Air from the compressor discharge flows through a bed of silica gel beads. Silica gel is also used to dry the air in industrial compressed air systems. It is common for a small compressed air system (similar to a small home aquarium pump) to be employed to circulate the air inside the waveguide over a jar of silica gel. Also, the beads of water that form and condense inside the waveguide change the characteristic impedance and frequency, impeding the signal. Excessive moisture buildup within a waveguide can cause arcing inside the waveguide itself, damaging the power amplifier feeding it. Silica gel may also be used to keep the relative humidity inside a high frequency radio or satellite transmission system waveguide as low as possible. By adding sachets of silica gel, these items can be preserved longer. Condensation may also damage other items like electronics and may speed the decomposition of chemicals, such as those in vitamin pills. In many items from leather to pepperoni, moisture encourages the growth of mold and spoilage. Some types of silica gel will 'pop' when exposed to enough water.Īpplications Desiccant See also: Desiccant Once saturated with water, the gel can be regenerated by heating to 120 ☌ (250 ☏) for two hours. Silica gel's high surface area (around 800 m²/g) allows it to absorb water readily, making it useful as a desiccant (drying agent). In World War II, silica gel was indispensable in the war effort for keeping penicillin dry, protecting military equipment from moisture damage, as a fluid cracking catalyst for the production of high octane gasoline, and as a catalyst support for the manufacture of butadiene from ethanol, feedstock for the synthetic rubber program. The substance was in existence as early as the 1640s as a scientific curiosity. Prior to that, it was used in World War I for the absorption of vapors and gases in gas mask canisters. Patrick at Johns Hopkins University, Baltimore, Maryland in 1919.

Silica gel was patented by chemistry professor Walter A.

Silica beads