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Air changes per hour (ACPH)
Ref. Guideline: ISO 14644
Air changes in pharmaceutical cleanrooms play a significant role in maintaining the cleanroom quality as per ISO Cleanroom Classification through the HVAC system. Air change per hour is the number of total replacements of any room air in one hour. if the supply of air by the HVAC system in one hours is equal to the volume of the room then it will be one air change per hour. FDA recommends maintaining a minimum of 20 air changes per hour in cleanrooms.
Why is ACPH Required in the Pharmaceutical Industry?
1. Control of Particulate Contamination: Proper air changes help maintain cleanliness by removing particulate matter and airborne contaminants.
2. Regulatory Compliance: ISO 14644 and GMP guidelines mandate specific ACPH levels for cleanroom classifications.
3. Temperature and Humidity Control: High air changes ensure consistent environmental conditions.
4. Support for HEPA Filtration: ACPH aids HEPA filters in maintaining the required cleanliness levels.
5. Safety in Operations: Prevents accumulation of hazardous substances or microbial contaminants.
How is ACPH Selected for Cleanroom Grades?
ACPH values are determined based on the ISO 14644 classification of the cleanroom, its operations, and contamination risk levels.
Example:
✅ ISO Class 5 (Grade A):
Where Used: Sterile manufacturing (e.g., aseptic filling, capping, LAF, BSC).
ACPH Requirement: 240-480 ACPH.
Reason: To maintain extremely low particle counts (≤3,520 particles/m³ for ≥0.5 μm).
✅ ISO Class 7 (Grade C):
Where Used: Background for Grade A areas.
ACPH Requirement: 60-120 ACPH.
Reason: Supports aseptic operations while maintaining cleanliness.
✅ ISO Class 8 (Grade D):
Where Used: Secondary packaging, warehouse.
ACPH Requirement: 20-45 ACPH.
Reason: General cleanliness with reduced contamination risk.
