The internal thermoplastic polyethylene tubular film is needed at the stage of inflating and hardening. Its thickness is 120-150 μm, its melting point is 120 °C. Its task is to provide the required air-compactness, necessary for inflating the liner tube with air and steam. The tubular film then needs to be drawn out from the hardened FuranFlex® and FuranFlex® RWV tubes and is to be disposed in an appropriate waste container.
The heat, flame and corrosion resistant structural material of the FuranFlex® chimney liner is the mid composite layer. The term composite means a fibre-glass reinforced hard thermoplastic resin.
The resin developed for the FuranFlex® chimney liner is a liquid material consisting of the mixture of several components. Its characteristics may be modified with various additives. The thermosetting resin becomes slowly hardened at high temperature. The hardening process consists of three stages:
1. Liquid state
The viscosity at this stage is similar to that of honey. It becomes denser at cold, while it dilutes at warm temperature.
2. Soft, yet, not liquid, so-called "B" state
By the effect of a catalyst, the material is transferred from a fluid state to an already non-fluid state. It can be grasped by hand, can be bent and stored for a certain period of time. By the effect of heat, it slightly softens.
3. Hardened state
By the effect of heat or extended storage time, the resin irreversibly hardens. Once it has hardened, it can no longer be softened again. At this stage, it is already a solid structural material with excellent heat and corrosion resistant characteristics.
In the FuranFlex® material, fibre-glass is applied in the form of textile. The weight of the fibre-glass textile produced from thin cross and longitudinal fibre bundles is 330 g/m2. The longitudinal fibres of the fibre-glass textile take up the vertical weight of the installed FuranFlex® liner. The cross direction fibres provide the rigidity in the cross section of the chimney.
The fibre-glass textile is impregnated with fluid thermosetting resin, which fills the gaps in between the glass-fibres. After hardening, this forms the composite structure. The resin transfers the forces from one fibre to the others and protects the glass-fibres from corrosion at the same time. The hardness of composite structures is defined by the quantity, type and direction of the reinforcing fibres thinner than a hair. Every square metre of the 2 mm wall structure of the FuranFlex® chimney liner has 3.000.000 meters of elemental glass-fibre each with the diameter of 13 microns. The hardness of glass-fibre equals to that of steel, however, its weight is three-times lighter (2.4 g/cm3).
The mid composite layer, depending on the FuranFlex® type contains 3 or 4 fibre-glass textiles impregnated with thermosetting resin, which constitutes an inseparable unit after hardened.
The hardening of the FuranFlex® chimney liner consisting of resin-impregnated fibre-glass textile and internal foil is carried out by steam. The steam pressure forms the layers of tubular film and resin- impregnated glass-fibre textile to be of larger and larger diameter cross-section. In order to stop the increase at a certain diameter, an external non-flexible textile tube needs to be drawn on the external surface of the FuranFlex® liner. The black polyester textile is developed for temperatures below 500 °C, while the white textile of glass and Kevlar fibres is developed for temperatures below 1000 °C.
| Certification operating temperature | 200-350 °C |
| EU classification (ETA-12/0346) | T200 P1 W 2 OXX |
| Fire classification | B s1 d0 |
| 30 minute heat resistance | 500 °C |
| Fuel | gas / oil |
| Diameter | 60 – 1200 mm |
| Length | 3 – 80 m |
| Maximum declination angle | 30° |
| Wall thickness | 2,5 mm |
| Density | 1,7 g/cm3 |
| Tensile strength | 150 N/mm2 |
| Corrosion resistance | 3 – 12 pH |
| Cold resistance | -50 °C |
| Thermal conductivity | 0,27 W/m.K |
| Thermal expansion | 24.10-6 m/m.K |
| Health and environment | Certified for ventilation too |
FuranFlex25 Black is a Glass Fibre Reinforced Thermosetting Resin lining and is suitable different type gas fires, gas and oil heating boilers and especially high efficiency and condensing applications, ductwork, pipes and resleeving applications.
FuranFlex RWV has been specially developed to cater for Solid Fuel appliances and solid fuel open fires. FuranFlex RWV is suitable for all DFE type gas fires. FuranFlex RWV has been tested to 1000°C.
VentilFlex Green is suitable for lining and constructing air movement ducts (Ventilation and exhaust ducts)