Biological Safety Cabinets
The primary containment equipment used when
manipulating biological specimens in the laboratory is the biological safety cabinet
(BSC). A BSC provides varying levels of containment for potential aerosols created
during laboratory procedures and, when combined with standard microbiological techniques,
will ensure maximum protection for personnel and specimens. BSCs are classified based on
their construction, airflow velocity, airflow pattern, and method of exhausting
air. Some BSCs provide protection for both the employee and
specimen, while others only protect the employee. Characteristics of biological
safety cabinets are presented in the following table.
To determine the type of BSC you have, find the
manufacturers identification plate on the cabinet and read the entry in the Type
space. Most BSCs in use at EVMS are Class II, Type A. BSCs should be recertified each year to ensure the
equipment is operating properly and providing expected protection. Recertification
may also include BSC decontamination and filter change, so be sure to ask the certifier
when developing the contract or agreement. The National Sanitation Foundation (NSF)
issues a list of companies that manufacture Class II Biosafety Cabinets as well as a list
of accredited Field Certifiers.
| Type |
Face
Velocity* |
Airflow
Pattern |
BSL |
Product
Protection |
| Class I** |
75 |
In front; out rear and top
through a HEPA filter |
2,3 |
No |
Class II**
Type A |
75 |
70% recirculated through a HEPA
filter; exhausted through a HEPA filter |
2,3 |
Yes |
Class II
Type B1 |
100 |
No recirculation; total exhaust
via HEPA filter through hard duct to outside |
2,3 |
Yes |
Class II
Type B3 |
100 |
Same as IIA, but plena under
negative pressure to room and exhaust air is ducted |
2,3 |
Yes |
| Class III |
NA |
Totally enclosed, gas-tight
construction with glove ports; supply air inlets HEPA filtered and exhausts through two
HEPA filters |
3,4 |
Yes |
* Linear feet per minute
** CAUTION: Do not use toxic
chemicals or radionuclides in these cabinets since they exhaust back into the room.
BSL- biosafety level
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