Clean rooms are spaces maintained free of dust and other airborne particles as well as bacteria and other contaminants. They’re used in research settings in the study of everything from biological specimens and particle experiments in physics to the construction of electronic components. Some uses require a greater degree of cleanliness, and the International Standard of Organization developed standards for clean-room classification. A Class 8 Clean Room is one of the lowest levels of clean-room environments, and has relatively lax standards of environmental control.
An ISO Class 8 clean room has the same stringency standards as a US FED STD 209E Class 100,000 clean room, and is about 100,000 times cleaner than natural air. Both measure the concentration of airborne particles, and require less than 29,300 particles sized larger than 5 micrometers per cubic meter of air, no more than 832,000 particles sized less than 1 micrometer per cubic meter of air and fewer than 3.52 million particles sized less than 0.5 micrometer per cubic meter of air. Class 8 clean rooms don’t regulate particles smaller than 0.5 micrometers.
A clean room must provide air circulating at all times. ISO standards require vents and filtration systems to cycle the entire volume of air in a clean room in a one-hour period. HEPA filters remove 99.97 per cent of particles larger than 0.3 micrometers, and need to be used to keep circulated air free of contaminants. In addition to filtration systems, a clean room’s circulation system must maintain a positive air pressure in relation to the outside environment so that air rushes out when the door is opened, blowing outside contaminants away from the room.
Construction and Outfitting
In order to keep contaminants from settling in a clean room, it must be constructed without surfaces for dust to collect. This includes building perfectly level floors, adding light fixtures that are sealed and smooth on the clean-room side and eliminating light switches and other fixtures. In addition, only stainless-steel or plastic workstations and furniture should be used to prevent flaking of paint and dust created by the degradation of upholstery and foam cushions.
Construcation and Outfitting
As with any level of clean room, anyone entering a clean room must wear a clean suit to trap dust and other contaminants that may be carried in on clothes and shoes into the room. Hair and exposed skin must be covered to keep biologically degraded contaminants at a minimum.