Class II cabinet
From Wikipedia, the free encyclopedia
A Class II Cabinet or microbiological safety cabinet is a piece of laboratory equipment that provides a safe working area for people handling material potentially contaminated with pathogens.
The principle of operation involves using a fan mounted in the top of the cabinet to draw a curtain of sterile air over the products that are being handled. The air is then drawn underneath the work surface and back up to the top of the cabinet where it passes through filters (HEPA filters) that are capable of removing harmful bacteria and viruses. Seventy percent of the air is continuously recirculated in this way, while 30 percent is exhausted through another HEPA filter in the top of the cabinet. The air that is exhausted is made up by air being drawn into the front of the cabinet underneath the worksurface. The air being drawn in acts as a barrier to potentially contaminated air coming back out to the operator.
"Class II" refers to the NSF classification of this type of cabinet. Subdivisions within this class based on airflow patterns inside the cabinet and acceptable uses include A1, A2, B1, B2. Older pre-2002 NSF designations include A/B3 and others.
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