Types of Class II Biosafety Cabinets
Class II biological safety cabinets are primary engineering controls typically used for microbiological studies, cell culture, pharmaceutical procedures and toxicology.
BSC classifications and standards for the United States are set by NSF International (formerly the National Sanitation Foundation). NSF defines four types of Class II cabinets (A1, A2, B1 and B2) that are distinguished by differences in airflow patterns and velocities, HEPA air filter positions, ventilation rates and exhaust methods.
The classification system has changed throughout the years, and the following overview refers to the 2011 NSF/ANSI 49 2011 manual.
Fonte: Baker