What is a Biosafety Cabinet

Biosafety Cabinets in a Microbiology Lab

Biosafety Cabinets, sometimes referred to as BSCs, provide an enclosed, ventilated work area in a lab environment to protect personnel from aerosolized pathogenic microorganisms. Biological safety cabinets can look similar to other large pieces of lab equipment, such as laminar hoods or fume hoods; however, a BSC focuses on protecting the person rather than the sample.

Here we’ll cover what defines a biosafety cabinet, its functions, and what to watch for.

What is a Biosafety Cabinet used for?

To protect laboratory personnel, a biosafety cabinet minimizes aerosol formation. It does this by ventilating air out of the hood and away from the user. Depending on the BSC class, aerosol containment can vary.

Cabinets use HEPA filtration as the first line of defense as air is drawn out of the cabinet. Also, depending on the class of biosafety hood, the filtered air may reenter the room or be vented outside through ductwork. Biosafety hoods can range from a single-user unit a few feet wide to an entire wall installation.

Biosafety Cabinet VS Fume Hood vs Laminar Flow Hood VS Clean Bench

They look similar, so it can be easy to confuse these large pieces of lab equipment, but each has a distinct purpose and operation. Knowing the level of protection you need and what type you need is critical when deciding whether to add one to a lab.

Can a biosafety cabinet be used as a fume hood?

A fume hood is built to protect the user, but instead of from microorganisms, as with a Biosafety cabinet, it is configured for toxic, odorous, and/or volatile chemicals, otherwise known as fumes. A fume hood’s airflow also differs as the air moves away from the user either vertically or horizontally, before being treated in some way either a building’s exhaust system or by filters before being cycled back into the room.

Biosafety cabinets, on the other hand, operate with a downward, vertical, unidirectional airflow that sucks air through an intake grille, preventing particulates from entering the lab environment. They also have more stringent performance criteria they must meet for inflow and downflow velocities, as well as exhaust and cross-contamination protections.

Alternatively, a Laminar flow hood isn’t designed to protect a user; it’s built to protect the items being worked on. Air is forced downward and can move towards the researcher. Return air is also untreated so it’s best used in cases without hazardous materials.  Other similar equipment includes a PCR hood, a clean bench, a dead air box, or a tissue culture hood. Each has a similar shape and is made to be a protected area, but each does very different things.

Biosafety Cabinets and Their Types: Just how many types of biosafety cabinets are there?

Biological safety cabinets have distinct classes and levels of protection, starting with Class I cabinets.

A Class I Biosafety cabinet is designed solely for operator protection. These BSCs are rather limited in their applications, as they don’t protect the sample. They feature a similar airflow pattern to a fume hood, with the addition of HEPA filtration at the exhaust outlet. Class I cabinets can be either ductless or ducted and are built for use with Biosafety containment levels 1,2 or 3.

A Class II biosafety cabinet protects both the operator and the work, making it ideal for microbiological work and pharmacy compounding.  A Class II biosafety cabinet has an open front, with inward airflow and downward-filtered air for product protection, and HEPA-filtered exhaust air. Class II biosafety cabinets are further broken down into types: A1, A2, B1, B2, and C1, each with requirements for inflow velocity through a sash opening, negative-pressure plenums, and exhaust procedures.

Class III biosafety cabinets are characterized by total containment and are fully enclosed and leak-tight. These boxes maintain a negative pressure with ventilation through double HEPA filters or could involve incineration. Class III boxes also feature attached rubber gloves for manipulating items inside the box, earning them the moniker, “glove box.” Glove boxes are built for work requiring Biosafety containment levels 1 through 4.

How To Choose A Biosafety Cabinet

Choosing your ideal biosafety cabinet depends on the job at hand, so you’ll need to know how it will be used and, more importantly, what the biosafety level is of the agents you’re working with. Once you define the biosafety level (1-4), you can select your BSC.

Other factors to consider include sash opening so you can access your working area while still maintaining safe containment, and energy efficiency. While it may be attractive to choose something kinder to power consumption, keep in mind how that affects inflow velocity, the sash height needed to maintain containment, and whether it impacts the thrust needed to compensate for filter saturation.

Biological Safety Cabinet Manufacturers

In the BSC field, some companies’ equipment stands out for safety, added features, performance, and reliability. Here are a few Biological Safety Cabinet brands we’ve carried over the years that have proven to be worthwhile investments.

Thermo Scientific has a robust line of class II systems, their 1300 series remains a popular choice with UV disinfection, and unique airflow design, these ergonomic BSCs are also energy efficient and come in a variety of sizes.

Similarly, Labconoco’s lineup focuses on ergonomics across its Class I and Class II offerings. Their popular Purifier Logic Plus line recirculates 70% of the HEPA-filtered air, passing 30% through the exhaust HEPA for excellent security. They offer all three types.

Nuair Biosafety cabinets feature the Labguard line and are an ideal solution for meeting Sterile Hazardous Drug compounding compliance or USP 800. They feature ultra-high-efficiency motors and even airflow distribution. Most importantly, their flexible plenum design is built to overcome a saturated filter, maintaining safety and reducing the number of filter changes needed throughout the year.

Esco offers models in all three classes, compatible with both HEPA and ultra-low particulate (ULPA) filters. ULPA filters trap 99.9995% of particulates down to 0.12um in diameter, vs a HEPA’s 99.97% at 0.3 um. Both are excellent; UPLA has a slight edge, as trapping smaller particles is critical in a cleanroom.

Other sterling manufacturers include Airclean and Baker, each with their take on features and benefits, and all are reliable choices.

Final Thoughts

A biosafety cabinet provides a secure, contained work area for cell culturing and life science research. They can not only protect users but also the work environment and, depending on the cabinet, the work itself. Key factors to consider when purchasing a cabinet are the level of containment needed for your studies and the size that best suits your needs. Remember, these benches need certification every year, or if you’ve rearranged your lab, to ensure you can rely on the protection.

Through the years we’ve carried many brands of biological safety cabinets, flow hoods, safety enclosures, and the like. We have had models ranging in both sizes, ducting needs, and levels of automation. Each time an instrument comes through our doors, it undergoes a rigorous inspection, a decontamination routine, and filter replacement as needed. We also provide any documentation we have on the piece so you know what you’re purchasing in advance. Contact us today about our lineup of gently used Biosafety Cabinets!