Buyer guide
Laminar flow hood vs clean bench vs biosafety cabinet
A laminar flow hood and a clean bench are the same kind of device: they blow HEPA-filtered air over the work to protect the product, not the operator. A biosafety cabinet (BSC) is built to protect the operator and the room: Class I and II draw air in at the front, and Class II also protects the product.
By ZY Cleanroom · Updated · Sources at the end of the page
How the devices differ
In common use, laminar flow hood and clean bench name one device. The CDC and NIH biosafety manual (BMBL, 6th edition) calls them clean benches or clean air devices, and says they are not BSCs.
| Device | Air path | Protects |
|---|---|---|
| Horizontal clean bench | HEPA air from the back, across the work, toward the user | Product only |
| Vertical clean bench | HEPA air downward; discharged into the room under the sash | Product only |
| Class I BSC | Room air in at the front, HEPA filter on exhaust; inflow at least 75 lfm (0.38 m/s) | Operator and room, not product |
| Class II, Type A1 | Inflow at least 75 lfm (0.38 m/s); HEPA downflow | Operator, room and product |
| Class II, Type A2 | Inflow at least 100 lfm (0.51 m/s); HEPA downflow | Operator, room and product |
| Class III BSC | Gas-tight cabinet with attached gloves | Maximum protection for worker and environment |
What may go inside
BMBL says clean benches should never be used with cell culture materials, drug formulations, potentially infectious materials or other potentially hazardous materials. The worker is downstream of the work and is exposed.
BMBL lists dust-free assembly of sterile equipment or electronic devices as a use for a horizontal bench. It lists hospital pharmacy intravenous preparation and nucleic acid preparation for PCR as uses for a vertical bench. If the material is hazardous or infectious, choose a BSC.
Air speed for product protection
FDA's 2004 aseptic guidance gives 0.45 m/s with ±20%. Annex 1 para 4.30 gives 0.36 to 0.54 m/s at the working position as a guidance value.
Worked example, assumed size: a filter face of 1.2 × 0.6 m is 0.72 m². At 0.36 m/s the face airflow is 0.72 × 0.36 × 3,600 = 933 m³/h. At 0.54 m/s it is 1,400 m³/h. This is a design check. Test velocity where your protocol says.
Certification and the room around it
BMBL says a BSC must be validated before use and after repair or relocation, and tested and certified at least annually. It asks for recertification after a HEPA or ULPA filter change. NSF/ANSI 49 covers Class II cabinets.
USP <797> asks that a primary engineering control meet ISO Class 5 or better in dynamic conditions, with unidirectional airflow maintained. A control used only for Category 1 preparations may stand in an unclassified segregated compounding area. In a classified ISO Class 7 room, USP <797> asks for at least 30 total HEPA-filtered air changes per hour.
Choosing in three questions
What is handled? If it is infectious, hazardous, a cell culture or a drug formulation, a clean bench is excluded by BMBL. Who needs protection? If the operator does, choose a BSC. What air quality does the work need? If only the product does, a clean bench is the listed use.
China's cleanroom construction code lists biosafety cabinet installation as its own item (clause 11.4) and an isolation coefficient test for biosafety cabinets (Appendix F.3). A Chinese project may need both on the test plan.
Put these in the data sheet
State the device class, the ISO class in operation, the material to be handled and its hazard, the inflow and downflow speeds, the filter grade, the certification standard, the service access and the alarms. Say who certifies it and when.
Who approves the room
Your regulator or biosafety officer judges the facility. The contractor builds to your data sheet and supplies test results. The owner keeps the responsibility. To have a room list reviewed, send it to ZY Cleanroom, a cleanroom design-and-build contractor with its own panel factory in Tianjin, China.
Questions
Common questions
Is a laminar flow hood the same as a biosafety cabinet?
No. A laminar flow hood or clean bench protects the product only and blows air toward the user. A BSC draws air in at the front to protect the operator.
Can I use a clean bench for cell culture?
BMBL says clean benches should never be used for cell culture materials, drug formulations or potentially infectious materials. Choose a BSC.
What inflow does a Class II cabinet need?
BMBL gives at least 75 lfm (0.38 m/s) for Type A1 and at least 100 lfm (0.51 m/s) for Type A2.
How often is a BSC certified?
BMBL says at least annually, and again after relocation, repair or a HEPA or ULPA filter change.
Related guides
- How long does it take to build a cleanroom?
- The Cleanroom Project Lifecycle
- Cleanroom cost per m²: published ranges by ISO class
- What a cleanroom costs to run: energy, filters and testing
- Turnkey cleanroom contractor
- Room list builder
Sources
- CDC and NIH, Biosafety in Microbiological and Biomedical Laboratories, 6th edition (revised June 2020), Appendix A, pages 370 to 376 and 387 to 388; checked 1 November 2026
- FDA, Guidance for Industry: Sterile Drug Products Produced by Aseptic Processing, Current Good Manufacturing Practice (September 2004, nonbinding; checked 1 November 2026)
- EudraLex Volume 4, Annex 1: Manufacture of Sterile Medicinal Products (published 25 August 2022, applied from 25 August 2023; checked 1 November 2026)
- Washington State Department of Health, Pharmacy Self-Inspection Worksheet, 2026 USP 797 Sterile Compounding Addendum, DOH 690-296 (January 2026), which reproduces USP <797> text by section; checked 1 November 2026
- GB 50591-2010, Code for Construction and Acceptance of Cleanroom (issued 15 July 2010, in force 1 February 2011; contents list, chapter 4 and Appendices E and G; checked 1 November 2026)
Project enquiry
Send what you have
A room list, a floor plan or only the floor area is enough to start. After you submit, send drawings by email or WhatsApp.
We reply by email within one working day. We can sign an NDA before you send drawings.
WhatsApp +44 7962 561184 is our UK number for export enquiries. The factory is in Tianjin, China.
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