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In-Depth Analysis and Construction Guidelines for the Return Air Column System in Class 100 Cleanrooms
Created on 07.22
I. System Composition and Material Analysis
1.1 Main Frame Structure
The return air column system uses a combination of high-strength aluminum alloy profiles:
Aluminum Base Channel: As the load-bearing foundation, 6063-T6 anodized profiles are used, with a channel depth of 50mm, wall thickness of 2mm, and an anodized coating thickness ≥15μm.
Angle Aluminum Reinforcement: Special L30×30×2mm cleanroom angle aluminum with conductive oxidation treatment ensures surface resistance in the range of 10⁴-10⁶Ω.
1.2 Airflow Channel Design
The return air system adopts a symmetrical bilateral design:
Return air duct clear width: 400mm, internally lined with perforated aluminum panels (aperture Φ3mm, perforation rate 28%).
A 50mm thick fiberglass sound-absorbing layer is installed at the back, with an NRC (Noise Reduction Coefficient) ≥0.85.
The airflow guide system uses 45° inclined baffles spaced 80mm apart to ensure laminar flow transition.
1.3 Sealing Transition Components
The system employs a triple-sealing guarantee:
Aluminum Alloy Inside Corner Column: R30mm arc transition design with pre-installed EPDM sealing strips.
Aluminum Alloy Outside Corner Column: 88° convex angle design with integrated anti-dust guide slopes.
Sealant System: Two-component silicone sealant with post-curing elongation ≥300%.
II. Key Construction Processes
2.1 High-Precision Positioning Construction
Surveying and Layout:
Uses 0.5" grade total station for 3D coordinate positioning.
Implements a "three-level verification" system, with final positioning error ≤0.5mm/m.
Seismic Leveling System:
Base isolation pads use natural rubber products (hardness 60±5 Shore A).
Leveling bolts are equipped with anti-loosening washers to ensure long-term stability.
2.2 Composite Sealing Construction
Multi-Layer Sealing System:
First layer: EPDM sealing strips with 30±2% pre-compression.
Second layer: Polyurethane foam filler with 250% expansion rate.
Third layer: Final silicone sealant application.
Special Node Treatment:
Inside and outside corner joints use dedicated transition connectors.
Wall penetration nodes are equipped with stainless steel sleeves (δ=1.2mm).
III. Quality Control Points
3.1 Material Acceptance Standards
Component | Inspection Item | Qualification Standard |
Aluminum Profiles | Surface Roughness | Ra≤0.8μm |
Sealant | Curing Time | Surface dry ≤30min |
Perforated Panels | Aperture Tolerance | ±0.05mm |
3.2 Construction Process Control
Cleanliness Control:
Core work area particle count ≤3520pc/m³.
Tools and materials must undergo alcohol wiping and ionized air dust removal.
Dimensional Control:
Verticality deviation ≤1mm/2m.
Joint misalignment ≤0.2mm.
IV. Maintenance Specifications
Routine Maintenance:
Weekly inspection of sealing strip conditions.
Monthly cleaning of return air filters.
Periodic Testing:
Quarterly air tightness testing.
Annual structural vibration testing.
This return air column system design fully considers the special requirements of cleanrooms. Through precise component assembly and strict construction controls, the system ensures long-term stable operation. It is recommended to create process mock-ups before construction and strictly adhere to clean construction standards.
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