Pre-insulated Phenolic Ductwork Panel

Thanks to its excellent products and quality services, UNT Duct is one of the leading pre-insulated phenolic ductwork panel manufacturers and suppliers in China. Welcome to buy the high quality and customized products from our factory. We will offer you the best service and fast delivery.

 

 

A pre-insulated phenolic duct is a three-layer composite structure, designed to combine load-bearing capacity, insulation, and protection:

 

Layer	Material	Function
Inner Layer	Aluminum foil	Forms the airtight channel for airflow; resists corrosion and air leakage.
Core Insulation	Phenolic foam	Provides thermal insulation, fire resistance, and structural support.
Outer Layer	Aluminum foil / Aluminum Sheet/ Galvanized steel	Protects the phenolic core from moisture, mechanical damage, and UV radiation.

 

Phenolic foam: The key insulation material, made by foaming phenolic resin (a polymer derived from phenol and formaldehyde). It has a closed-cell structure, which minimizes heat transfer and prevents moisture absorption.

 

 

 

 

Pre-insulated phenolic ducts stand out for their superior properties compared to traditional duct systems (e.g., galvanized steel ducts with external insulation like rock wool or glass wool):

 

1. Excellent Thermal Insulation

Low thermal conductivity: Typically 0.025 W/(m·K) at 25°C, far lower than rock wool (0.035–0.045 W/(m·K)) or glass wool (0.038–0.048 W/(m·K)). This reduces heat loss/gain during airflow, improving HVAC energy efficiency by 10–20% in some cases.

Stable insulation over time: The closed-cell structure prevents moisture absorption (unlike fibrous insulations), so its thermal performance does not degrade with humidity.

 

2. Superior Fire Safety

Phenolic foam is inherently fire-retardant (meets Class B1 or higher fire ratings in most standards, e.g., GB 8624-2012 in China, EN 13501-1 in Europe):

Self-extinguishing: Does not support combustion when the ignition source is removed.

Low smoke emission: Produces minimal toxic smoke (low levels of CO and corrosive gases) during a fire, reducing risks to human safety and equipment damage.

High charring resistance: Maintains structural integrity at high temperatures (up to 180–200°C) by forming a protective char layer, delaying duct collapse.

 

3. Lightweight & Easy Installation

Low density: Phenolic foam has a density of 30–60 kg/m³, making the duct 50–70% lighter than galvanized steel ducts with equivalent insulation. This reduces structural loads on buildings and simplifies transportation.

Modular design: Pre-fabricated in standard lengths (1–3m) and shapes (rectangular, circular, or oval) at factories. On-site installation only requires cutting, bonding, or flanging-no need for heavy tools or separate insulation work. Installation time is typically 30–50% shorter than traditional systems.

 

4. Airtightness & Moisture Resistance

Airtight: The aluminum inner layer and factory-sealed joints minimize air leakage (≤2% of design airflow, meeting SMACNA standards), reducing HVAC energy waste.

Moisture-proof: The closed-cell phenolic core and aluminum outer layer prevent condensation and water penetration, avoiding mold growth and duct degradation.

 

5. Sound Insulation

The dense, closed-cell structure of phenolic foam absorbs airflow noise and external sound, reducing duct-borne noise compared to metal ducts. This is ideal for noise-sensitive areas like hospitals, offices, and schools.