Sterile filter integrity testing proves that a compressed air final filter is intact and capable of retaining bacteria. In pharmaceutical and food applications, a documented integrity test is required before the filter is released for service.
Test methods
- Bubble point test
- Forward flow diffusion test
- Pressure hold test
- Water intrusion test for hydrophobic membranes
When to test
Test new filters before installation, after steam sterilisation, and at defined intervals in service. A failed test means the membrane is damaged, blocked or incorrectly installed, and the filter must be replaced or reseated.
Documentation
Record the test results, batch and operator for audit. Combine integrity testing with a replacement schedule and prefiltration, so the sterile membrane is not used as a general-purpose particle filter.