Monday, 4 March 2019

Airflow Velocities and Cleanrooms: How fast, how slow, and where to measure?

Air is of fundamental importance to cleanrooms, either as a contamination source (microorganisms carried in the air-stream) or as a control measure to minimize contamination (through the supply of clean air and controlling the direction of air movement). Therefore, controlling a cleanroom requires careful attention to the factors of air filtration, air velocity and air flow. While cleanrooms are typically designed to achieve turbulent airflow, with clean air devices, and EU / WHO GMP Grade A / ISO 14644 class 5 areas, the air is designed to be unidirectional whereby the air direction and air velocity are designed to remove any contamination deposited into the air-stream away from the critical area. These devices contain HEPA filters, which control the air-speed and direction.

In relation to this topic, Tim Sandle has written a new article:

Poor airflow uniformity leads to turbulent airflow and vortex formation. In terms of the velocity of the air, this is described in some regulatory documents: 0,.45 meters per second within arrange of 20%. Whether achieving good airflow (and thereby avoiding poor airflow) needs to conform to the range specified in regulatory guidance documents has been a long-standing issue, particularly given the non-scientific origins of the regulatory guidance values. This article considers regulatory guidance on airflow velocities and the way that these are verified, and whether satisfactory airflow can be achieved outside of these guidance values. The discussion extends to consideration of the verification of these parameters at working height, especially in light of if this the most appropriate location by which to measure air velocities.

The reference is:

Sandle, T. (2018) Airflow Velocities and Cleanrooms: How fast, how slow, and where to measure?, Journal of GXP Compliance, 22 (6): 1-10

See IVT -

Posted by Dr. Tim Sandle, Pharmaceutical Microbiology

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