VentilFlex® RKV

VentilFlex RKV - Our products - Kompozitor

VentilFlex® RKV

Flexible composite liner of high heat-resistance for ventilation systems

DIN EN 12237, TG 1216
Pressure class: D
Fire class: A2-s1, d0
Fire resistance class: Class EI 60



The VentilFlex® tube, still in its soft state is drawn in the ventilation tube or duct to be lined, where being inflated with steam, it takes the shape of the duct and by the effect of heat, it gets hardened irreversibly so creating a heat and corrosion-resistant, air-compact composite liner tube with the hardness of steel.

VentilFlex® is applicable for lining and building air-engineering ducts thanks to its following features:

  • it does not burn, does not conduct fire
  • does not corrode
  • perfectly air-compact
  • is of high hardness and is light-weighted
  • has variable diameter
  • has circle, square or other shape of boundary line
  • up 80 m long ventilation duct can be formed without extension
  • can be painted without primer
  • does not discharge materials harmful to health
  • The joints and eaves are made of metal.


Ventilation ducts are of exhausting and suction types.
To the suction types, stricter health-compactness requirements apply.

The results of the air-engineering qualification inspection carried out at the VTT Technical Research Centre of Finland:

VentilFlex RKV - Our products - Kompozitor   VentilFlex RKV - Our products - Kompozitor

From the compactness aspect, VentilFlex® is of category D, which (except for the E special category) is to be considered as the highest class.


VentilFlex® RKV technical parameters

Fire protection class A2 s1 d0
30 minutes of fire-retarding 1000 °C
Diameter 100 – 1200 mm
Length 3 – 80 m
Allowed deviation angle 30°
Wall thickness 4,5 mm
Density 1,9 g/cm3
Tensile strength 145 N/mm2
Corrosion-resistance 3 – 10 pH
Freeze resistance -50 °C


Environmental conformity

The VentilFlex® technology has had the recommendation of such organisations, which were established by building and mechanical engineering designers’ companies in order to facilitate the designers’ work in having the best choice of appropriate materials. They include the Swedish and Byggvarubedömningen organisations.
The guarantee we provide for the technology with VentilFlex® ventilation ducts installed by our trained professional partners is 25 years.

Places of application

VentilFlex® chimney liner tubes are mainly used for lining the ducts of existing buildings. The technology is fairly simple. The flat lining tube folded into half along the length is drawn in the ducts, and then it is inflated with air and hardened with steam. The liner takes the trace of the duct it is drawn into even if it is not straight. The shape of its cross section and the dimensions may be amended without having any joints in place. The installation of the liner can always be completed in a few hours without any deconstruction at all.

In Scandinavia, first of all, in Sweden, some one and a half million metres of ventilation ducts have been equipped with VentilFlex® liners to date.

VentilFlex RKV - Our products - Kompozitor

Ventilation ducts lined with VentilFlex®


Further details: