How does a Class II, Type A2 Biosafety Cabinet Work?

12/4/2020 Seth De Penning

The Class II, Type A2 Biosafety Cabinet (BSC) stands at the forefront of design and functionality, crucial for creating clean, controlled environments to advance scientific research. While manufacturers construct these cabinets to align with rigorous standards such as NSF/ANSI 49 and EN 12469, they are certified for compliance by independent parties who test against these standards to ensure the cabinets can be officially listed. This process guarantees that the cabinets meet the highest safety and functionality standards, making them indispensable in research and clinical settings worldwide.

Protection Offered

The design of Class II, Type A2 BSCs offers comprehensive protection:

  • Personnel Protection: Inward airflow prevents hazardous substances from escaping and reaching laboratory personnel.
  • Product Protection: HEPA-filtered laminar airflow over the work surface minimizes cross-contamination between samples.
  • Environmental Protection: Exhaust air is filtered before release, reducing hazardous substance emissions.

Airflow Dynamics and Protective Mechanisms

The effectiveness of the Type A2 BSC starts with its sophisticated airflow management. It draws room air through the front grille, creating a protective air curtain to prevent hazardous aerosols from escaping the cabinet. This inflow air acts as a barrier at speeds of at least 100 feet per minute (0.51 m/s), ensuring personnel protection against biohazards.

The cabinet channels air under the work surface and up through a rear plenum powered by an internal blower. This air is cleverly divided: approximately 70% is recirculated through a HEPA filter back into the cabinet as laminar, or unidirectional, downflow over the work area. This airflow pattern minimizes the potential for cross-contamination, providing stringent product protection necessary for sterile procedures.

A dedicated HEPA filter exhausts the remaining 30% of the contaminated air from the cabinet. This feature underscores the environmental protection these cabinets provide, ensuring no contaminants escape into the laboratory or external surroundings.

Class II, Type A2 biosafety cabinet airflow drawing

Independent Functionality and Laboratory Integration

A vital attribute of the Type A2 BSC is its capability to operate independently from a laboratory's HVAC system. It features a motor or motors that manage airflow to maintain precise and safe conditions inside the cabinet. This independence allows for more flexible laboratory design and reduces installation costs by eliminating the need for external ducting. When handling small quantities of volatile chemicals, the BSC can be optionally connected to the building's exhaust system via a canopy connection, enhancing safety by effectively removing hazardous chemical vapors from the work environment.

Global Standards

Class II, Type A2 cabinets are developed by manufacturers to align with the rigorous requirements of international safety standards, targeting certification under NSF/ANSI 49 and EN 12469. These standards are the most widely recognized benchmarks for modern-day biosafety cabinets, setting guidelines for structural integrity, airflow dynamics, and filtration efficacy critical for certifying a BSC's safety capabilities. NSF/ANSI directly manages listings and certifications for compliance with its standards, while certifications under EN 12469 are handled by third-party certifiers such as TÜV Nord. Achieving these certifications is a testament to a product's compliance and reliability across global laboratories.

Applications in Diverse Laboratory Settings

These cabinets are indispensable across diverse settings, including pharmaceutical development, clinical research, microbiology laboratories, and pharmacy drug compounding. They are essential for applications involving pathogens or sterile materials, where rigorous control of cross-contamination is crucial. Class II, Type A2 BSCs in tissue culture labs provide an aseptic environment for manipulating sensitive samples that protect cultures from environmental contaminants. Similarly, in pharmacy settings, these cabinets ensure the sterility of compounded medications, safeguarding pharmaceutical preparations from microbial contamination and environmental pollutants—critical for patient safety and product efficacy.


In conclusion, the Class II, Type A2 Biosafety Cabinet ensures laboratory safety and precision across various scientific and pharmaceutical settings. These cabinets embody the convergence of advanced engineering, stringent standards compliance, and practical functionality. Implementing Type A2 BSCs in laboratories not only underscores a commitment to maintaining sterile conditions but also enhances the reliability of results, thus contributing significantly to scientific advancements and public health safety. By effectively managing airflow to provide triple-layered protection—personnel, product, and environmental—these cabinets establish themselves as indispensable tools to handle biohazards safely. As research continues to push the boundaries of what is possible, the role of the Class II, Type A2 Biosafety Cabinet will remain pivotal in navigating the complex landscape of laboratory safety and contamination control.

Seth De Penning, NuAire Lab Equipment

About the Author

Seth De Penning

Seth David De Penning has 8 years of experience working in the laboratory equipment industry and has spoken on the topic of biosafety cabinets to academic, government, and research institutes in multiple countries around the world.