Cleanroom Classification (ISO 14644)
Cleanroom classification under ISO 14644-1 grades a space by the maximum airborne particles permitted per cubic metre at stated sizes — from ISO 5 (very clean) to ISO 8/9 — and everything in cleanroom HVAC design flows from the class chosen.
Why it matters on an MEPF project
The class is a measurable contract: at qualification, particle counters verify the room meets its number in the agreed occupancy state (as-built, at-rest, operational). From the class follow the HEPA filtration stages and coverage, the air-change band, airflow pattern, and the differential-pressure cascade that keeps dirty air from migrating into clean zones.
For pharma, the ISO class is only half the story — GMP frameworks (Schedule M in India; EU GMP Annex 1 for exporters) overlay grades, monitoring and documentation on top. Designing the HVAC without the qualification protocol in view is how facilities pass construction and fail validation.
How it's specified in practice
| Parameter | Typical / working position | Governing reference |
|---|---|---|
| Particle limits | Counts/m³ at stated particle sizes per class | ISO 14644-1 |
| Filtration | Terminal HEPA (grade per application) with staged pre-filtration | design per class |
| Air changes | Band rises as class tightens | design practice per class |
| Pressure cascade | Positive differentials from clean to less-clean, monitored | GMP practice (Schedule M / Annex 1 where applicable) |
Common mistakes
- Buying "a cleanroom" without fixing the class and occupancy state to be proven.
- No airlocks/pressure cascade — the class survives until the first door opens.
- Ignoring recovery-time performance after door events.
- Designing to pass qualification day, not to hold class under real gowning and traffic.
Related on this site
Frequently asked
Which class does my pharma area need?
The process and its GMP grade decide, not preference — sterile operations demand the tight classes; secondary packing far looser. The qualification protocol should be agreed before design, because it defines what "done" means.
What is the difference between ISO class and GMP grade?
ISO 14644 grades particle cleanliness; GMP grades (A/B/C/D style frameworks) add microbiological limits, monitoring and operational rules. Pharma facilities must satisfy both mappings.
Standards referenced: ISO 14644-1 · Schedule M (India, pharma) · EU GMP Annex 1 (exporters)