Testing sterile air filter integrity

Sterile air filter integrity is vital in aseptic processes and increasing regulatory demands are driving standards ever higher. Air filters in cartridge form must be mechanically and thermally stable to provide high performance over an operating lifetime that can be as long as two years. Since cartridges must withstand regular steam sterilization, wet gas flows and environments, it is important that the filter membrane is highly hydrophobic, and a cartridge design optimized for sterile air filtration and venting will provide sustained high performance with a concomitant reduction in consumable costs and energy consumption. The relevant test procedures such as the innovative water intrusion, bubble point and diffusion/pressure hold tests are reviewed.