Many people have fallen into an erroneous zone: the insulating glass is filled with argon to prevent the insulating glass from fogging. In fact, this statement is incorrect!
Why is this statement incorrect? We explained from the production process of hollow glass that the causes leading to the fogging of hollow glass are nothing more than air leakage due to seal failure, or moisture in the hollow cavity cannot be completely absorbed by the desiccant due to intact seal. Under the effect of indoor and outdoor temperature difference, moisture in the cavity condenses on the glass surface to generate condensation phenomenon. The so-called condensation is just like the ice cream we eat at ordinary times, because the moisture in the air condenses on the outer surface of the ice cream package ( i.e. temperature difference effect ). Therefore, the hollow glass will not be fogged ( dewing ) unless the following points are done:
1. The first sealant, butyl rubber, must be uniform and continuous. This sealant is connected between the aluminum spacer and the glass. Butyl rubber is selected because it has water vapor permeability and air permeability unmatched by other adhesives ( see the table below ). It can be said that more than 80% of the anti-water vapor permeation tasks of the insulating glass are on this glue. If the sealing is not good, the insulating glass leaks air, and no matter how many other working glasses are used, fog will occur.
2. The second sealant, due to the consideration of UV protection, now AB two-component silicone adhesive is mostly used for door and window glass. Although silicone adhesive has poor water vapor tightness, it can play an auxiliary sealing, bonding and protection role.
3. The first two sealing jobs have been completed. The next job is the hollow glass desiccant 3A molecular sieve. The 3A molecular sieve only absorbs water vapor and does not absorb any other gas. Sufficient 3A molecular sieve will absorb water vapor in the hollow cavity of the hollow glass and keep the gas dry, so that no fog and condensation will occur. Hollow glass of good quality will not have condensation even in an environment of minus 70 degrees.
4. Fogging of insulating glass is also related to the production process. Aluminum spacer bars filled with molecular sieves should not be placed for too long before lamination, especially in rainy season or in humid weather like spring in Guangdong, more attention should be paid to controlling lamination time. Because the insulating glass placed for too long will absorb the water in the air, the molecular sieve saturated with water will lose its adsorption effect, and fog will occur after the sheets are combined because it cannot absorb the water in the hollow cavity. In addition, the filling amount of molecular sieve is also directly related to fogging.
5. Apart from the above points, it is also very important to use spacer bars. Aluminum spacer bars and warm edge spacer bars are more common now, but are they different?
Infrared Contrast Diagram of Aluminum Strip and Warm Edge Spacer in Doors and Windows
As can be seen from the above figure, the edge temperature of doors and windows with aluminum spacers is obviously lower than that of doors and windows with warm edge spacers. Therefore, dew condensation will still occur in doors and windows with aluminum spacers, and this " embarrassing" phenomenon can be well avoided by using warm edge spacers. At present, passive low-energy buildings have been greatly promoted in China. You will find that the insulating glass products for outer windows used in these low-energy buildings basically adopt warm edge spacers. With the further development of building energy conservation, there will be a greater market for the application of warm edge spacers in insulating glass for energy-saving doors and windows.
