Biosafety cabinet downflow velocity

(.
1) The mechanical ventilation system in a Class I biological safety cabinet shall provide a minimum inward average face velocity of 75 linear feet per minute at the work opening.
What is downflow and inflow in biosafety cabinet?
Downflow and inflow characteristics ensure that no particles or microorganisms are released from the containment (personnel protection) or that products handled inside the BSC are contaminated by agents from outside (product protection) or by impurities released from other products (cross-contamination protection)._{Mar 1, 2016}.
What is the inflow velocity of a biosafety cabinet?
Class II, Type B1 biosafety cabinets must maintain a minimum average inflow velocity of 100 fpm through the sash opening and must be connected to a building exhaust system..
Both Class I and II BSC have inward face velocities (75-100 linear feet per minute) that provide comparable levels of containment to protect laboratory workers and the immediate environment from infectious aerosols generated within the cabinet.

Downflow velocity plays a critical role in product protection and maintaining an ultra low particulate environment. It can also have an effect on the noise level if set up incorrectly. A risk assessment for product entry and exit of the cabinet should always be carried out.

The downflow velocity test is used only for a class II biosafety cabinet to determine the average air descent speed and to verify the laminar flow within the work area. The downflow velocity test is specific to class II safety cabinets as it is created from direct hepa filtration to keep the air uniform.

Biosafety Cabinet Classes

Class I– provides personnel and environmental protection but not product protection.
Personnel protection is provided as a minimum velocity of 75 lfpm (0.38 m/s) of unfiltered room air is drawn through the front opening and across the work surface.
The environmental protection is provided once air is then passed through a HEPA/ULPA (High Efficiency.

Types of Class II Biosafety Cabinets

Class II biosafety cabinets can be further designated into types.
According to NSF/ANSI 49-2022: Biosafety Cabinetry: Design, Construction, Performance and Field Certification, these are: Type A1 Cabinets (formerly Type A)– maintain minimum average inflow velocity of 75 ft/min (0.38 m/s) through the work access opening, have HEPA/ULPA filtered down.

What is a Class II biosafety cabinet?

Class II biosafety cabinets are somewhere in-between—specifically, they contain partial barrier systems that rely on the movement of air to provide personnel, environmental, and product protection.
These are covered in NSF/ANSI 49-2022:

Biosafety Cabinetry – Design

Construction

Performance

And Field Certification.

What is a down flow velocity profile test?

Down flow Velocity Profile Test:

This test is performed to measure the velocity of air moving through the cabinet workspace

and is to be performed on all Class II BSCs.
Adjust the sash to its design-use position.

What is biosafety cabinetry?

Biosafety cabinetry protects personnel, products, and the surrounding environment from hazards that arise when working with pathogenic agents.
The degree of protection provided, however, is dependent on the class of biosafety cabinet (BSC) outlined in standards like NSF/ANSI 49-2022.

What is the ANSI standard for biosafety cabinetry?

The standard applies to Class II BSCs, Type A1, A2, B1, B2, and C1, which can work with agents assigned to biosafety levels 1, 2, 3, and 4.
The current edition of this standard, NSF/ANSI 49-2022:

Biosafety Cabinetry:

Design