4' x 10' x 1" Air Duct Board with ECOSE Technology

Knauf Insulation EI-475-SL Eclipse Air Duct Board – Technical Product Information

Knauf Insulation EI-475-SL Eclipse Air Duct Board is a rigid fiberglass duct insulation panel designed for professional HVAC system fabrication in commercial and institutional applications. Manufactured with ECOSE® Technology, this duct board provides high thermal efficiency, excellent acoustic control, and structural integrity for rectangular and Max10 air duct systems. The board is engineered with a factory-applied foil-scrim-kraft (FSK) vapor retarder on the exterior surface and a black fiberglass mat on the airstream surface, providing long-term durability, resistance to microbial growth, and ease of handling during fabrication and installation.

Technical Specifications

• Manufacturer: Knauf Insulation
• Model Number: 503921
• Product Series: Eclipse EI-475-SL
• Product Type: Fiberglass Duct Board
• Dimensions: 4 ft x 10 ft (48 in x 120 in)
• Thickness: 1 in (25 mm)
• Material Composition: Inorganic glass fibers bonded with ECOSE® Technology binder
• Exterior Facing: Foil-Scrim-Kraft (FSK) vapor retarder
• Airstream Surface: Black fiberglass mat facing
• Thermal Conductivity (k-value): 0.23 BTU·in/hr·ft²·°F at 75°F (0.033 W/m·K)
• Service Temperature Range: -40°F to 250°F (-40°C to 121°C)
• Density: Approx. 3.0 lb/ft³ (48 kg/m³)
• Stiffness Rating: EI-475 (Medium Rigidity)
• Edge Options: Factory-molded shiplap or butt edge
• Vapor Barrier Permeance: ≤ 0.02 perms (UL 181-rated FSK facing)
• Microbial Resistance: EPA-registered antimicrobial treatment on airstream surface
• Fire Hazard Classification: Flame Spread ≤ 25, Smoke Developed ≤ 50 (ASTM E84)
• Sound Absorption (NRC): 0.70–0.90 depending on configuration
• Applications: Cooling, heating, or dual-temperature duct systems
• Environmental Certification: GREENGUARD Gold Certified
• Compliance Standards: ASTM C518, ASTM C1071, ASTM E84, UL 181, NFPA 90A/B

Performance and Application Features

• Rigid fiberglass construction provides superior thermal and acoustic performance for air distribution systems.
• FSK vapor retarder ensures effective condensation control and system integrity under varying temperature conditions.
• Black fiberglass airstream surface enhances airflow and provides resistance to mold and microbial contamination.
• Factory edges available in both shiplap and butt configurations for installation flexibility and tight duct joints.
• Medium stiffness rating (EI-475) ideal for general-purpose ductwork fabrication in light commercial applications.
• Lightweight and dimensionally stable for efficient cutting, handling, and assembly on job sites.
• Complies with UL 181 mold and microbial resistance standards for HVAC system health and safety.
• ECOSE® binder technology eliminates formaldehyde and phenol, contributing to improved indoor air quality.
• Durable surface finish suitable for long-term exposure to air velocities typical in duct systems.

Professional Summary

Knauf Insulation EI-475-SL Eclipse Air Duct Board is a professional-grade duct fabrication material engineered for reliable thermal and acoustic performance in HVAC applications. Its FSK vapor retarder, treated airstream surface, and ECOSE® Technology binder deliver consistent energy efficiency, moisture protection, and microbial control. The EI-475 stiffness rating provides ideal rigidity for most commercial and light industrial air systems while ensuring ease of fabrication and installation. Designed to meet ASTM, UL, and NFPA requirements, the EI-475-SL offers contractors a durable and compliant solution for high-performance duct construction.