Clean Room Systems
In clean room systems, airborne contaminants are reduced by fans, filters and other control systems. Contaminants brought into enclosures by humans are reduced through the use of clean suits (also known as bunny suits) and pre-entry decontamination by air jets. The design of the enclosures themselves also contributes to the level of decontamination a clean room can achieve. Portable and modular clean rooms can be easily moved and assembled, and when combined with proper filtration equipment and the use of clean suits, they can reach fairly low levels of decontamination. Permanent clean rooms, though, can achieve extremely high levels of decontamination, and are for this reason the enclosures of choice for the most sensitive biotechnology and nanotechnology research efforts.
US FED STD 209E standards dictate the acceptable level of particulate presence in an enclosure. The standards are based on the number of 0.5 micrometer-sized particles per cubic foot. Class 1 clean rooms adhere to the strictest standard: no more than one 0.5 micrometer-sized particle per cubic foot of atmosphere within the enclosure. An advanced complex of equipment including particle-counting, light-scattering instrumentation, high-efficiency particulate air (HEPA) filters, personnel decontamination air jets and other equipment must work in concert in order to reach such an extremely low level of contaminants. From there, the class numbers increase by multiples of ten; their class numbers reflect the volume of acceptable particulates per square foot.
Class 100, for example, allows 100 0.5 micrometer-sized particles per square foot. Normal, unfiltered air would be Class 1,000,000 if it were classified according to that metric. Walls and working surfaces within permanent clean rooms are often made of steel, stainless steel, acrylics and polycarbonates because of their non-reactivity and non-porosity. They are also easily sterilized and don't degrade when exposed to cleaning chemicals, though there are some exceptions. Temporary clean rooms more commonly feature transparent or translucent plastic for their wall materials; those plastics are usually chosen for their non-porosity and ease of cleaning as well.
