Sterile filtration removes bacteria, yeasts and fine particles from compressed air where it contacts product or a cleanroom. In food, beverage, pharmaceutical and medical applications, a final sterile filter protects the product from airborne contamination.
Filtration stages
- Coalescing filter for oil and water
- Dry particulate filter
- Activated carbon for odour and vapour
- Sterile PTFE membrane final filter
Sterile filter selection
The final filter is typically a PTFE membrane rated at 0.01 micron or better, validated for microbial retention. It should be steam-sterilisable in place or replaced on a scheduled basis, and housed downstream of drying and prefiltration.
Integrity and replacement
Confirm filter integrity by testing after sterilisation or replacement, and keep a documented schedule. Prefiltration protects the membrane and extends service life, while point-of-use filters stop contamination from dead legs.