Design of HEPA-filter units in order to prevent airborne contamination of autoclaves and freeze dryers when doors are open

摘要

In pharmaceutical manufacturing autoclaves and freeze dryers generally cause temperature differences relative to the ambient air when doors are open during loading and unloading. This causes flows of room air through the openings creating contamination risks. To minimise these risks, high-efficiency particulate air (HEPA) filter units are installed above the openings to provide clean air as protection. In this paper design criteria for needed air volume flows through HEPA-filters are discussed and results from a case study describing risk situations with and without airflows through a HEPA-filter are presented.