Integrity Testing of Freeze Dryer Inlet Filters -PHSS Technical Monograph No.8 (Revised 2008)

This Monograph provides an overview of the integrity testing requirements for freeze dryer inlet filters. The tests covered include the Diffusive Flow Test and the Water Based Test.
Other methods such as aerosol challenge testing have not been included, as generally their sensitivity and calibration reliability, coupled with the necessary contamination of the filter with oil particles, does not make them a suitable candidate for this application.
In-situ testing (performing the test without removing the filter or housing from the plant) is now achievable and expected by the regulatory authorities, and is therefore concentrated on in this monograph. However, with the exception of pipework modifications, the areas examined would also be relevant to performing the tests remotely.