Compressed air is a critical cGMP utility — and it is the most under-engineered system on the plant. From compressor sizing to ISO 8573 quality classes, here is the design playbook that works.
1. Capacity Sizing Done Right
- List every air-consuming user with FAD requirement
- Apply a diversity factor (typically 0.7–0.8)
- Add 20% buffer for future expansion
- Size to 110% of peak demand at design pressure
2. Oil-Free vs Oil-Lubricated
For pharma cGMP, oil-free screw compressors are the standard for product-contact applications. Oil-lubricated may be used for utility-grade air with appropriate filtration — but require careful risk assessment.
3. Air Quality per ISO 8573
- Solid particles: Class 1 or 2
- Moisture: Class 2 (pressure dewpoint -40°C)
- Oil: Class 1 or 2 (≤ 0.1 mg/m³)
4. Redundancy & Reliability
N+1 configuration. Auto-changeover. Buffer-tank sizing for 5–10 minutes of demand. Dual desiccant dryers with regeneration alternation.
5. Distribution Network
- Loop topology, not branch — for even pressure distribution
- Stainless steel piping for product-contact applications
- Slope of 1–2% with condensate drains at low points
- Isolation valves at every user point
6. Monitoring & Validation
Continuous pressure, dewpoint, and oil-content monitoring. Periodic ISO 8573 sampling. Documented IQ/OQ/PQ with re-qualification on major changes.
Conclusion
A well-designed compressed air system runs invisibly for decades. A badly designed one becomes the chronic complaint of every plant manager.
At H&G, we design, audit, and validate compressed air systems across pharma sectors. Contact us for capacity assessment or system redesign.