Glossary
Unidirectional Airflow (UDAF)
Air flowing uniformly in one direction so that particles are reproducibly swept out of the critical working zone.
Details
Unidirectional airflow is the engineering protection that pushes contamination away from exposed product and components. Inspections cite the absence of velocity and uniformity data at the actual working position, and rapid hand movements or equipment creating turbulence that was never assessed. Check the qualification protocol, air velocity measurements, airflow visualisation video, equipment layout, and operator movement.
Related sections
Related terms
Real inspection findings
Findings from regulators' inspection documents in which this term appears.
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There was no discussion of the potential effect on the hoods and unidirectional airflow from movement of the hoods during routine cleaning.
FDA · FDA Warning Letter · 2023-05-30 -
Specifically, your smoke studies demonstrated disruption in unidirectional airflow in your BSC hood 19-00133.
FDA · FDA Warning Letter · 2025-03-11 -
Regarding your firm’s failure to perform adequate smoke studies under dynamic conditions to demonstrate unidirectional airflow within the ISO (b)(4) area, we acknowledge your commitments and we have reviewed your unidirectional flow device certification report, dated January 3, 2023.
FDA · FDA Warning Letter · 2024-04-23
