Sodium silicate, a porous but granular shape of silica, is used to make silica gel synthetically. It's used as a desiccant or moisture adsorbent to regulate humidity levels locally and prevent products from degrading. Self-indicting style desiccants, such as silica gel blue crystals, are produced by infusing white silica crystals in cobalt chloride. These crystals are strong by default and are held in a breather because of their ability to withstand a lot of moisture.
A transformer's breathing mechanism involves the passage of air in and out due to thermal contractions and expansions caused by the oil within it. The air pressure within the transformer is regulated by this mechanism, which is crucial. However, moisture and dust penetrate the transformer during the breathing process, allowing the oil's dielectric strength to shift, disrupting the transformer's proper operation and, in some situations, contributing to failure. As a result, it is important that the air inside the transformer be free of dust and humidity.
This is why a desiccant or indicating silica gel blue is needed for the breather transformer. Semi-transparent and glassy silica gel blue crystals. Because of the cobalt in these beads or crystals of silica gel blue, they are dark blue in colour while they are free of humidity. Their hue changes from dark blue to light blue, then gradually to pink as the humidity level grows around them, signalling that the humidity level has reached its highest and they need to be regenerated or replaced.
It's fully dried if it's dark blue Silica Gel. The light blue colour suggests 15 percent moisture absorption, while the pink colour indicates that it is completely saturated, having absorbed moisture equal to 30 percent to 40 percent of its weight. The fact that silica gel can be reheated indicates that it can be regenerated.
Both small pouches and bulk silica gel blue beads are available. However, silica blue crystals are typically only available in bulk sizes. Mesh sizes range from 9-12mm(1-2), 6-8mm(3-4), 4-6mm(5-8), 2-4mm(9-16), and 1-2mm (16-30). The larger mesh sizes, such as 1-2 Mesh, 3-4 Mesh, and 5-8 Mesh, are used as silica gel Breathers in transformers, whereas the smaller mesh sizes, such as 9-16 Mesh, 16-30 Mesh, and 30-60 Mesh, are used as desiccants absorbents in pouches. The use of small particles as desiccants is important because the small distance between them prevents humidity from interfering with the existence of the silica gel blue crystals.
