11 Installed HEPA Filter Integrity Testing The purpose of installed HEPA filter integrity testing, also called in-situ testing, is to confirm a flawless performance during normal operation. Filter integrity measurements encompass tests for installed filter leakage, such as in the media or sealant to frame, and bypass, such as in the frame, gasket, or grid system. As such, this testing differs from factory leak testing that focuses on measuring filter integrity under laboratory conditions. Both filter leakage and bypass can result in a penetration of contaminants that exceeds the expected value of downstream concentration. As these situations may seriously harm the sterility of critical parameters, and therefore the quality of medicinal products, periodic requalification of terminal HEPA filters is required. Subject to risk assessment of the cleanroom activity, this interval is typically set at six months for GMP grade A aseptic processes. The most commonly used methods for testing the integrity of installed HEPA filters are described in the ISO 14644-3 standard: Aerosol Photometer (AP) and Discrete Particle Counter (DPC). The AP method typically uses a high concentration 10-40 ug/liter of oil-based aerosol for scanning air filters for leakage. A low concentration aerosol challenge exposure is always recommended, as this testing leads to a less contaminated filtration system and therefore an optimized energy efficiency and improved HEPA filter lifetime expectancy. Dedicated Support From AAF Flanders With AAF Flanders’ patent-pending ePTFE Filtration Technology, filters can now be scan tested with the industry standard photometer at the standard aerosol concentrations set forward, as well as the low aerosol concentration DPC method. AAF Flanders engineers work with state-of-the-art test equipment and can provide a project team or supervisor on site for practical assistance. As AAF Flanders firmly believes that independency in testing is critical, its core policy is to educate staff and test agencies locally for transferring knowledge and sharing best practices. Please contact your local AAF Flanders affiliate office for more details on the in-situ testing support that AAF Flanders can provide to ensure that terminal filter performance is optimized for its purpose.
RkJQdWJsaXNoZXIy MjgzNzA=