Clean Room (Requirements & Classification)

Clean rooms play a vital role in biomedical engineering and other high-tech industries where strict contamination control is essential. These specialized environments are designed to minimize airborne particles, regulate environmental conditions, and ensure product safety and reliability. In this article, we will explore their key features, requirements, and classifications.

What is a Clean Room?

A clean room is an engineered environment designed to maintain extremely low concentrations of airborne particles. It is well-isolated, strictly controlled for contamination, and regularly cleaned.

Cleanrooms are essential in fields such as biomedical engineering, semiconductor manufacturing, and scientific research. Their purpose is to protect sensitive materials and processes from dust, airborne organisms, and vaporized particles.

Key Features of a Clean Room

A clean room is characterized by:

1. Air filtration and ventilation systems that continuously supply particle-free air.
2. Construction materials that do not shed particles.
3. Processes designed to minimize particle generation.
4. Personnel protocols, including specialized garments that prevent particle emission and do not themselves produce particles.
5. Operational rules that minimize particle transmission in specific areas.

Clean Room Requirements

A clean room must maintain an environment free from pollutants and contaminants. Key requirements include:

• Standards and classification (Following international standards, such as ISO 14644-1)
• Monitoring particle concentration and airflow patterns
• Control of environmental parameters, including temperature, humidity, and pressure
• Proper room design, cleaning protocols, and staff attire

Clean Room Classification

Cleanrooms are classified according to the maximum allowable concentration of airborne particles, as defined by the ISO 14644-1 standard. The classes range from ISO Class 1 (the cleanest, with the fewest particles permitted) to ISO Class 9 (the least strict).

Each class specifies particle limits at different sizes, ensuring the appropriate level of cleanliness for various scientific and industrial applications.

Types of Contamination

The main types of contamination in clean rooms are classified as follows:

• Particle contamination: Solid particles that can disrupt airflow or contaminate materials. Sources include personnel (skin, hair, clothing fibers), materials (paper, cardboard), and mechanical actions (sawing, sanding).
• Molecular contamination: Gases or vapors, such as alcohol, paint, or glue, that are not filtered by standard particle filters.
• Surface contamination: Oils, creams, powders, and other residues that settle on surfaces.

GMP Classification

Clean rooms adhering to GMP standards classify air cleanliness into four grades: A, B, C, and D. Particle limits are specified for inactive (at rest) and active (in operation) conditions, following the U.S. Federal Standard 209E.

Achieving higher cleanliness levels (A, B, C) requires consideration of room size, layout, equipment, and personnel.

Particle Measurement

Particles, which are invisible to the naked eye, are monitored using precise instruments. Methods include:

• Particle counting
• Airflow assessment
• Culture media sampling

Clean Room Design & Airflow Types

Clean rooms can be categorized based on airflow systems:

• Conventional (non-unidirectional) airflow: Air passes through ceiling filters, mixes in the room, and exits via wall vents.
• Unidirectional (laminar) airflow: Air moves linearly, typically from ceiling or wall vents, creating a uniform flow and minimizing contamination (Used for classes 1, 10, and 100 cleanrooms).
• Low mixed or combined airflow: Air enters from walls or ceilings and exits through the floor or opposite wall, designed for specialized cleanliness needs.
• Isolated microenvironments (isolators): Small, sealed areas with direct airflow control, providing the highest level of contamination control.

Ventilation & Air Conditioning

Proper ventilation is critical. HVAC systems filter incoming air to reduce particle load. The airflow pattern must be designed to maintain cleanroom standards.

Cleanroom Equipment & Garments

The essential equipment and garments used in cleanrooms are as follows:

• Head garments: Prevent hair and skin particles from contaminating the environment.
• Cleanroom devices: Specialized cabins and fan-filter units for precision measurements and microelectronics manufacturing.
• Lighting: Yellow or red-green lighting may be used in photolithography to prevent unwanted exposure to short-wavelength light.

Conclusion

Cleanrooms enable precise work in highly controlled environments. Beyond their technical specifications, they reflect a broader commitment to safety, quality, and innovation in industries where even the smallest impurity can compromise outcomes. As technology advances, the role of cleanrooms will continue to expand, emphasizing not only the importance of strict standards but also the need for continuous improvement in design, monitoring, and operation.