WHAT IT IS…
Biological safety cabinets are work stations designed in order to make safe the manipulations on potentially hazardous biological agents, such as virus or bacteria.
There’s currently no israeli standard about B.S.C. so the professionals involved with them got used to refer to the de facto american standard : the National Sanitation Foundation standard # 49.
The NSF 49 describes 4 biosafety levels, ranging from 1 for normally innocuous agents to 4 for lethal air spread agents such as the Ebola.
3 classes of cabinets are described :
– Class I cabinets supply user and environmental protection only.
– Class II cabinets provide not only user and environmental protection but also sterile conditions in the work space.
– Class III cabinets are gas tight enclosures accessible through hermetic gloves only, kept at a constant negative pressure of 120 Pa at least, and equiped with either a double exhaust HEPA filtration system or HEPA + incineration system.
The NSF 49 refers to class II biological safety cabinetry only.
Class II cabinets are classified into two types :
– Type A cabinets provide an average inflow velocity at the work surface opening of at least 0.38 m/s and may release the HEPA filter exhausted air into the laboratory.
– Type B cabinets provide an average inflow velocity at the work surface opening of at least 0.5 m/s, the exhausted HEPA filtered air is rejected outside of the laboratory through a duct and positive pressure contaminated plenums (if existing) must be surrounded by negative pressure enveloppes.
3 kinds of type B cabinets are defined according to the percentage of air recirculated within the cabinet : a minor part in B1 cabinets, not at all in B2 (also called “total exhaust”), most of it in B3 cabinets.
Israflow manufactures class I and all types of class II cabinets.