University of Colorado Denver

There are three different classes or Biological Safety Cabinets (BSC):

• Class I
• Class II: is further separated into four types
  • A1
  • A2
  • B1
  • B2
• Class III

All BSC use at least one type of HEPA filtration. Table 2 provides a summary of particulate protection each type of BSC offers.

Class I : BSC:

Class I BSC DO NOT provide product protection, as they only have HEPA filtration on exhausted air (figure 4).  The air that is drawn over the work area is supplied from outside the cabinet and is NOT free from possible contamination.

Material Applications for Class I BSC:

• Infectious agents

Materials NOT to be used in Class I BSC:

• Chemicals or Vapors
• Radionuclides

Note: Of the three kinds of laboratory ventilation equipment discussed (FH, LFH, & BSC), Class II and Class III BSC are the only types of equipment that can offer all types of protection: Personal, Product and Environmental.

Class II; Type A1 BSC

70% of intake air is recirculated in a Class II; type A1 BSC, rendering them incapable for use with hazardous chemicals or radionuclides. A1 exhaust is positive pressure to the room.

Material Applications for Class II; Type A1 BSC:

• Only infectious agents

Materials NOT to be used in a Class II; Type A1 BSC:

• Chemical Vapors
• Radionuclides

Class II; Type A2 BSC

70% of intake air is recirculated in a Class II; type A2 BSC.  Exhausted air is negative pressure to room.

Material Applications for Class II; Type A2 BSC:

• Infectious Agents
• Minute amounts of chemical vapors and radionuclides ONLY if exhaust is hard ducted to building.

Materials NOT to be used in a Class II; Type A2 BSC:

• Chemical Vapors (unless exhaust is hard ducted)
• Radionuclides (unless exhaust is hard ducted)

Class II; Type B1 BSC:

30% of intake air is recirculated in a Class II; type B1 BSC, the cabinet must be hard ducted to building exhaust to ensure proper negative pressure air flow through the cabinet.

Material applications for Class II; Type B1 BSC

• Infectious agents
• Minute amounts of chemicals and trace amounts of radionuclides only if it is hard ducted to building exhaust

Materials NOT to be used in Class II; Type B1 BSC:

• More than minute amounts of chemicals and trace amounts of radionuclides even if cabinet is hard ducted to building exhaust.

Class II; Type B2 BSC:

Also known as a Total Exhaust Cabinet as 100% of its intake air is exhausted through a HEPA filter through negative pressure.

Material Applications for Class II; Type B2 BSC:

• Infectious agents
• Chemicals (if hard ducted)
• Radionucleides (if hard ducted)

Materials NOT to be used in Class II; Type B2 BSC:

• Chemicals and Radionucleides (only if cabinet is not hard ducted)

Class III BSC:

AMC has no Class III BSC.

*personal protection from gasses and vapors only if the BSC is exhausted to facility exhaust system (hard ducted; fig. 6)

**environmental protection only if the BSC is exhausted to treated facility exhaust system (hard ducted; fig 6), contact EH&S if you have any questions about your particular BSC's exhaust

All Biosafety Cabinets must be certified annually. HEPA filters and airflow measurements must be taken to ensure safe operating conditions. EH&S can NOT provide this service. It is up to each laboratory PI to ensure that their BSC are in compliance. Please feel free to contact our Biosafety Officer Terry Stinnett (303-724-0235) with any questions or for a list of companies that will provide this service.

To see the difference of the airflow through each BSC please view the animations in this biocabinet tutorial