Fiber optic Cables are constructed in two ways: Loose Tube and tight buffered. Both contain a type of strengthening member, such as aramid yarn, stainless steel wire strands, or gel-filled sleeves. Each, however, is designed for very different environments.
Loose tube cables are designed for harsh environment conditions in the outdoors. They protect the Fiber core, cladding, and Coating by enclosing everything within fairly rigid protective sleeves or tubes.
Many loose tube cables contain a water resistant Gel surrounding the fibers. The gel helps protect the fibers from moisture, making the cables ideal for high humidity environments, where water or condensation may otherwise be problematic. The gel filled tubes can expand or contract with temparature changes, as well.
Despite the benefits, gel filled loose tube cables are not the right choice IF the Cable needs to be submerged in water, or routed around multiple bends. Excess Strain may cause the fibers to emerge from the gel.
Tight buffered cables are optimal for indoor applications. Being more robust than loose-tube cables, they are best suited for moderate length LAN or WAN connections, long indoor runs, direct burial, and for underwater use.
Rather than using the gel Layer loose tube has, Tight Buffered cables have a two-layer coating. The first is plastic, and the other, waterproof acrylate. The Acrylate keeps moisture away from the cable. The Core is never exposed when bend or compressed underwater.
Tight buffered cables may be easier to install, because there is no gel to clean up and it does not require a fan out kit for Splicing or termination.