Air Shower Functions
Air showers are generally constructed from cleanroom-compatible steel or plastic materials and feature electronically-powered blowers, filters and high-pressure jet nozzles, the latter being incorporated into the walls and ceiling of the chamber.  Air, at velocities of 3,000 to 7,000 feet-per-minute (FPM), continuously streams from the jet nozzles for 30-45 seconds, effectively removing loose particulate matter. Personnel inside the enclosure will lift their arms and turn their bodies for uniform exposure to the air streams, a procedure usually specified in protocol. Air currents from the jets create shearing and flapping forces, which lift and remove contaminants from both flat surfaces and the creases of garments. HEPA filtration within the air shower is capable of removing 99.97% of particles greater than 0.3µm diameter.
Air is channeled within the air shower using a closed-loop system, where it is continuously re-circulated. Air is forced through a motorized filter/blower module into a large plenum, then into the shower through jet nozzles. Particle-laden, contaminated air is routed out of the shower compartment through floor vents and returned to the filtration unit. This process ensures that only decontaminated air is used to remove particulates from personnel and other equipment, such as supply carts.
Often, air showers are equipped with air ionizers to reduce static electricity, as large volumes of high-velocity air create electric charges. Since laboratory equipment, electronic measuring instruments and many hi-tech manufactured goods can often be damaged by electrostatic discharge, ionizers are essential in rendering material surfaces electrically neutral prior to entering the cleanroom.