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THE ORCBS > Biological Safety > Programs & Guidelines > Biosafety Manual >
Class II Biological Safety Cabinet This is a ventilated cabinet for personnel, product and environmental protection which provides inward airflow and HEPA-filtered supply and exhaust air. The Class II cabinet has four designs depending on how much air is recirculated and/or exhausted and if the BSC is hard-ducted to the ventilation system or not. Class II cabinets may be of use with low to moderate risk biological agents, minute quantities of toxic chemicals, and trace quantities of radionuclides; however, care must be exercised in selecting the correct Class II cabinet design for these purposes. Class II Type A1 Biological Safety Cabinet Air from the Class IIA1 BSC exhaust can be recirculated to the room or discharged to the outside of the building through a thimble connection to a dedicated duct or through the building exhaust system. A connection to a ducted exhaust system also allows some BSCs to be used for work with volatile radionuclides and volatile toxic chemicals (Table 3). Class II Type A2 Vented to the Outside, B1 and B2 Biological Safety CabinetsClass IIA2 vented to the outside, IIB1 and IIB2 BSCs are variations of the Class IIA1. Each variation allows the BSC to be used for specialized purposes (see Table 3). These BSCs differ from one another in several aspects: the air intake velocity through the front opening; the amount of air recirculated over the work surface and exhausted from the cabinet's exhaust system, which determines whether air from the cabinet is exhausted to the room, or to the outside, through a dedicated exhaust system or through the building exhaust and the pressure arrangements (whether cabinets have biologically contaminated ducts and plenums are surrounded by negative-pressure ducts and plenums). |
Safety Equipment: Biological Ssafety Cabinets (BSCs)
