Tube
Tube is a duct with high reflective inner surface, which transports light rays from the exterior to the interior. This part significantly influences quantity of the transported light, especially by the quality of material and the section surface. The tube can transport light to a distance of 50 m from the roof. Tube must be made from high quality material and inner finish, which lifetime must be minimum 25 years.
Tubes:
- Hard tubes
- Bends: hard, adjustable
- Tubes from flexible materials
Hard tubes
The tubes are usually made of aluminum. Internal reflective layer depending on manufacturer is self-adhesive foil or deposited silver by electroplating. It can be also formed by several layers created by chemical vapor deposition in vacuum. Such high reflective layer can reflect to 99.8% incident light of whole daylight spectrum. Diffusion of rays is less than 4% due to multiple reflections.
Bends
Directing of the tube to the desired location in the interior or avoidance of obstacles can be achieved by bend. Bend causes light loss which is multiplied by the number of bends and their inclination. The hard bend can be adjusted to the change of the tube direction in the range of 0 to 65 degrees.
Flexible tube
Flexible or so called "soft sleeve" tube is offered by some manufacturers as a cheaper alternative of light guides. Material of these tubes is metalized polyester with a spring steel wire. The maximum recommended length of these tubes is 4 m. This duct can be bent to an angle of 90 degrees without the use of elbows. The advantage of this light guide type is a easy installation and lower cost compared with high-quality hard systems.