Biosafety Cabinets: Class I, II and III Biological Safety Cabinets
HEPA-filtered biological safety cabinets for clinical, hospital, research and cell therapy labs: Class I, Class II (A2 and B2) and Class III, NSF/ANSI 49 listed, with placement, exhaust and certification planning. Free quote.
Talk with a lab safety storage specialist: (801) 855-8560 · Sales@Labs-USA.com
What a Biosafety Cabinet Does
Biosafety cabinets (BSCs), also called biological safety cabinets, are the primary containment device for work with infectious agents, cell cultures, clinical specimens and other biological materials. They use HEPA-filtered airflow to protect the operator and the room, and Class II and III cabinets also protect the work product from contamination.
Unlike the storage cabinets in our laboratory safety cabinets range, a BSC is a ventilated work enclosure. Choosing one means matching the class to your biosafety level, then planning power, exhaust, placement and yearly certification.
Labs USA supplies NSF/ANSI 49 listed Class I, Class II (Type A2 and B2) and Class III cabinets from leading manufacturers for hospital microbiology, virology, molecular diagnostics, cell therapy and research labs. We coordinate placement, exhaust connections, base stands and certification scheduling.
Biosafety Cabinet Classes Compared
| Class | Protects | Airflow | Typical use |
|---|---|---|---|
| Class I | Operator and environment (not product) | Inward airflow at the front opening, HEPA-filtered exhaust | Enclosing equipment, low-risk aerosol work |
| Class II, Type A2 | Operator, product and environment | About 70% recirculated and 30% exhausted through HEPA filters; minimum 100 fpm inflow | Most BSL-2 hospital and research work: microbiology, cell culture, clinical specimens |
| Class II, Type B2 | Operator, product and environment | 100% exhausted through a hard duct, no recirculation | Biological work that also uses volatile chemicals or radionuclides |
| Class III | Maximum containment | Gas-tight glove box, HEPA supply and double-HEPA exhaust | BSL-3 and BSL-4 agents, high-hazard work |
Most labs need a Class II Type A2. It covers BSL-1, BSL-2 and many BSL-3 procedures and can usually be installed without a hard duct (a canopy connection is used when small amounts of volatile chemicals are involved).
Class III cabinets are sealed glove boxes for the highest-risk agents and are built to order. For a deeper explanation read our guide to biological safety cabinet classes, including inflow airflow rates.
Class II Types: A1, A2, B1, B2 and C1
| Class II type | Exhaust | Chemical use | Notes |
|---|---|---|---|
| A1 | Recirculates most air; room or canopy exhaust | Not for volatile chemicals | Older design, lower inflow |
| A2 | About 30% exhausted; canopy connection optional | Minute amounts with canopy exhaust | The standard choice for most labs |
| B1 | Hard-ducted; most downflow exhausted | Small amounts of volatile chemicals | Less common today |
| B2 | Hard-ducted; 100% exhausted | Volatile chemicals and radionuclides as approved | Needs dedicated exhaust fan and HVAC controls |
| C1 | Can run recirculating or exhausted | Limited, with exhaust connected | Flexible newer design |
Type B cabinets depend on the building exhaust system, so they add mechanical design and cost. We review your procedures with your biosafety officer before recommending a ducted model.
How a Biological Safety Cabinet Moves Air
A Class II biological safety cabinet works by keeping three air streams in balance. Room air is pulled in through the front grille, forming an air curtain that keeps aerosols away from the operator. HEPA-filtered air flows straight down over the work surface so the sample sits in clean air. Below the work surface, the contaminated mix is drawn back through a plenum by the cabinet blower.
In a Type A2 cabinet, roughly 70% of that air is sent back through the supply HEPA filter as downflow, and about 30% leaves through the exhaust HEPA filter on top. A HEPA filter must capture at least 99.97% of particles at 0.3 microns, the hardest size to trap.
Diagram: Esco Airstream cabinet. Green shows room inflow, blue shows filtered air and red shows unfiltered air. Some models, like this one, use ULPA filters, which are finer than HEPA.
Three ways to connect the exhaust
| Connection | How it works | Typical cabinets |
|---|---|---|
| Recirculating (non-ducted) | HEPA-filtered exhaust returns to the room | Class II Type A1, A2 or C1 for biological work without volatile chemicals |
| Canopy (thimble) | A canopy with a small air gap around the exhaust filter housing carries filtered air into the building exhaust. BMBL requires an alarm for low airflow through the canopy. | Type A1, A2 or C1 when minute amounts of volatile chemicals are used |
| Hard-ducted | The cabinet is connected directly to the exhaust duct, preferably with a dedicated fan | Type B1, Type B2 and Class III |
The exhaust connection is decided by your risk assessment, not by the cabinet catalog. It drives HVAC design and cost, so settle it before the room is laid out.
Matching the Cabinet to Your Biosafety Level
The U.S. reference is the CDC and NIH manual Biosafety in Microbiological and Biomedical Laboratories (BMBL), 6th edition. Its Appendix A ties cabinet class to biosafety level and to the protection each class gives.
| Biosafety level | When a BSC is used | Cabinet class (BMBL Appendix A) |
|---|---|---|
| BSL-1 | Work with well-characterized agents that do not cause disease in healthy adults. A BSC is not required, but it is often used to protect cultures from contamination. | Class I or Class II |
| BSL-2 | Procedures that can create infectious aerosols or splashes are done in a BSC or other physical containment. | Class II (most often Type A2); Class I where product protection is not needed |
| BSL-3 | Manipulations of infectious materials are done inside a BSC or other containment equipment. | Class II or Class III |
| BSL-4 | Highest-risk agents with no available treatment. | Class III, or Class II when used in a suit laboratory by staff wearing positive-pressure suits |
Who decides
- Your biosafety officer or institutional biosafety committee sets the biosafety level and approves the cabinet type through a risk assessment.
- Labs USA matches the class, type, width and exhaust connection to that decision and plans the room around it.
- For room features beyond the cabinet, see our BSL-2 lab design requirements guide.
Biosafety Cabinet vs. Fume Hood
This is one of the most common lab planning questions. The short answer: a biosafety cabinet protects against biological hazards; a chemical fume hood protects against chemical vapors. They are not interchangeable.
Need both biological and chemical protection? A Class II Type B2 cabinet exhausts 100% of its air, allowing limited use of volatile chemicals alongside biological work.
| Feature | Biosafety cabinet | Chemical fume hood |
|---|---|---|
| Primary protection | Biological agents (bacteria, viruses, fungi) | Chemical vapors and fumes |
| HEPA filtration | Yes, supply and exhaust | No, dilution exhaust only |
| Product protection | Yes (Class II and III), sterile downflow | No, room air sweeps the work |
| Chemical use | Limited (small amounts in A2; more in B2) | Yes, designed for chemical work |
| Hospital use | Microbiology, virology, cell therapy, pharmacy | Pathology (formalin), chemistry, toxicology |
Compare in detail in our PCR hood vs. biosafety cabinet guide and fume hoods for clinical and medical labs.
Biosafety cabinet vs. laminar flow clean bench vs. PCR workstation
All three use HEPA filters, which is why they get confused. Only the biosafety cabinet protects the person doing the work.
| Feature | Biosafety cabinet (Class II) | Laminar flow clean bench | PCR workstation |
|---|---|---|---|
| Protects the operator | Yes, inward air curtain | No, filtered air blows toward the user | No |
| Protects the sample | Yes, HEPA downflow | Yes | Yes, plus UV for DNA decontamination |
| Safe for infectious agents | Yes, at the approved biosafety level | No | No |
| Typical use | Microbiology, cell culture, clinical specimens | Sterile, non-hazardous prep such as media or electronics | Clean PCR set-up |
If a clean bench or PCR hood is all you need, see the store workstations further down this page and our PCR hood vs. biosafety cabinet guide.
Sizes, Options and Specifications
- Nominal widths: 3, 4, 5 and 6 ft (about 0.9 to 1.8 m). Four- and six-foot cabinets are the most common in hospital labs.
- Sash: vertical sliding sash is standard; hinged sashes are available on some models.
- Services: gas and vacuum valves, UV lamps, electrical outlets and IV bars.
- Base stands: fixed or adjustable height, with or without storage below.
- Controls: airflow alarms, ECM motors for lower energy use, and filter-life monitoring.
Allow clearance above the cabinet for filter service and exhaust, and check door and elevator sizes for delivery; a 6 ft cabinet on its stand is a large, heavy item. Budget ranges are in our safety cabinet cost guide.
Hospital and Research Applications
Microbiology and clinical specimen processing. Class II Type A2 cabinets are the standard in hospital microbiology for culture set-up and for processing respiratory, wound and blood culture specimens. Most hospital micro labs need two to four cabinets depending on volume.
Virology and molecular diagnostics. Nucleic acid extraction from clinical specimens is done in a BSC, with separate pre- and post-amplification areas to prevent cross-contamination.
Cell therapy and stem cell processing. Hospital cell therapy labs use Class II cabinets to process bone marrow, cord blood and CAR-T products under aseptic conditions; cleanroom-grade cabinets can be integrated with cleanroom furniture.
Pharmacy compounding. Biological safety cabinets serve as primary engineering controls for hazardous drug compounding under USP <800>, placed in negative-pressure rooms. See hospital pharmacy and compounding furniture.
Research and biotech. Cell culture, gene therapy and vector work at BSL-2, with flammable storage for ethanol and isopropanol nearby. See also hospital and clinical lab furniture and hospital microbiology lab furniture.
Planning the Room Around a Biosafety Cabinet
Where a cabinet sits affects how well it contains aerosols. Cross-drafts from doors, supply diffusers and people walking past can break the air curtain at the front opening.
Placement checklist
- Keep cabinets away from doors, high-traffic aisles and supply air diffusers.
- Leave clearance behind and above the cabinet for service and filter changes.
- Give the operator a stable, adjustable-height chair and a foot rest.
- Plan a dedicated circuit, and an exhaust connection for canopy or hard-ducted models.
- Place the autoclave, sink and handwashing within the BSL-2 room as required.
For sinks, airflow, finishes and autoclaves, read our guide to BSL-2 lab design requirements.
Certification, Testing and Decontamination
NSF/ANSI 49 calls for field certification of every biosafety cabinet at installation, at least once a year, and after any move, repair or HEPA filter change. Tests include:
- HEPA filter integrity (aerosol challenge)
- Inflow velocity
- Downflow velocity and uniformity
- Airflow smoke patterns and cabinet integrity
- Electrical safety and alarm function
Daily surface disinfection keeps the work zone clean; gaseous decontamination is needed before filter changes, moves or major repairs. Labs USA can connect you with certified field technicians for testing and decontamination.
Learn the difference between routine wiping and full fumigation in our biosafety cabinet decontamination guide.
Get a quote on biosafety cabinets
Tell us your biosafety level, the class and width you need, and how many cabinets. We will quote the right models, base stands, exhaust connections and delivery for your lab. Some common sizes are in stock at select manufacturers, subject to confirmation.
Working Safely in a Biological Safety Cabinet
A certified cabinet only protects people when it is used correctly. These practices follow BMBL Appendix A and the guidance most university biosafety offices give their labs.
Before, during and after work
- Purge first. If the cabinet was shut off, run the blower at least five minutes before starting so suspended particles are cleared (BMBL).
- Wipe down. Disinfect the work surface, side walls and inside of the sash before and after work. If you use bleach, follow with a sterile-water wipe so chlorine does not corrode the stainless steel.
- Keep grilles clear. Never block the front or rear grille with paper, wrappers or pipettors. Work at least four inches in from the front grille.
- Load only what you need. Extra supplies disrupt airflow. Keep clean items and dirty items apart and move your arms slowly in and out.
- No open flames. A burner creates turbulence in the HEPA downflow. Use an electric loop sterilizer or disposable loops instead.
- Don’t rely on UV. UV lamps must not be the only disinfection method. If installed, keep them clean, check output with a UV meter and turn them off when people are in the room.
- One person per cabinet. Cabinets are tested for a single operator; more than one requires a separate risk assessment.
| Standard or guide | What it covers |
|---|---|
| NSF/ANSI 49 | North American design, construction, performance and field-certification standard for Class II cabinets |
| CDC/NIH BMBL, Appendix A | Selection, installation and safe use of BSCs by biosafety level |
| EN 12469 | European performance standard for microbiological safety cabinets |
Choosing a Biosafety Cabinet: Buyer Checklist
Before we quote, we work through the same questions a biosafety officer will ask:
- Which agents and procedures, and at what biosafety level?
- Any volatile chemicals or radionuclides? That decides A2 recirculating, A2 canopy or ducted B2.
- How many people work at once, and which width (3, 4, 5 or 6 ft) fits the room?
- Is there building exhaust capacity for a ducted cabinet?
- Will the cabinet fit through doors, elevators and corridors on delivery day?
- What services go inside: vacuum, gas, outlets, IV bar?
- Who will certify it at installation and every year after?
Related Clean-Air Workstations in the Labs USA Store
These laminar flow and PCR workstations protect the sample, not the operator, so they are not biosafety cabinets and must not be used with infectious agents. For Class I, II or III biosafety cabinets, request a quote and we will match the model to your biosafety level.
Biosafety Cabinet FAQs
What is the difference between a biosafety cabinet and a fume hood?
What class of biosafety cabinet do I need?
How often do biosafety cabinets need to be certified?
What sizes do biosafety cabinets come in?
Does a Class II A2 biosafety cabinet need to be ducted?
What biosafety cabinet do hospital labs use?
Is a laminar flow hood the same as a biosafety cabinet?
How much does a biosafety cabinet cost?
Which biosafety level requires a biological safety cabinet?
Should I use the UV lamp in a biosafety cabinet?
How long should a biosafety cabinet run before use?
Need Biosafety Cabinets? Get a Free Quote
Class I, II and III biological safety cabinets with placement, exhaust and certification planning from Labs USA.