Recommendation
Airflow velocity measurements should be taken at locations where meaningful
and reproducible results can be obtained. This typically at a distance of 15-30
cm from the filter face.
Rationale for Recommendation
The primary reason for airflow velocity measurements in unidirectional
airflow areas (e.g, area where products , product contact packaging components,
and product contact surfaces are exposed) is to ensure adequate airflow to
protect the materials from external airborne contamination and to verify
continued compliance with qualified conditions. The adequacy of the environment can be determined, in part, from airflow velocity and air flow pattern studies,
and from particulate matter monitoring (at the working position).
Accurate measurements can be taken ad changes over the detected when air
flow velocity are evaluated at a predetermined distance from filter surface,
which is sufficiently close to the filter surface to be reproducible to detect
changes in the performance of the filter.
The airflow velocity depends on the design of the filling line, room
design, and air-handling system. Once velocity is determined, it is important to
ensure that the velocity stays within the specific parameters. Routine air
velocity measurements should be taken at the same locations used during the initial airflow studies to ensure consistency.
