This slide shows a series of tests to be carried out during qualification.

There are different tests for the turbulent and for the uni-directional air flows.

The differential pressure on filters is an indication of the clogging of the filters: with the charging of dust on the filters, the differential pressure will increase.

In order to keep the volume of air constant, the fan speed may increase, with the following consequences:

• Damage to filters, and passage of unfiltered air

• Particles and micro-organismes will be “pushed” through the filter units.

(Inspectors should check whether pressure differential manometers are installed on the AHUs. Without this means of monitoring the filters, the system could go out of control causing contamination problems.)

Airflow patterns are interesting to visualize (smoke tests), as zones without proper flushing can be easily identified.

It is also important to monitor air flow velocities for each HEPA filter according to a program of established intervals because significant reductions in velocity can increase the possibility of contamination, and changes in velocity can affect the laminarity of the airflow.

Airflow patterns should be tested for turbulence, as these can interfere with the flushing action of the air.