Pulling or Blowing method for the optic fiber cables ?

Pulling or Blowing method for the optic fiber cables ?

♦Pulling method :
•Pulling rope pre-installed
•Equipment and manpower at two sides
•High sidewall forces on cables and ducts
•may lead to cable damage
•Mainly manual pulling is practiced.
•Machine pulling needs one hydraulic power pack
•Mainly used for straight duct route
•Suitable for short distance (few 100m) installation

♦Blowing method :
•No pulling rope to install
•Equipment and manpower at one side
•Forces on cable and duct can be monitored and
•controlled and minimal chance of cable damage
•Large compressor and/or hydraulic power
•pack at one side
•Preferred for duct route with multiple
•bends and undulations
•Preferred for long distance (over 2km) installation

♦Cable blowing is the process of installation of optical fiber cable into a pre-installed duct.
♦Compressed air is injected in the duct inlet after few hundred meters of cable is pushed into the duct.
♦Compressed air flows at high speed through the duct and along the cable. The pushing force is applied mainly near the cable inlet by a pushing device.

♦♦The most important point to be considered♦♦
♦Duct Fill Ratio (DFR)
The ratio between cable and duct size is known as ‘Duct Fill Ratio’.
There are two methods to calculate it :
a) The ratio between cross sectional area of cable and inner space of the duct.
DFR = d2/D2 x 100
Where,
d= cable diameter
D= duct inner diameter
For optimum blowing performance DFR to be kept between 35 to 65%.
b) The ratio between cable diameter and duct inner diameter.
DFR = d/D x 100
For optimum blowing performance DFR to be kept between 30 to 80%.
For conventional cable of diameter equal or larger than10 mm: 30 to 50%
For micro cable of diameter 1-9 mm: 30 to 80%
Higher DFR helps to achieve longer blowing distance particularly in straight route. Higher DFR also prevents cable buckling effect particularly for cables with low stiffness. However, high DFR may result in shorter blowing distance in the route having multiple bends.
Therefore, an optimized DFR needs to be maintained to achieve best blowing performance.

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Source: LinkedIn

Credits: Mr. Ahmed Fawzy Shaaban, CCNA, RCDD®, DCDC®