Selecting a biological safety cabinet (BSC) is a critical part of setting up or upgrading any laboratory. The first step is to perform a detailed risk assessment with a certified biosafety safety professional (CBSP) or industrial hygienist who has knowledge of the risk levels associated with specific biological materials and chemicals that may be used. A qualified biosafety professional should have training and field experience that includes methods used to control biohazards, as well as knowledge of the design, application and testing of BSCs. After determining your specific risk, the next step is to assess how those risks will be fully met by the proper class and type of biological safety cabinet to be purchased.
1. Do I need to protect personnel and the environment, or personnel, the environment and samples? Do I need special protection from hazardous vapors?
Class I BSCs offer personnel and environmental protection only. Personnel protection occurs by constant movement of air into the cabinet and away from the user. Meanwhile, the environment is protected by filtering air before it is exhausted. A Class 1 cabinet does not protect the product from contamination. As such, a Class 1 cabinet is suitable for work involving low to moderate risk agents where there is a need for containment, but not product protection.
Class II biosafety cabinets are the most commonly used types and offer protection of personnel, the material, and the environment through HEPA filtration, laminar airflow throughout the work surface, and an air barrier at the front of the cabinet by use of a vacuum. HEPA filters effectively trap airborne particulates, removing potentially infectious agents, but volatile chemicals and gases pass through unimpeded. Use of materials that generate gases or vapors require an exhaust connection to a facility exhaust system.
Class III cabinets, also known as glove boxes, provide maximum protection for the environment and its users. They are designed to handle highly infectious microbiological agents, unknown agents, and other hazardous applications. Exhausted HEPA filtered air must pass through two additional HEPA filters or a HEPA filter and air incinerator before being discharged back into the outdoor environment.
2. What are my size limits?
Examine your maximum space allotment, especially width, to ensure the cabinet can fit properly within your work space. Ensure proper clearance and consider the location of the installment (more on that later). Lastly, make sure there is sufficient room in doorways and hallways to easily move the biosafety cabinet when needed.
3. Will construction options will I need—or want—in my BSC?
There are a range of customization options available for biosafety cabinets that can be installed without disrupting the cabinet’s airflow and containment performance. The addition of an ultraviolet light is one of the most common as it adds an extra layer of protection against exposure to infectious agents and keeps experimental materials free from contaminants. Interior LED lighting—rather than traditional fluorescent lighting—is also a popular addition. LED lighting is easier on the eyes and is energy efficient. A stainless-steel viewing window edge protector allows for enhanced visibility and better sight lines for researchers when working. Lastly, many purchasers opt to install electrical sockets within the BSC.
4. Where can I safely install a BSC in my lab?
A BSC must be installed away from doors, fans, high traffic patterns, and any device that could disrupt its airflow patterns. Ideally, a BSC should be installed in a location with a minimum clearance height of at least 6 inches above and to the side. This ensures that the air re-circulated to the laboratory is not disrupted. BSCs that are not connected to an exhaust system, however, should have a clearance area of at least 12 inches from the face filter and any overhead obstructions. In a BSL-3 and 4 lab, exhausted air is directed outside the building. In this case, as long as the building's exhaust system is used, the system should have sufficient capacity to maintain the exhaust flow if changes in the static pressure within the system occur.
5. What is the "real" price?
A BSC is a long-term investment for your lab, so be sure to carefully review your budget beforehand. Like a car, don’t trust the sticker price. Instead, inquire with the manufacturer about the lifetime cost of the BSC—taking into account operating costs, canopy exhaust connection, HEPA filter life and replacement costs, service life, maintenance schedule and costs, etc.
Nowadays, BSCs with energy-saving options are incredibly popular. A “quick start mode” enables some functions of the BSC to be turned on and off more quickly, while programmable functions allow users to schedule processes, such as sterilization, for off-hours when the energy load is considerably less. Manufacturers like NuAire even offer direct current motors that lower energy costs and reduce noise pollution, but are powerful enough to extend filter life.