What happened to the Class II Type A/B3 Biosafety Cabinet?

The Class II Type A/B3 Biosafety Cabinet has been replaced by the Class II Type A2 BSC

NSF International modified NSF/ANSI Standard 49 in 2002 to replace the Type A/B3 biosafety cabinet configuration with the Type A2.

A Type A2 cabinet’s exhaust can be recirculated to the room or canopy connected to an external exhaust duct so that both of the configurations of the Type A/B3 can be met. The design of Type A2 cabinets has been considered by NSF International to be an engineering improvement.

NSF requires that all biosafety cabinets of Type A/B3, which were manufactured prior to 2002, must be converted to Type A2 cabinets with thimble/canopy connection. Furthermore, in 2010, NSF required all canopy connected A2s to be outfitted with an airflow detection system – to include an audio/visual alarm.

If you have more questions about Biological Safety Cabinets, please feel free to contact me directly. Or to teach yourself what you absolutely need to know about biological safety cabinets, learn more at

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