Air from the BSC is exhausted through a HEPA filter and either into the room or through ducting to the outside via a canopy connection. Only when the BSC is ducted to the outside does it meet the requirements of the former Class II, Type B3 BSC.
Airflow in the BSC
Air flows from the room into the front grill of the BSC but does not flow across the work zone (red arrow). In the cabinet, the air is circulated through a fan (purple arrow) and sent to the filters (yellow arrow).
Airflow in the BSC
In the cabinet, the air is circulated through a fan (purple arrow) and sent to the filters (yellow arrow). Air is then filtered through high efficiency filters (blue arrows) and is either exhausted or circulated to the work zone. Slow, steady operator movements ensure containment within the BSC.
BSCs use vertical laminar airflow to create a barrier to airborne particles, such as microorganisms. They use High Efficiency Particulate Air (HEPA) filters to clean air going into the work area and out to the environment. The air in most BSCs is recirculated over the work area through the HEPA filter.
The cabinet has a minimum inflow speed of 100 linear feet per minute at the opening on its face. The air supply passes through a HEPA filter for particulate-free air, drawn by a blower. Air circulates and is drawn through an exhaust HEPA filter to be vented out; 100 percent of air is exhausted.
