The Difference Between Biosafety Cabinets and Laminar Flow Cabinet

When you walk into a research laboratory, there is a piece of equipment that is often referred to by many different names: Fume Hood, PCR Cabinet, Laminar Flow Cabinet, Biosafety Cabinet or Pass Box.   An important thing to note, however, is that not all of these “cabinets” are created equally; in fact, they have very different protective capabilities.   The common thread is that the equipment provides laminar air flow for a “clean” work area, but it is important to know that not all equipment provides additional personnel or environmental protection.

Below is a general guidance on the differences between two common pieces of lab equipment at BIOBASE that both provide laminar flow of air; biological safety cabinets (BSC) and the laminar flow “clean bench”.  Both of these pieces have high efficiency particulate air (HEPA) filters, which control airborne particulate materials by removing the most penetrating particle size of 0.3 μm with an efficiency of at least 99.99%.  The direction of the airflow out of the cabinet is very different, however, and therefore each piece of equipment is appropriate for specific types of work. 

Laminar Flow Cabinet

The laminar flow Cabinet discharges HEPA-filtered air from the back or top of the cabinet across the work surface and toward the user. These devices only provide product protection. They can be used for certain clean activities, such as the dust-free assembly of sterile equipment or electronic devices. Clean benches should never be used when handling cell culture materials, drug formulations, potentially infectious materials, or any other potentially hazardous materials. The worker will be exposed to the materials being manipulated on the clean bench potentially resulting in hypersensitivity, toxicity or infection depending on the materials being handled. Horizontal Laminar Flow Cabinet must never be used as a substitute for a biological safety cabinet.

Class II Biological Safety Cabinet

The Class II biological safety cabinet (BSC) comes in a variety of types.  All Class II BSC types provide personnel, environmental and product protection.  Airflow is drawn into the front grille of the cabinet, providing personnel protection.   The downward flow of HEPA-filtered air provides product protection by minimizing the chance of cross-contamination across the work surface of the cabinet.   Exhaust air is passed through a certified HEPA filter and is particulate-free, which provides environmental protection.  Depending on the type of Class II cabinet, exhaust air may be re-circulated to the laboratory (Types A1 and A2) or discharged from the building via a canopy or “thimble” connected to the building exhaust.   Exhaust air from Types B1 and B2 BSCs must be discharged directly to the outdoors via a hard connection.

HEPA filters are effective at trapping particulates and thus infectious agents but do not capture volatile chemicals or gases.  Only Types B1and B2 BSCs exhausting to the outside should be used when working with volatile, toxic chemicals, and amounts must be limited.