CABLE STRENGTH AND SUPPORT MEMBERS

Fiber optic cables use strength members to increase the cables' strength and protect the fiber from strain. Fiber optic cables may use central support members in cable construction. The central support members generally have buffered fibers or single fiber sub-cables stranded over their surface in a structured, helical manner. The central members may support the optical fibers as cable strength members or may only serve as fillers. Strength and support members must be light and flexible. In commercial applications, the materials used for strength and support include steel wire and textile fibers (such as nylon and arimid yarn). They also include carbon fibers, glass fibers, and glass reinforced plastics. For Navy applications, only non-metallic strength and support members are allowed.

CABLE JACKET, OR SHEATH, MATERIAL

The jacket, or sheath, material provides extra environmental and mechanical protection. Jacket materials for Navy cables have the following properties:

It is difficult to produce a material compound that satisfies every requirement without being too costly. Originally, the production of fire retardant cables included the use of halogenated polymers and additives. These fire retardant cables were also highly toxic. Commercial jacket materials currently used include polyethylene, polyvinyl chloride (PVC), polyurethane, and polyester elastomers. Most commercial jacket materials are unsuitable for use in Navy applications. Researchers have developed jacket materials that are suitable for Navy use.

Q.29 List seven properties cable jackets should have.