Hello
everyone!
Today, I will continue to explain underground optical cable installation. In this article, I will explain manual pulling optical cables and air-assisted installation of optical cables.
The optical cable can be inserted into the tube in two ways. If the sections are short, manual pulling cables using a fiber messenger is usually used. Air-Assisted optical installations are used for longer sections.
When pulling the optical cables into the pipe manually, care must be taken that the bending radius never exceeds 20D (D is diameter). After installation, the bending radius of the installed optical cable must never exceed 10D.
In order to make it easier to push the cable into the pipe, in order to reduce friction, it is necessary to use lubricants. Cable manufacturers should indicate which lubricants can be used.
Air-Assisted optical installations can be blowing and jetting (figure 2.).
Round cables, smaller in diameter and weight, are used for blowing. Blowing or jetting is a method that allows the cable to float in the tube. This way there is no friction and the cable can be easily pushed. There are special machines that allow the cable to float in the pipe (compressors), they provide constant pressure and airflow. A special machine is used to insert the cable. As we can see in the next figure.
Figure 1. Air-Assisted installation
Jetting method uses a missile at the front end of the cable, and pressure pulls the missile and pulls the cable.
Figure 2. Blowing (left side) and jetting (right side)
The use of hydraulic machines achieves greater force than the use of pneumatic machines. Therefore, a blowing machine with a pneumatic drive is used for optical cables up to 15 mm in diameter, while a blowing machine with a hydraulic drive is used for blowing optical cables with a diameter of 14 to 32 mm. Important parameters when installing optical cables in a pipe using the blowing method are distance and time. Usually, the blowing speed is about 40 to 50 meters per minute, under a pressure of 10 bars. Typically, the lengths of optical sections are from 1000 to 2000 m. Blowing distance depends on the weight of the optical cable, the pressure used, and friction.
I will continue to explain this theme in the next article >> Underground optical cable installation (6).
Thank you!
