intrusion and Migration
One way of isolating the Optical Fiber from External Forces is to Place an Excess Fiber Length within on Oversized “Buffer” Tube.
Siecor/ Optical Cable fills these tubes with a Jollylike Compound to Provide Additional Cushioning and Prevent the incursion of Moisture.
NOTE : Additional Excess Length is Achieved when the “Buffered” Fibers are Stranded together during the Cabling Operation.
It is the plastic coating applied to the coating. It protects fiber from outside stress. The cable buffer is one of two types.
(I) Loose Buffer
(II) Tight Buffer
The loose buffer uses a hard plastic tube having an inside diameter several times that of the fiber. One or more fibers lie within the buffer tube. As the cable expands and shrinks with temperature changes, it does not affect the fiber as much. The fiber in the tube is slightly longer than the tube itself. Thus the cable can expand and contract without stressing the fiber. The buffer becomes the load-bearing member.
The tight buffer has a plastic directly applied over the coating. This construction provides crush and impact resistance. It is more flexible and allows tighter turn radius. It is useful for indoor applications where temperature variations are minimum and the ability to make tight turns inside walls is desired.
Strength member :
Strength members add mechanical strength to the fiber. During and after installation, the strength members handle the tensile stresses applied to the cable so that the fiber is not damaged. The most common strength members are Kevlar, Armid Yarn, Steel and Fiber glass epoxy rods.
Kevlar is most commonly used when individual fibers are placed within their own jackets. Steel and fiber glass members find use in multifiber cable. Steel offers better strength than fiberglass but in some cases it is undesirable when one wishes to maintain an all-dielectrical cables. Steel attracts lightening whereas fiberglass does not.
It provides protection from the effects of abrasion, oil, ozone, acids, alkali, solvents and so forth. The choice of jacket material depends on degree of resistance required for different influences and on cost.
The outer layers are often called the sheath. The jacket becomes the layer directly protecting fibers and the sheath refers to additional layer.
MULTIFIBER CABLE :
It often contain several loose buffer tubes, each containing one or more fibers. The use of several tubes allows identification of fiber by tube, since both tubes and fibers can be colour coded. These tubes are stranded around a central strength member of steel or fiber glass rod. The stranding provides strain relief for the fibers when the cable is bent.
Typical Mini-Bundle Cable
1 – Blue
2 – Orange
3 – Green
4 – Brown
5 – Slate
6 – White
7 – Red
8 – Black
9 – Yellow
10 – Violet
11 – Blue/ Black
12 – Orange/ Black