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Cleanroom Ductwork Design: Material Selection and Leakage Testing
Leaky ductwork is the most common hidden defect in cleanroom construction. Even a small leak at a flange joint can compromise pressurization cascade and introduce contaminants that bypass the filtration system.
Cleanroom ductwork fabrication and sealing standards are far more demanding than commercial construction. SMACNA Class A leakage testing at 125% of design pressure is standard for pharmaceutical applications, compared to Class C which is acceptable for most commercial buildings.
Casing Construction and Thermal Break Design
SMACNA Class A leakage is required for ISO 5-6 cleanrooms while Class B suffices for ISO 7-8. Testing at 125% of design pressure is standard for pharmaceutical compliance.
HEPA and ULPA Filtration Configurations
Internal duct surfaces need 2.5 micron Ra finish or better for ISO 7 and cleaner. Standing seam or welded longitudinal joints prevent particle accumulation.
Duct Material Selection by ISO Class
Stainless steel 304 is the standard for pharmaceutical cleanroom ductwork because of its corrosion resistance and smooth internal surface. Galvanized steel costs 40-60% less and works for ISO 7-8 applications in dry environments, but it can develop white rust in humid conditions.
Air Changes Per Hour Based on ISO Classification
Stainless steel 304 is preferred for pharmaceutical ductwork. Galvanized steel suits ISO 7-8 dry applications but costs 40-60% less than stainless steel.
Sensible and Latent Heat Load Calculations
Aluminum ductwork suits galvanic corrosion or weight reduction concerns. Stainless 316L with electropolished finish is required for potent compound handling areas.
Leakage Testing Standards and Acceptance Criteria
SMACNA Class A allows maximum leakage of 3.6 L/s per 100 m2 of duct surface area at test pressure. We have seen projects where poor flange sealing caused ten times that leakage rate, completely undermining the pressurization cascade design.
EC Plug Fans Energy Savings
SMACNA Class A allows maximum leakage of 3.6 L/s per 100 m2 at test pressure. Testing uses calibrated orifice plates with digital manometers accurate to within 1%.
Chilled Water Coils and Filtration Selection
Common leak points include flange connections, access door seals, and duct penetrations. Two-part epoxy sealants for static joints and EPDM gaskets for access panels are standard.
Duct Layout for Contamination Control
Chilled air ducts must be designed with continuous slope toward drain points to prevent condensation accumulation. We specify closed-cell elastomeric foam insulation with vapor barrier and minimum thickness of 50 mm for chilled air and 75 mm for chilled water below 7C.
EU GMP Annex 1 Requirements
Chilled air ducts require continuous slope toward drain points. Condensate drain pans must be stainless steel with dual-slope design to prevent water accumulation.
ISO 16890 Reclassification Standards
Access doors required at all duct-mounted devices and every 10-15 meters of straight run. Gasketed doors with cam-lock or compression latches maintain leakage ratings.
Insulation and Pre-Startup Quality Control
We always include a pre-startup cleanliness verification as a contractual milestone. Using borescope cameras to inspect internal duct surfaces before connecting to terminal HEPA filters catches debris and construction dust before cleanroom startup.
Oversizing and Humidity Control Issues
Closed-cell elastomeric foam insulation with vapor barrier of perm rating below 0.05 is standard. Minimum 50 mm for chilled air and 75 mm for chilled water below 7C.
AHU Procurement RFQ Specifications
Pre-startup cleanliness uses borescope cameras to inspect internal surfaces. No visible dust or moisture is acceptable, documented with photographic evidence.
A successful project requires thorough planning. Evaluating cleanroom ductwork design carefully ensures the best outcome for your specific requirements and budget.
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In order to serve you better, if you could kindly send an e-mail to nick@biogreenness.com for questions and details about your theoretical and special architectural plans, projects, and product specifications, your request will be responded to as soon as possible.
We'll call you
In order to serve you better, if you could kindly send an e-mail to nick@biogreenness.com for questions and details.
