Unidirectional
airflow devices and microbiological safety cabinets are a common feature in
many laboratories, including applications to achieve contamination control.
Such devices are suitable for a variety of applications and especially where a
demarcated clean air environment is required for processing smaller items and
for practicing aseptic technique.
Unidirectional
airflow, as defined by the World Health Organization, is a rectified airflow
over the entire cross-sectional area of a clean zone with a steady velocity and
approximately parallel streamlines. Conventional unidirectional airflow
systems, where an ISO 14644 class 5/ WHO and EU GMP Grade A condition is
required, have a guidance airflow velocity of 0.36 to 0.54 m/s. This form of
airflow contrasts to turbulent flow, which is air distribution that is
introduced into the controlled space and then mixes with room air by means of
induction.
In
relation to this, Tim Sandle has written a new paper:
Sandle,
T. (2019) Risk Considerations For The Use Of Unidirectional Airflow Devices In
Microbiology Laboratories, Journal of
Validation Technology, 25 (4): 1-10 at: http://www.ivtnetwork.com/article/risk-considerations-use-unidirectional-airflow-devices-microbiology-laboratories
This
paper assesses the most common risks affecting these laboratory devices. Prior
to examining the devices and undertaking a model assessment, the paper
discusses risk assessment in general, and looks at a generalized approach for
conducting qualitative Failure Modes and Effects Analysis.
Posted by Dr. Tim Sandle, Pharmaceutical Microbiology
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