COMMUNICATION CABLE HAVING WATER BLOCKING PROVISIONS IN CORE

摘要

COMMUNICATION CABLE HAVING WATER BLOCKING PROVISIONS IN CORE A communications cable comprising a core of transmission media such as optical fibers, for example, disposed in a core tube and a sheath system (32)includes provisions for preventing the movement of water within the cable core. Water blocking provisions (26) are disposed in the core tube and may comprise a tape or a yarn, for example, or both. The tape may comprise substrate tapes between which is disposed a superabsorbent material in powder form which upon contact with water swells and inhibits the further movement of the water. In another embodiment, a water swellable yarn may extend longitudinally linearly with the optical fibers in the core. The water blocking provisions and the ratio of the sum of the cross sectional areas of the optical fibers and of the water blocking provisions and of any other cable element within the core to the area within the core tube are such that the transmission media in the core are decoupled substantially from the sheath system in at least one direction transverse of the longitudinal axis of the cable. On the other hand, the transmission medium is coupled sufficiently to thesheath system in the longitudinal direction to cause the transmission medium substantially to be moved with the sheath system when pulling forces are applied to the cable.