Material
&
Strength |
- PVC: vulnerable to impaction damage - Disconnection: Possibility
of dis-connection of connected points of outer duct due to ground
compressive load.
- Thermal expansion & contraction during the installation
period and in service |
- Stand good against impaction damage and no damage risk from
freezing temperature. - Strong Concavo-convex shape provides
good strength and stays same shape against ground compressive
load.
- Stays stable from thermal expansion & contraction of duct
during or after installation |
Installation |
- Many individual connections: maximum length is 6 meters. -
To construct manhole to diverse direction of the line.
- Complicated installation work as the insertion of inner ducts
is in the second stage after the installation of outer duct.
- Causes traffic troubles (jamming) in case of urban installation.
- Inner duct may twist in the course of insertion.
- Maximum number of inner duct is limited to 3 ducts. |
- No duct connections in-between two manholes up to 500 meters
or more. - Single installation process: No need to go through
complicated inner duct insertion process owing to readily built-in
both outer and inner ducts.
- To by-pass minor hurdles and skips un-necessary construction
of manhole to diverse direction of line within the radiation of
curbing angle.
- Increase of duct efficiency by increase of numbers of inner
ducts to be inserted up to 5 ducts at approx. same price.
- Light weight allows easy handling and transportation. |
