be produced normally.
1.4 Dark channel: From the direction of reflection of the coated glass, the brightness or reflection of the surface of the film is different from the overall strip-like area, and the degree of visibility depends on the difference in brightness between them and the surrounding film. Most of the dark passages are caused by arcing or tripping of one or more of the cathodes during coating. As long as the arc is avoided and the power supply and cathode are properly operated, the dark passages will not be generated.
2 low-emission coated glass Low-emissivity coated glass, also known as low-emissivity glass, “Low-E” glass, is a coated glass with a high reflectance in the far-infrared range of 4.5μm to 25μm. As a kind of magnetron sputter coated glass, low-emission coated glass will have pinholes, streaks, scratches, dark channels and other defects like the solar control film. It has been explained in the solar control coating and will not be repeated here. However, since offline Low-E is different from sunlight film, most of them are soft films. Therefore, most of the defects are derived from the post coating process after
coating, such as post-order oxidation and post-order tempering defects.
2.1 Oxidation after coating: It means that the Low-E glass is oxidized after the coating is completed because the silver in the film is contaminated by water vapor or sulfide in the air. Mainly caused by the following reasons:
(1) The air humidity during production is too high, and the water content in the air is too high, especially during the rainy season. In the south from May to October each year is the season of easy oxidation of Low-E glass. In view of this situation, on the one hand, sufficient desiccant should be used when the glass is packaged, and on the other hand, the time for waiting for insulating production should be shortened as much as possible.
(2) When the sweat is applied to the glass on the glove, the sweat contains a large amount of sulfide, which will react with the silver in the Low-E glass to form black silver sulfide, thereby forming oxidation. . We have experimented with the formation of oxidation in the shortest 1 hour of LoW-E glass that has been adhered to by sweat. Therefore, on the one hand, the gloves are kept dry, and on the other hand, the Low-E glass touched by the sweat is immediately cleaned and the waiting time for hollow production is shortened as much as possible.
(3) Insulated glass is not handled properly. Improper handling of insulated glass, such as gas leakage, molecular sieve leakage, etc., may cause oxidation of the Low-E glass after the insulating, especially the butyl sealant is not fully filled and the molecular sieve is a fatal threat to the Low-E glass. Therefore, how to improve the quality of insulated glass is a key factor to avoid the 2.2 Post tempering defects: refers to a series of defects in the subsequent processing of tempered Low-E glass. Since the tempered Low-E glass has multiple processes after the coating is completed, the processing flow is as follows: :
The processing of each process may cause damage to the Low-E glass. In the production process, the longer the cycle time, the greater the probability of defects. In addition, since the surface resistances of different Low-E products are different, the heat transfer coefficient is also different. Therefore, the selection of a suitable tempering process is essential to improve the quality of the coating after Low-E glass tempering.
Therefore, in addition to the coating process, the control of the temperable Low-E must be done in accordance with the corresponding measures to reduce the occurrence of defects.
3 Conclusion
Whether it is a solar control film or a low-emission coated glass, as long as the cause of the defect formation is found, it is possible to reduce the occurrence of defects.
Related News
Light pollution of glass curtain wall
The light pollution of the glass curtain wall refers to the use of coated glass on the curtain wall of high-rise buildings. When direct sunlight and skylight are irradiated onto the glass surface, the specular reflection (ie, specular reflection) of the glass. And the resulting reflected glare.
Light pollution is the murderer of accidental traffic accidents. A glass walled building stands like a huge mirror with a width of tens of meters and a height of nearly 100 meters. It reflects the traffic conditions and traffic lights (even multiple reflections). The reflected light enters the car at high speed, which will cause sudden temporary blindness and visual illusion, which will cover the driver’s vision in an instant, or make him feel dizzy and seriously endanger the visual function of pedestrians and drivers. The glass curtain walls built around the residential area will reflect the surrounding buildings. According to optical experts, the reflected light of mirrored building glass is stronger than that of sunlight, and its reflectivity is as high as 82% to 90%. The light is almost completely reflected, which greatly exceeds the range that the human body can bear. In the summer, the sun is reflected into the living room. The strong glare is the most damaging to the original good atmosphere in the room. It also raises the room temperature by an average of 4 °C to 6 °C. People who work and live in a white bright and polluted environment for a long time may easily lead to decreased vision, dizziness, insomnia, palpitations, loss of appetite and depression, and other symptoms of neurasthenia, which may cause changes in normal physiological and psychological conditions. Long-term will induce certain diseases. Therefore, the State Environmental Protection Administration has received complaints about light pollution all over the country every year, which has attracted the attention of relevant state departments.
Light pollution is the murderer of accidental traffic accidents. A glass walled building stands like a huge mirror with a width of tens of meters and a height of nearly 100 meters. It reflects the traffic conditions and traffic lights (even multiple reflections). The reflected light enters the car at high speed, which will cause sudden temporary blindness and visual illusion, which will cover the driver’s vision in an instant, or make him feel dizzy and seriously endanger the visual function of pedestrians and drivers. The glass curtain walls built around the residential area will reflect the surrounding buildings. According to optical experts, the reflected light of mirrored building glass is stronger than that of sunlight, and its reflectivity is as high as 82% to 90%. The light is almost completely reflected, which greatly exceeds the range that the human body can bear. In the summer, the sun is reflected into the living room. The strong glare is the most damaging to the original good atmosphere in the room. It also raises the room temperature by an average of 4 °C to 6 °C. People who work and live in a white bright and polluted environment for a long time may easily lead to decreased vision, dizziness, insomnia, palpitations, loss of appetite and depression, and other symptoms of neurasthenia, which may cause changes in normal physiological and psychological conditions. Long-term will induce certain diseases. Therefore, the State Environmental Protection Administration has received complaints about light pollution all over the country every year, which has attracted the attention of relevant state departments.
Light pollution is produced under the following specific conditions: (1) the use of large areas of high reflectivity coated glass; (2) in a specific direction and at a specific time; (3) the degree of light pollution and the direction, position and height of the glass curtain wall Have a close relationship. Because the human’s angle of view has the greatest influence within an angle of ±15 degrees around 2 meters, the intensity of light reflection is inversely proportional to the square of the distance from the reflector to the human eye.
In recent years, governments and relevant academic groups have attached great importance to the issue of light pollution, and have successively published a series of technical documents, standards and decrees to control light pollution. China has also attached great importance to the problem of curtain wall construction. In 1996, the regulations on the technical standards of curtain wall engineering and the provisional regulations on strengthening the management of building curtain wall projects were successively introduced, which made the quality of control curtain wall projects have a legal basis. According to their actual situation, various localities have also taken some corresponding feasible measures.
The emergence of the problem of light pollution does not mean that the glass curtain wall should not be done, but how to do it well. At present, the development of high-tech has developed the material of curtain wall from single glass to steel plate, aluminum plate, alloy plate, marble plate, enamel sintered plate, etc. Through reasonable design, the glass curtain wall and the curtain wall of steel, aluminum, alloy and other materials are combined. Together, it not only makes the high-rise buildings more beautiful, but also reduces the light pollution caused by the reflection of the curtain wall more effectively. It can further reduce the self-weight of the high-rise buildings and give full play to the advantages of the curtain wall building materials.
In recent years, governments and relevant academic groups have attached great importance to the issue of light pollution, and have successively published a series of technical documents, standards and decrees to control light pollution. China has also attached great importance to the problem of curtain wall construction. In 1996, the regulations on the technical standards of curtain wall engineering and the provisional regulations on strengthening the management of building curtain wall projects were successively introduced, which made the quality of control curtain wall projects have a legal basis. According to their actual situation, various localities have also taken some corresponding feasible measures.
The emergence of the problem of light pollution does not mean that the glass curtain wall should not be done, but how to do it well. At present, the development of high-tech has developed the material of curtain wall from single glass to steel plate, aluminum plate, alloy plate, marble plate, enamel sintered plate, etc. Through reasonable design, the glass curtain wall and the curtain wall of steel, aluminum, alloy and other materials are combined. Together, it not only makes the high-rise buildings more beautiful, but also reduces the light pollution caused by the reflection of the curtain wall more effectively. It can further reduce the self-weight of the high-rise buildings and give full play to the advantages of the curtain wall building materials.
Glass plays a key role in the glass curtain wall. The glass type of the glass curtain wall should be carefully selected according to some parameters of the glass, and the glass with glare reduction performance should be selected. These parameters include the light and climate parameters of the building site, the transmission number of visible light, Reflection coefficient, transmission coefficient, reflection coefficient and absorption coefficient for sunlight, as well as heat transmission coefficient, thermal expansion coefficient, and thickness, maximum size, weight, and wind resistance. It is well known that glass has transmission, absorption and reflection properties for light. The glass curtain wall uses different types of glass according to these characteristics. The glass used for the glass curtain wall generally has transparent glass, colored glass, heat absorbing glass, coated glass, coated glass, laminated glass, and photochemical glass. The advantages and disadvantages of each of them can be seen in the glass used on these glass walls.
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The application of capillary tube in insulated glass
Generally, both the production and installation of the insulated glass are in the same or very similar latitude range. Under the same conditions, the air pressure in the insulated glass is always the same as the external pressure. But when the insulating glass is made at low latitudes such as sea level and then installed at a higher latitude, if we still simply assume that the pressure inside the insulating glass is still the same as the external pressure between the two places, it cannot explain why the two pieces of insulated glass deflect outward, visually deformed, and even the l burst. This is because the pressure inside and outside the insulating glass when the insulating glass is produced is larger than the pressure at the time of mounting at a high latitude. If the pressure difference is too large and exceeds the strength of the glass itself, the hollow glass may be broken/or the structural rubber of the insulating glass may be broken, resulting in premature failure of the sealing of the insulated glass. The traditional way to solve this problem is to install a breathing tube or capillary tube on the sealing edge of the insulating glass. The function of the breathing tube and capillary tube is to continuously adjust the difference between the pressure in the air layer of the insulated glass and the external atmospheric pressure as the height changes, so that it achieves dynamic equilibrium. Previously, the approach adopted was to install a breathing tube when the height of the hollow glass window in transport exceeded 5,000 feet (about 1524 meters).
Keep in mind that the use of a “snorkel” with a large internal diameter requires sealing at the final installation to prevent premature failure of the insulating glass seal. The disadvantage of this approach is that the overall performance of the insulating structure of the insulating glazing depends on the local door and window installer, rather than in the hands of the producer of the insulating glass window. Therefore, no matter how good the quality of the insulating glass is, there is a problem if the snorkel is not sealed at the end of the installation. One way to solve the problem is to replace the breathing tube with a capillary. It can be seen from Table 1 that the inner diameter of the capillary is smaller (about 1/10 of the breathing tube) and the tube is longer than the breathing tube, so that even if the capillary is not sealed, the whole of the hollow glass after installation at a high latitude can be ensured. performance. Despite this, so far, there is no laboratory data to support this statement (the practice). In fact, there is still debate in the North American insulating glass industry about the durability and longevity of insulating glass with capillary or snorkel installed; even if the insulating glass with capillary is tested by ASTM773/774, it does not mean that the actual sealing life can be reached. 5 years.
Evaluation of the snorkel and capillaries
Due to the use of argon to fill the insulating glass, one has to rethink the height limit problem seriously. The outside air is exchanged with the gas in the hollow glass through the breathing tube, and as a result, the concentration of the inert gas therein is greatly reduced within a few months after the installation of the insulating glass. When the hollow glass window filled with argon gas is transported to the mountains, in order to install the argon-filled insulating glass as much as possible in the latitude, without reducing the sealing integrity of the insulating glass, the breathing should be avoided as much as possible. tube. The durability of the insulating glass using the butyl rubber and the silicone rubber double-pass sealing structure has been demonstrated to have excellent structural integrity. In most cases, the strength of the glass itself becomes a factor in the highest latitude limit of the insulating glass. Two different cases of height limits: the altitude limit at which the insulating glass can be installed and the height limit in the transport of insulating glass.
Insulating glass at the height limit of mountain transportation
In this case, when the cargo truck is driven by the insulating glass through the mountain road, the time of the air pressure change is relatively short. At this time, since the surface of the hollow glass on the vehicle is strong, the risk of bursting is small. If the insulating glass is installed in the window frame, the glass can flex freely outward, and when it is transported to a low latitude, the glass returns to the normal position. If only the insulating glass is transported (when the glass is only twisted together), the glass deflects outwards so that the glass “scratches” each other in contact with each other. In this case, special packaging should be used to ensure that there is enough space between the insulating glass to flex outwards to avoid bursting.
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How to improve the yield of tempered glass?
Tempered glass is widely visible in everyday life. There are more and more glass processing enterprises producing tempered glass. How to effectively improve the yield of tempered glass is a problem that all glass deep processing enterprises have always been concerned about.
To improve the yield of tempered glass, the following must be done:
First, the glass must be edging before tempering. The quality of glass edging plays a decisive role in the rate of tempering. When the glass is cut, small, very fine cracks are left on the edges, which are almost invisible to the naked eye. There are two functions of edging, one is aesthetic, and the other is to not break easily during tempering and improve the yield of tempered glass.
Second, adjust the process parameters of tempering. The tempering process parameters are mainly the heating temperature, the heating time, the wind pressure time of the tempering cooling and the tempering cooling time. The temperature of the tempering is inversely proportional to the heating time, and the higher the temperature, the shorter the heating time. However, when we temper the thick glass of 12mm or more, if the furnace temperature is too high, it is easy to fry the furnace inside the furnace. Of course, there are many reasons for the fryer, and the furnace temperature setting is too high. It is recommended that the glass of 12 mm or more be set to a temperature of about 665 ° during tempering, and the heating time should be appropriately extended. A reasonable heating time needs to be selected after the temperature is determined. In general, the heating time per millimeter is about 40 seconds. However, it is necessary to increase the heating time by 10% when tempering the glass of the large layout, and increase the heating time by 10% when tempering the perforated and angled glass. Dialectical mastery of heating time and heating temperature is very important, and is also the key to improving the yield of tempered glass.
Third, the importance of uniform heating of the glass. The glass is actually a cube with 4 sides and 6 sides. The heating of the upper and lower sides of the glass is relatively slow. When tempering large-format glass, the middle of the glass tends to be the slowest in heat, and sometimes the tempered glass forms a pot shape (especially a large-format glass close to a square). It is caused by the excessive heating of the edge and the slow heating in the middle, that is, after the heating is completed, the temperature of the edge of the glass is much higher than the temperature in the middle of the glass. If the glass of the large layout is heated evenly, it is better to set the temperature of the furnace to a heating curve (lateral) where the temperature is higher than the set temperature by 10 degrees and the edge temperature is lower than the set temperature by 10 degrees. The tempered glass thus has a uniform degree of uniformity and uniformity.
Fourth, the hole, the angle of the glass. Generally speaking, if tempered glass needs to be punched, you need to pay attention to the following points:
- The holes diameter should be greater than or equal to the thickness of the glass;
- The distance between the edge of the hole and the edge of the glass is greater than or equal to twice the thickness of the glass;
- The distance between the two holes, the distance between the edge of the hole and the edge of the hole is greater than or equal to twice the thickness of the glass. If you can’t reach this requirement and you have to punch holes, you can solve it by slotting. Without affecting the use and aesthetics, use a cutter to cut a small gap between the glass edge and the hole at the edge of the glass. This is the best solution to solve some of the problems that do not meet the punching requirements and must be punched.
- China Morn-Your Turnkey Architectural Glass Partner
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