Thanks to its excellent products and quality services, UNT Duct is one of the leading pu pre-insulated rectangular ductwork 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.

What is PU Pre-insulated Rectangular Ductwork?

It is a type of HVAC air distribution system where the duct wall is a composite sandwich panel. The core is made of Polyurethane (PU) rigid foam, which is sandwiched between two layers-typically an outer layer of aluminum foil (or other metal) and an inner layer of also aluminum foil. The term "pre-insulated" means the thermal insulation is an integral part of the duct panel, not added later as a wrap.

Construction & Materials

Core Material (PU Foam):

Type: Rigid polyurethane foam, usually a closed-cell structure with a density between 40–48 kg/m³.

Properties: Exceptional thermal insulator, lightweight, high compressive strength, and moisture-resistant.

Inner & Outer Facings:

Typically, both sides are aluminum foil (60-80 microns thick)

The inner layer (air contact side) is often smooth to minimize friction and resist microbial growth. The outer layer may be sturdier for mechanical protection.

Why Choose PU Pre-insulated Rectangular Ductwork

Feature	Benefit
Superior Thermal Insulation	PU foam has λ = 0.020 W/m·K, much lower than fiberglass or mineral wool. Minimal heat gain/loss.
No Thermal Bridging	No metal-to-metal contact through the wall, unlike externally wrapped metal ducts.
Leakage Airtightness	Sealed joints and continuous foil facing achieve very low leakage (class A or B per SMACNA standards).
Lightweight	Density ~1.3–2 kg/m² (for 20–30mm thickness) vs. sheet metal + lagging. Easier to handle, less structural support.
Corrosion & Moisture Resistant	Closed-cell foam does not absorb water; aluminum foil resists rust. No mold growth on surface.
Cleanliness	Smooth inner surface (low friction, dust collection resistance) suitable for cleanrooms, hospitals, food plants.
Fast Installation	No separate insulation, vapor barrier, or cladding-one-step assembly. Cuts fabrication time by ~50–70% versus traditional metal ducts.
Noise Absorption	PU foam provides some sound damping, reducing fan and air noise without needing additional acoustic lining.
Space Saving	Thinner overall wall (20–30mm typical) compared to metal duct + 50mm external insulation, saving ceiling plenum height.