Molecular Sieve is a glazed unit composed of two or more glass panes separated by spacers filled with dehydrated air or gas. The sheets are connected by a spacer, using sealants to reduce water vapor penetration. The whole unit is hermetically assembled by a secondary edge seal which gives structural robustness to the insulating glass. The spacer contains a desiccant which absorbs humidity from within the air space. Dessicants were introduced to remove the moister trapped within the IG unit. However not all desiccants work, as some do not absorb water only but also inert gas between the panes, provoking a lower thermal performance of the insulating glass. Desiccants, also known as molecular sieves, are a crucial component of each insulating glass window. These chemical substances are placed inside the IG spacers in order to perform one precise function: moisture prevention. Fogging inside the insulating glass is not only annoying but can also cause permanent staining of the glass. Moisture enters the IG unit during manufacture, and even continues to penetrate the sealant throughout the entire life of the window. To perform this function, the desiccant should have the following characteristics: water and hydrocarbons absorption, non/absorption of krypton, argon or other "thermal performance" gases, and should not contain pre-sorbed nitrogen. Briefly, the most important function of insulation glass is to reduce thermal losses, which offers many advantages: lower energy consumption, perfect transparency by reducing the incidence of condensation on the warm air side and the possibility of using larger glazed areas without increasing energy consumption.
A variety of standard bead sizes are available, such as:
- 0.5 – 1.0 mm for automatic filling systems and narrow profiles"
- 1.0 – 1.6 mm for medium sized profiles"
- 1.4 – 2.6 mm for big sized profiles and traditional filling methods"