Requirements for Compressed Air Used in Fermentation

I. Core Cleanliness Requirements

The fermentation process is highly sensitive to the cleanliness of compressed air. The gas must be free of oil, moisture, particulates, and microorganisms; otherwise, it may contaminate the culture medium, inhibit microbial growth, or lead to contamination incidents. Compliance with ISO 8573‑1 is typically required. Class 1.1.1 (Solid particles ≤ 0.1 μm, oil content< 0.01 mg/ m³, dew point ≤− 70℃) or higher standards.

II. Critical Control Points for Sterility Assurance

• Pre-filtration: Multi-stage pretreatment (coarse filtration, coalescence, adsorption) removes oil mist and liquid water.
• Deep drying: Employing either freeze drying or adsorption drying to ensure the pressure dew point is below − 40℃;
• Terminal sterilization: Equipped with a 0.01 μm absolute filter, achieving a microbial retention rate ≥ 99.9999%;
• System validation: Microbial challenge tests and integrity tests are conducted regularly to ensure filtration efficacy.

III. Special Considerations in Biopharmaceuticals

When used in cell culture, monoclonal antibody production, and other applications, compressed air must comply with the requirements for process gases as specified in the GMP Annex on Biological Products. Piping materials shall be 316L stainless steel, with an internal surface roughness Ra ≤ 0.4 μm; System design must eliminate dead zones and condensate accumulation, and support sterilization in place (SIP) or steam sterilization validation.