What are the basics of cleanroom design?

Cleanroom design involves several key principles to maintain a controlled environment with low levels of pollutants such as dust, airborne microbes, aerosol particles, and chemical vapors. Here are the basics:

ISO Standards: Cleanrooms are classified according to the ISO 14644-1 standard, which ranges from ISO 1 (cleanest) to ISO 9. The classification is based on the number and size of particles per cubic meter.

Federal Standard 209E: Used mainly in the U.S., it ranges from Class 1 (cleanest) to Class 100,000.

2. Airflow and Filtration

Airflow Patterns:

Unidirectional (Laminar) Flow: Air flows in a single direction, usually from ceiling to floor, maintaining uniform cleanliness.

Non-unidirectional (Turbulent) Flow: Air moves in multiple directions, suitable for less stringent cleanrooms.

Filtration Systems:

HEPA Filters (High-Efficiency Particulate Air): Capture 99.97% of particles ≥0.3 micrometers.

ULPA Filters (Ultra-Low Penetration Air): Capture 99.999% of particles ≥0.12 micrometers.

3. Environmental Control

Temperature and Humidity: Maintain specific levels to prevent contamination and ensure comfort for personnel.

Pressure Differentials: Positive pressure prevents the ingress of contaminants. Negative pressure can be used in hazardous environments to prevent contaminants from escaping.

4. Materials and Surfaces

Non-porous, Smooth Surfaces: Walls, floors, and ceilings should be made of materials that are easy to clean and do not shed particles.

Seamless Construction: Minimizes areas where particles can accumulate.

5. Personnel and Equipment

Gowning Procedures: Personnel must wear appropriate cleanroom attire, including gowns, gloves, masks, and shoe covers.

Cleanroom Furniture and Equipment: Designed to minimize particle generation and accumulation.

6. Entry and Exit Protocols

Air Showers: Personnel and materials pass through air showers to remove contaminants before entering the cleanroom.

Pass Boxes: Allow materials to be passed in and out without contaminating the cleanroom environment.

7. Cleaning and Maintenance

Regular Cleaning: Cleanrooms must be regularly cleaned using appropriate techniques and materials to maintain the desired level of cleanliness.

Maintenance of Systems: HVAC systems, filters, and other critical systems must be routinely inspected and maintained.

8. Monitoring and Testing

Particle Counters: Measure the concentration of airborne particles.

Environmental Monitoring: Regular checks for temperature, humidity, and pressure levels to ensure compliance with cleanroom standards.

9. Regulatory Compliance

Adherence to standards and guidelines set by organizations such as ISO, GMP (Good Manufacturing Practice), and others relevant to the specific industry (e.g., FDA for pharmaceuticals).

These principles ensure that cleanrooms meet the stringent requirements needed for various industries, including pharmaceuticals, biotechnology, electronics, and aerospace.