6 major differences between North American and European BSC design standards
NSF/ANSI Standard 49 and EN 12469
NSF49 Standard and EN12469 are both standards by which Biological Safety Cabinets (BSCs) are manufactured which, more importantly, govern how they perform. ANSI (American National Standards Institute) recognized NSF49 in 2002, though the standard has been in use since the 1970’s. NSF49 was also the basis from which the EN12469 standard was derived.
NSF49 (NSF) standardizes and recognizes the different subcategories of Class II BSCs (A1, A2, B1, B2) while EN12469 (EN) defines a “general Class II cabinet." The EN cabinet is nearly equivalent of the NSF Class II type A2 BSC.
Of note are the differences between the NSF and EN standards; these differences are discussed below.
Microbiological Challenge Testing for protection: EN12469 adopted this section of NSF49 identically for both testing and acceptance.
Downflow Velocity: EN places a requirement on downflow; NSF does not. However, NSF requires a larger test sample size and requires traceable test equipment for more verifiable testing results. This means testing performed per NSF is more reliable and precise/accurate.
Inflow Velocity: NSF is very specific about inflow requirements (which are used to distinguish between subcategories of the Class II BSC). Using a direct inflow measurement (DIM) as the primary standard provides repeatable and accurate inflow measurements. EN performs inflow tests by measuring the airflow above the exhaust HEPA filter and back calculating the inflow. EN’s methodology allows for calculation errors and any multiple sets of test data can provide different velocity values. (NSF A2 requires 0.5 m/s, EN requires 0.4 m/s).
Performance Envelope: Defined as the air speed parameters for which the cabinet must operate, NSF requires that the Class II cabinet must function +/-0.025 m/s of the inflow and downflow set points. EN does not have a matching specification.
Pressurization Testing: NSF requires that every unit manufactured undergo a “Soap bubble pressure leak test” to verify the cabinet is of airtight construction. EN only requires a “type-test” performed by an independent laboratory.
Construction: NSF emphasizes cleanability of contaminated surfaces.
Regardless of the differences between the NSF49 and EN12469 standards, the Biological Safety Cabinet is only as safe as the individual operating it. Operation, maintenance and certification protocols/schedules should be adhered to as prescribed by the cabinet’s manufacturer and their standards.