Blown optical fiber technology is an exciting method of delivering a fiber solution that provides unmatched flexibility and significant cost savings when compared to conventional fiber cables. In a blown optical fiber system, the fiber route is “plumbed” with small tubes.
These tubes, known as microduct, come in 5- and 8 mm diameters and are approved for riser, plenum, or outside-plant applications.They are currently available as a single microduct, or with two, four, or seven microducts bundled (straight, not twisted) and covered with an outer sheath, called multiducts.
They are lightweight and easy to handle. Splicing along the route is accomplished through simple push-pull connectors. These microducts are empty during installation, thereby eliminating the possibility of damaging the fibers during installation.
Fiber is then installed, or “blown,” into the microduct.The fiber is fed into the microduct and rides on a current of compressed air. Carried by viscous drag, the fibers are lifted into the airstream and away from the wall of the microduct, thereby eliminating friction even around tight bends.
In a relatively short period, coated fibers can be blown for distances up to 1 km (3281 ft) in a single run of 8-mm-diameter microduct, up to 1000 ft vertical, or through any network architecture or topology turning up to 300 tight corners with 90° bends of 1-in. radius for over 1000 ft, using 5-mm-diameter microduct.
The practical benefits of BOFT systems translate directly into financial benefits for the end user. For most installations, the cost of a BOFT infrastructure is similar to or slightly higher than the cost for conventional fiber cabling.
Savings can be realized during the initial installation because (1) it simplifies the cable installation by allowing the pulling of empty or unpopulated microduct; (2) fewer, if any, fiber splices may be required; and (3) you only pay up front for those fibers that you need immediately. The additional expense of hybrid cables is eliminated.
True cost savings and the convenience of blown optical fiber are realized during the first fiber upgrade or during moves, additions, and changes. An upgrade of an existing fiber backbone will generally incur workplace disruptions such as removing a ceiling grid, moving office furniture, and network downtime that requires the work to be done outside normal business hours.
New fibers can be added to a BOFT system simply by accessing an existing unpopulated microduct and blowing in the fibers. There is no disruption to the workplace, and the process requires a minimal amount of time to complete.
In the event that there are no empty microducts, the existing fiber can be blown out in minutes and replaced with the new fiber type(s) immediately. The flexibility of BOFT makes it particularly amenable to renovation and retrofit applications.