General Information

The Class II cabinet, also known as the biological safety cabinet, provides protection of personnel as well as the product.  The cabinet has an open front with inward air flow for personal protection.  Air flowing downward over the working surface is filtered by a high efficiency particulate air (HEPA) filter for product protection.   The cabinet exhaust air is also filtered through a HEPA filter. 

Cabinet Usage

The Class II Type A biological safety cabinet is used when working with infectious agents requiring Biosafety Level 2 or 3 containment.  It is not for use with volatile or toxic chemicals and radionuclides, since the cabinet exhaust is discharged into the workspace.

The Class II Type B biological safety cabinet differs from Type A in that it is hard ducted to the exhaust system and has an increased face velocity.  These features allow for work with small amounts of toxic chemicals and radionuclides in addition to infectious agents. 

Review the Recommended Procedures for the Proper Use of Biological Safety Cabinets. This section also provides a comparison of biosafety cabinet characteristics.


    The effectiveness of Class II cabinets in controlling contamination depends on:
        a.    The integrity of the filter
        b.    Filter housing
        c.    The uniformity of air flow
        d.    Proper decontamination methods


All biological safety cabinets must be certified (to be working correctly) at least once a year or whenever the equipment is relocated and newly installed.
Decontamination of a biological safety cabinet must be performed prior to moving the equipment.  It is also recommended whenever the use of the cabinet changes.

CAUTION: Formaldehyde decontamination procedures should not be attempted by research personnel.

Any questions regarding testing, certification or decontamination of Class II cabinets can be directed to the EHRS Department at X8925.

University of the Sciences in Philadelphia • 600 South Forty-third Street • Philadelphia, PA 19104-4495 • phone: 215-596-8800 • email: