Is there a difference between uni- directional flow and laminar flow?
Asking this question because Annex 1 to EU GMP point 3. part Grade A stated that "Laminar air flow system should provide a homogeneous air speed in a range of 0.36 - 0.54 m/s (guidance value) at the working position in open clean room aplication. The maintenance of laminarity should be demonstrated and validated. A uni-directional air flow and lower velocities may be used in closed isolators and glove boxes."
Further more is it requlatory requirements to have 0.36 - 0.54 m/s at working surface if unidirectional flow unit or (laminar flow unit?) is located in clean room and separted by curtaines or glass barrier?
Prathamesh Mane
• no, both r different concepts. unidirectional flow concept used for material movement, however laminar air flow used for specific area like dispensing, filling, micro media preparation to maintain class for area to avoid contamination as per my understanding the concept.
As the above gentlemen explained both are similar.
We need to look certain subtle differences when they are used in specific systems like Isolators. EU Annex-1 describes that in Isolator the velocity that is normally described as 0.45 m/s (+ or -20% = 0.36 - 0.54 m/s) can be operated at slightly less velocity based on its closed construction and operator design.
If you have these UDF (Unidirectional flow ) modules and or LAF’s in your clean room enclosed or placed with curtains or glasses, these systems must follow the regular guidance limit of 0.45 m/s (+ or -20% = 0.36 - 0.54 m/s). Furthermore you should monitor turbulence in all above stated designs including Isolators. Turbulence is not accepted or allowed and one must rectify immediately.