Constructing a cleanroom requires careful consideration of multiple factors, including its intended function, cleanliness class, materials used, airflow design, and more. These elements must be aligned to meet the needs of various industries such as pharmaceuticals, electronics, medical devices, and food processing. Below, we outline key steps and principles to guide you through building a cleanroom.
Cleanroom Planning
The first step in constructing a cleanroom is design and planning, which directly impacts its functionality and compliance.
1. Define the Cleanroom’s Purpose
- Identify the intended use, such as pharmaceutical manufacturing, semiconductor production, or biological research.
- Determine the cleanliness classification according to industry standards (e.g., ISO 14644 Class 5 to Class 8).
- Establish technical parameters including temperature, humidity, and pressure differentials to meet environmental requirements for products or experiments.
2. Cleanroom Layout
- Zoning: Divide the cleanroom into functional areas such as the clean zone, buffer area, gowning room, and material pass-throughs to ensure separation of personnel and material flow, preventing cross-contamination.
- Personnel and Material Pathways: Design dedicated entry routes for personnel and separate passages for materials to avoid mixed traffic.
- Equipment Layout: Arrange equipment based on the production process, ensuring sufficient space for operation and maintenance.
Material Selection and Construction of Cleanrooms
Choosing the right building materials is crucial to ensure the cleanliness and durability of a cleanroom.
Walls and Ceiling
- Material Selection: Common materials include color-coated steel panels and aluminum alloy sandwich panels, which feature smooth surfaces, low dust retention, and easy cleanability.
- Sealing: Joints between walls and the ceiling must be tightly sealed to prevent dust accumulation or air leakage.
- Modular Design: Wall panels and ceilings can utilize a modular structure for easy installation and disassembly.
Flooring
Cleanroom flooring must be wear-resistant, slip-resistant, anti-static, and easy to clean:
- Epoxy Flooring: Resistant to chemical corrosion, smooth, and easy to clean.
- PVC Flooring: Offers anti-static properties, making it suitable for high-cleanliness environments.
- Polyurethane Flooring: Durable and moderately flexible.
Doors and Windows
- Doors: Cleanroom doors are typically made of airtight aluminum alloy or stainless steel, often equipped with automatic closing mechanisms.
- Windows: Double-glazed vacuum windows are used to maintain sealing while allowing clear visibility into the cleanroom.
HVAC System
The air circulation and HVAC system are central to cleanroom construction, directly impacting the cleanliness class.
Air Filtration System
Cleanrooms require High-Efficiency Particulate Air (HEPA) or Ultra-Low Penetration Air (ULPA) filters. A three-stage filtration system (primary, intermediate, and high-efficiency) removes airborne particles and microorganisms.
Air Change Rates
| Cleanroom Class | ISO Class | Air Changes Per Hour (ACH) |
| Class 1 | ISO 1 | >600 |
| Class 10 | ISO 2 | 500–600 |
| Class 100 | ISO 5 | 240–600 |
| Class 10,000 | ISO 7 | 60–90 |
| Class 100,000 | ISO 8 | 10–25 |
Airflow Patterns
- Laminar Flow: Unidirectional airflow, suitable for high-cleanliness environments (e.g., ISO 5).
- Turbulent Flow: Multidirectional airflow, suitable for medium to low-cleanliness environments (e.g., ISO 7 and ISO 8).
Temperature, Humidity, and Pressure Control
- Temperature: 18–26°C (adjusted based on process requirements).
- Humidity: 40–60% RH.
- Pressure Differential: Maintain 10–15 Pa between clean and non-clean areas to prevent contaminated air backflow.
Electrical and Lighting Systems
The electrical and lighting design of a cleanroom must meet the unique requirements of a controlled environment.
Electrical System
- All wiring and cables are installed in sealed conduits to prevent dust accumulation.
- Anti-static grounding systems are provided to avoid interference with production or experiments caused by electrostatic discharge.
Lighting System
- Sealed, dust-proof LED fixtures are used to minimize dust accumulation.
- Adequate illumination is provided to meet operational needs (typically 300–500 lux).
Cleanroom Construction
Site Preparation
- Site Clearing: The construction area must be thoroughly cleaned to ensure a level surface free of debris and dust.
- Foundation Assessment: Verify that the building foundation meets the structural and equipment load requirements of the cleanroom. Reinforce if necessary.
- Environmental Control: Minimize dust, moisture, and other contaminants in the construction area to maintain cleanliness.
Wall Installation
- Framework Assembly: Construct the main framework of the cleanroom to ensure structural stability.
- Panel Installation: Install walls using materials such as color-coated sandwich panels or stainless steel plates, ensuring smooth surfaces. Seal joints between walls, floors, and ceilings with silicone to maintain airtightness.
- Openings and Fittings: Create openings for HVAC ducts, cable conduits, and lighting fixtures based on design plans, and install corresponding fittings.
Ceiling and Overhead Work
- Main Frame Installation: Secure the ceiling support structure to bear the weight of HVAC and filtration equipment.
- Ceiling Panels: Install smooth, easy-to-clean ceiling materials like sandwich panels or PVC panels.
- Equipment Openings: Reserve openings for air filters, lighting, and other devices, ensuring proper sealing.
Floor Installation
- Base Preparation: Level and dust-proof the ground. Apply moisture-proof or conductive coatings if required.
- Flooring Material: Use cleanroom-compliant flooring such as epoxy resin or anti-static PVC, ensuring wear resistance, slip resistance, and easy cleaning.
- Sealing Treatment: Seal joints between floors and walls to prevent pollutant accumulation or air leakage.
Door and Window Installation
- Doors: Install airtight aluminum alloy or stainless steel doors, preferably with automatic closing mechanisms. Ensure tight connections between door frames and walls.
- Windows: Use double-glazed vacuum windows to maintain airtightness while allowing visibility into the cleanroom.
Air Purification System Installation
- Ductwork: Lay out ducts according to design specifications, ensuring密封性和稳定性. Duct surfaces should be corrosion-resistant and dust-proof.
- Air Filters: Install primary, intermediate, and high-efficiency filters (HEPA or ULPA), ensuring airtight seals between filters and ducts.
- Supply and Return Air Systems: Install supply and return air vents, adjusting their directions to ensure smooth airflow within the cleanroom.
Electrical and Lighting System Installation
- Wiring: Route all cables through sealed conduits to prevent pollutant accumulation.
- Lighting Fixtures: Install recessed, dust-proof LED lights to provide uniform illumination without dust retention.
- Static Control: Implement electrostatic grounding systems to protect equipment and products from static discharge.
Auxiliary System Installation
- Pressure Differential Control: Install pressure monitoring devices to maintain the required pressure difference (typically 10-15 Pa) between clean and non-clean areas.
- Sealing Inspection: Conduct leak tests on all seams, openings, and interfaces to ensure no air leakage.
Cleanroom Testing
- HVAC System: Operate the HVAC system and adjust parameters such as airflow volume, air change rate, temperature, and humidity to ensure they meet design specifications.
- Air Filtration System: Test filter efficiency to verify that particulate filtration performance meets standards.
- Lighting System: Inspect the brightness and uniformity of light distribution.
- Cleanliness Testing: Use a particle counter to measure airborne particulate concentrations and confirm compliance with design cleanliness standards.
- Pressure Differential Verification: Test and ensure that the pressure difference between clean and non-clean areas remains stable within the designed range.
- Temperature and Humidity Verification: Monitor indoor temperature and humidity to ensure they meet requirements.
- Simulated Operational Validation: Replicate actual cleanroom operating conditions to verify the integrated performance of equipment and systems.
Cleanroom Commissioning
Quality Inspection
- Inspect the installation quality of walls, floors, and ceilings to ensure smooth surfaces without cracks.
- Verify sealing integrity to prevent air leakage.
Documentation Submission
- Submit complete construction records, test reports, and relevant validation documents.
- Hand over the cleanroom for operational use after passing all acceptance criteria.
Conclusion
Cleanroom construction is a complex and meticulous engineering process that requires tailored design based on specific application needs. It involves careful planning of spatial layout, material selection, and technical parameters, along with strict adherence to construction protocols. Only through scientific design and precise execution can a cleanroom operate efficiently and provide a reliable dust-free environment for production and research.
