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Understanding the Difference Between Gel-Filled and Gel-Free ADSS Cable Technology

In response to the growing demand for dry, or gel-free, All-Dielectric Self-Supporting (ADSS) Fiber Optic Cable technology, AFL has introduced a gel-free option to its ADSS product family. With this new technology, AFL-ADSS®/Standard ADSS Fiber Optic Cable and Flex-Span® ADSS Fiber Optic Cable will now include both gel-filled and gel-free buffer tube options. To better understand this technology and how it differs from the traditional gel-filled tubes, we recently interviewed Adam Harrison, Product Line Manager.

Pictured above: AFL’s Flex-Span ADSS Cable

What is the primary difference between gel-filled and gel-free ADSS?
The primary difference between gel-free and gel-filled cables is the water blocking element. Dry cables use a water blocking binder to absorb any moisture the cable may encounter. Gel-filled cables, on the other hand, use gel to block moisture and prevent ingress. Gel-filled cables have been around for more than 30 years while gel-free cables been around for just over a decade. 
In terms of installation and maintenance, which type of buffer tube is easier to work with and more accessible? Why?
Splicing gel-free cables offers a time-saving advantage as there’s no need to clean the gel. That said, when working with buffer tubes that have more than 12 fibers in the same tube, the gel acts as an adhesive by keeping the fiber bundles grouped and facilitating easy separation. The value of time savings from splicing is largely dependent upon the application and the number of splice locations. For point-to-point connections, the savings will be minimal, but in applications such as distribution and FTTx, the time-savings element will be more pronounced. 
How does each type (gel-filled and gel-free buffer tubes) affect the overall performance and reliability of the cable?
Both options are successfully tested to the same performance standard for ADSS cables, IEEE 1222, a widely accepted industry standard that outlines testing requirements for ADSS cable. AFL believes in the appropriate application the reliability would be comparable as well. 
Can you provide examples of situations/applications where gel-filled buffer tubes are commonly used? What about gel-free buffer tubes?
Gel-filled ADSS cable has been used in both transmission, long span and distribution (short span) applications. Gel-free ADSS has primarily been utilized in distribution applications, which makes sense given the additional splice locations that exist in a distribution environment and the time-saving advantages associated with dry splicing. 

Can you discuss any specific challenges or limitations associated with either gel-filled or gel-free buffer tubes?
AFL has industry-leading maximum span length capabilities for our gel-filled ADSS cables. Currently, we intend to keep our long span/high tension cables as gel-filled and utilize gel-free cables on medium-to-short span applications. There is even the possibility that we will transition most of our short-span designs to a gel-free technology and increase the span length capabilities of gel-free cables if there is customer demand.
What factors influenced your decision to introduce this new technology (Dry ADSS) at this time?
We chose to incorporate gel-free buffer tubes into our ADSS family to cater to the growing demand from our customer base to offer this technology. We are seeing an increasing influence from the service provider and telecom markets in the rural FTTx space that strongly advocate for the dry technology. This move allows us to meet the needs of our customer base more effectively and positions us to capitalize on the growing market opportunities in this sector.

For more information on AFL’s ADSS Products, visit our website