How to Choose AL/PE Duct Facing Thickness & Structure: A Buyer's Guide

Many customers feel uncertain when customizing AL/PE composite duct facing — is 7μm aluminum foil sufficient? Should the PE layer be 20μm or 30μm? What's the real difference between two-layer and three-layer structures? These seemingly straightforward parameter choices directly impact duct insulation performance, service life, and production cost. This guide walks you through the selection logic for AL/PE duct facing based on actual usage scenarios.

1. Understanding the Roles: What Aluminum Foil Does vs. What PE Does

AL/PE duct facing consists of two core material layers:

Aluminum foil layer (AL) — serves dual functions: reflective thermal insulation and moisture barrier. Aluminum foil reflectivity reaches 92%–95%, making it the primary contributor to duct facing insulation performance. The dense foil layer also provides an extremely low water vapor transmission rate (≤0.02 g/m²·24h), effectively preventing external moisture from penetrating the insulation layer.

PE layer (polyethylene) — primarily provides heat-sealing capability and physical protection. The PE layer enables direct heat-sealed seams on the duct production line, eliminating extra adhesive steps and improving both production efficiency and seam reliability. It also shields the aluminum foil from scratches and corrosion during bending and handling.

Each layer plays an indispensable role — without aluminum foil, thermal insulation and moisture barrier fail; without PE, heat-sealing is impossible and the foil is vulnerable to damage.

2. Selecting Thickness by Application: Thicker Isn't Always Better

Scenario 1: Standard Commercial HVAC Supply Ducts

Typical conditions: indoor installation, ambient temperature -10°C to 40°C, no extreme humidity requirements.

Recommended specifications:

• Foil thickness: 7μm (standard specification, best cost-performance ratio)
• PE layer: 20μm–25μm (meets heat-sealing needs while providing adequate protection)
• Total laminate thickness: approximately 27μm–32μm
• WVTR: ≤0.05 g/m²·24h

Key reminder: 7μm foil already meets the reflective insulation requirements of most commercial HVAC ducts. Upgrading to 9μm or 12μm only increases cost with negligible insulation improvement.

Scenario 2: High-Temperature Industrial Ventilation Ducts

Typical conditions: factory exhaust, dryer equipment integration, ambient temperatures reaching 60°C–80°C, requiring high thermal stability and long-term durability.

Recommended specifications:

• Foil thickness: 9μm (industrial grade, better flex fatigue resistance)
• PE layer: 30μm–40μm (thicker PE improves heat resistance and mechanical protection)
• Total laminate thickness: approximately 39μm–49μm
• WVTR: ≤0.03 g/m²·24h
• PE material: HDPE recommended (maximum service temperature up to 80°C)

Key reminder: In high-temperature scenarios, the PE layer matters more than the foil. Standard LDPE softens and deforms above 60°C under prolonged exposure — switching to HDPE is the correct solution, rather than simply thickening the foil layer.

Scenario 3: Export-Grade Mid-to-High-End HVAC Ducts

Typical conditions: overseas markets requiring compliance with ASTM C553 or equivalent EN 13163 standards, with strict flame retardancy, moisture barrier, and environmental compliance requirements.

Recommended specifications:

• Foil thickness: 9μm–12μm (export customers generally accept thicker foil)
• PE layer: 25μm–35μm
• Total laminate thickness: approximately 34μm–47μm
• Compliance documentation: RoHS/REACH test reports required
• Flame retardancy: B1 grade with third-party certification

Key reminder: Export orders don't require the thickest foil available — overseas buyers prioritize overall laminate stability and compliance documentation over raw foil gauge. A 12μm foil + 30μm PE combination typically earns more buyer confidence than 15μm foil with a thin PE layer.

3. Two-Layer or Three-Layer? Structure Selection Depends on Operating Conditions

AL/PE dual-layer structure — the most basic duct facing configuration. Aluminum foil directly laminated to PE, suitable for standard HVAC supply and return ducts. Simple processing, lowest cost.

AL/PE/AL three-layer structure — double-sided foil facing with aluminum layers on both interior and exterior surfaces. The inner foil layer reflects thermal radiation from the insulation layer back inward; the outer foil reflects ambient heat radiation outward. Suitable for commercial HVAC systems demanding bidirectional insulation. Thermal performance improves approximately 15%–20% compared to single-sided foil configurations.

AL/woven scrim/PE three-layer structure — a woven fabric layer (typically PP or PET scrim, 40–60 g/㎡) sandwiched between foil and PE, dramatically improving mechanical strength and tear resistance. Tensile strength reaches 30 N/15mm or above. Suitable for industrial ventilation ducts subjected to positive pressure, external pulling forces, or frequent bending.

Key reminder: Don't use woven scrim reinforcement where high strength isn't needed — scrim adds 20%–30% to material cost and 10%–15% to basis weight. For standard indoor installations, dual-layer structure is sufficient.

4. Three Details Procurement Often Misses

1. Lamination Peel Strength

Peel strength between AL and PE layers should meet ≥1.5 N/15mm (industry minimum), with premium products achieving 3.0 N/15mm or above. Insufficient peel strength causes delamination and blistering at duct bending points — the primary cause of duct "bulging" failures. Always request peel strength test reports from suppliers.

2. Roll Wind Direction and Tension

The winding direction of AL/PE laminate (foil facing outward or PE facing outward) directly determines how the material loads onto duct production lines. If your production line requires the foil side facing outward on the roll, specify this clearly in your order. Excessive winding tension causes surface wrinkling, affecting finished duct appearance.

3. Width Precision

Standard widths include 1000mm, 1200mm, and 1500mm, with tolerance controlled within ±3mm. Inaccurate width leads to insufficient seam overlap or material waste. Before large-volume procurement, request a small trial roll to verify width consistency.

5. Hongcheng Technology's AL/PE Duct Facing Customization Capabilities

Hangzhou Hongcheng Technology specializes in aluminum foil composite materials and PE lamination composites. AL/PE duct facing is one of our core product lines. We offer:

• Foil thickness: 7μm, 9μm, 12μm available, with custom specifications supported
• PE layer thickness: 20μm–50μm, LDPE/HDPE selectable
• Laminate structure: AL/PE dual-layer, AL/PE/AL three-layer, AL/woven scrim/PE three-layer — all customizable
• Width: 1000mm–1550mm, ±3mm precision
• Flame retardancy: B1/B2 grade with third-party test reports
• Environmental compliance: Full RoHS/REACH documentation

Whether you're a HVAC flexible duct manufacturer or an export trading company, we provide one-on-one selection advice and custom solutions based on your specific duct structure and operating conditions. Feel free to contact us anytime for personalized consultation and custom service.

Tel/WeChat: +86 13758223270 Email: wendy@hcdxcl.com.cn