Understanding the Differences in Design and Application: Biosafety Cabinet Class II A2 vs B2

Biosafety cabinets (BSCs) are essential components in laboratories and pharmacies, providing a safe environment for handling potentially hazardous materials. Among the various types of BSCs, Class II Type A2 and Type B2 cabinets are widely used, but they differ significantly in their design and application. In this blog, we will delve into these differences to help you understand which cabinet is most suitable for your specific needs.

Design Differences

Class II Type A2 Biosafety Cabinets

1. Airflow Pattern: The Class II Type A2 cabinets maintain a pattern of airflow that is drawn from the lab environment into the cabinet. They recirculate approximately 70% of the air through a high-efficiency particulate air (HEPA) filter back into the laboratory, while the remaining 30% is exhausted through another HEPA filter.

2. Protection Level: These cabinets are designed to provide a high level of protection for the product (like cultures or pharmaceuticals), the environment, and the user. However, they are not suitable for work with volatile or toxic chemicals as a primary risk.

3. Energy Efficiency: A2 cabinets typically consume less energy compared to B2 cabinets, primarily due to their recirculation of air.

 Class II Type B2 Biosafety Cabinets

1. Airflow Pattern: In contrast to A2 cabinets, Class II Type B2 cabinets do not recirculate air. They exhaust 100% of the air through a HEPA filter to the outside atmosphere. This design is crucial when handling volatile toxic chemicals and radionuclides as it prevents the buildup of potentially harmful concentrations within the cabinet.

2. Protection Level: B2 cabinets are specifically designed for work involving a significant amount of toxic chemicals and volatile radionuclides. They provide maximum protection for the user, the product, and the environment.

3. Energy Consumption: Due to the total exhaust feature, B2 cabinets are more energy-intensive and require more robust HVAC systems to compensate for the air exhaust from the laboratory.


Understanding the Differences in Design and Application: Biosafety Cabinet Class II A2 vs B2 Airflow Pattern

Application Differences


1. Class II Type A2: Ideal for working with microbiological research with no or minimal use of toxic chemicals. They are commonly used in microbiology, virology, and cell culture labs.

2. Class II Type B2: Necessary for laboratories where the work involves frequent use of volatile toxic chemicals or radionuclides as part of the procedure, like in some pharmaceutical quality control labs or research involving toxic substances.


1. Class II Type A2: Suitable for preparing non-sterile compounds or handling non-hazardous drugs in a pharmacy. This type is often seen in hospital pharmacies for routine pharmaceutical compounding.

2. Class II Type B2: Recommended for handling hazardous drugs, such as those used in chemotherapy. They are crucial in pharmacies where the preparation of sterile, hazardous compounds is a regular task.