Silica gel is a spherical bead consisting of 97% silica and 3% alumina with a highly porous surface and a strong affinity for adsorbing water. Silica gel is also applied as a selective adsorbent for a wide-range of hydrocarbons, C02, siloxanes, sulfur, and many other compounds. Because silica gel fractures in the presence of liquid water, it is often protected with a pre-bed of activated alumina. In air and gas drying applications, dew points of -40°F and lower can be achieved with silica gel.