Cleanrooms (ISO 14644): Design, Function, and Classification
What Is a Cleanroom?
A cleanroom—also known as a controlled environment—is a specialized space engineered to control airborne particle concentration, including dust, microorganisms, aerosols, and chemical vapors.
In addition, temperature, humidity, and pressure differentials are precisely regulated to match each application’s requirements.
Clean air conditions are achieved through HEPA (High Efficiency Particulate Air) filtration, which performs multiple air changes per hour to maintain purity.
As a result, a cleanroom can be up to 50,000 times cleaner than a standard environment, providing optimal conditions for sterile manufacturing and precision production.
Cleanrooms are essential for sectors where air contamination can compromise quality, safety, or performance.
Why Are Cleanrooms Needed?
Industries such as pharmaceuticals, biotechnology, electronics, optics, automotive, and aerospace rely on cleanrooms to maintain strict environmental control.
In these fields, even a single particle can compromise product quality or end-user safety.
A well-designed cleanroom enables companies to:
- Prevent particle and microbiological contamination
- Maintain consistent production conditions
- Comply with national and international regulations
- Improve process reproducibility and traceability
- Reduce product failure risks and ensure safety
For example, in the pharmaceutical industry, cleanrooms ensure sterile manufacturing and packaging of medications.
In electronics and microtechnology, they protect sensitive components such as sensors and microchips from airborne contamination.
How Does a Cleanroom Work?
The operation of a cleanroom is based on continuous air filtration and controlled airflow.
Outside or recirculated air passes through HEPA or ULPA filters, which remove 99.99% of particles sized 0.3 microns or larger.
Once filtered, the air is evenly distributed through laminar flow panels or diffusers, maintaining positive pressure inside the cleanroom.
This airflow prevents contaminated air from entering or circulating back into the workspace.
The extracted air is recirculated and filtered again, keeping the environment consistently clean while optimizing energy efficiency.
In short:
- Air intake: Multi-stage filtration (pre-filters, HEPA, or ULPA filters)
- Air distribution: Controlled laminar or turbulent flow
- Positive pressure: Prevents entry of contaminated air
- Air recirculation: Continuous cleaning for stability and purity
This system ensures a stable, contamination-free environment, essential for sensitive processes such as pharmaceutical production, device assembly, or semiconductor manufacturing.
Cleanroom Standards and ISO Classification
Cleanrooms are classified by the maximum allowable number of airborne particles per cubic meter, as defined by ISO 14644-1, the international cleanroom standard.
ISO 14644-1 Classification
The ISO system includes classes from ISO 1 (ultra-clean) to ISO 9 (standard clean environment).
Each class specifies the maximum number and size of particles allowed.
For example:
- ISO 5: Common in critical pharmaceutical and semiconductor applications
- ISO 7–8: Typical for laboratories, packaging, or assembly areas
In practice:
- ISO 1–5 rooms use near-laminar airflow with multiple air changes per second
- ISO 6–9 rooms use turbulent flow with air changes measured per hour
At Star Filters, we design and build cleanrooms ranging from ISO 4 to ISO 9, meeting each client’s specific process and industry requirements.
Additional Standards
Beyond ISO 14644, several complementary regulations apply to cleanroom design and operation:
- GMP (Good Manufacturing Practices): Defines air cleanliness grades (A–D) for pharmaceutical production.
- NOM-059-SSA1-2015: Mexican standard for pharmaceutical manufacturing.
- NOM-241-SSA1-2021: Regulation for medical device manufacturing.
- NOM-249-SSA1-2010: Standards for food and cosmetic production.
- Federal Standard 209E: U.S. cleanroom standard, predecessor to ISO 14644.
Compliance with these standards ensures that each cleanroom maintains controlled, reproducible, and safe environmental conditions for critical processes.
Conclusion
A cleanroom is far more than a sealed room with filters— It is an integrated environmental control system that protects products, processes, and personnel from contamination.
Proper design, construction, and validation are essential to meet regulatory compliance, optimize energy use, and ensure consistent results.
At Star Filters, we combine engineering expertise, high-efficiency filtration systems, and certified validation procedures to deliver turnkey cleanroom solutions that meet the most demanding international standards.
We provide controlled, certified environments where air quality defines product quality.