Thermaflex® G-KM Flexible Duct

Flexible Air Duct

Highly efficient, thermally insulated flexible duct for use in low and medium pressure heating and cooling systems. Acoustically rated, self-extinguishing CPE core easily expands over fittings. Core is permanently bonded to a coated spring steel wire helix that supports an ample blanket of fiberglass insulation over a fiberglass scrim and a tough polyethylene vapor barrier. Smooth liner, insulation, and tough vapor barrier provide even airflow and a double air seal.


  • Acoustically rated, self-extinguishing CPE core
  • Easily expands over fittings
  • Even airflow

G-KM Specs

Diameter 3-20 inches ID
Pressure Rating (WG)
Positive 6 inches (3˝-16˝ ID)
4 inches (18˝-20˝ ID)
Negative 1 inch (4˝-12˝ ID)
1/2 inch (14˝-20˝ ID)
Velocity 5000 FPM
Temp. Range -20°F – 200°F cont.
-20°F – 250°F intermittent
R-Value R-4.2, R-8.0