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Our This vs. That series discusses the differences between two products that have similar applications. This post discusses the differences between gel buffer tubes or dry buffer tubes. First, it is important to define and discuss what buffer tubes are, and how they relate to fiber optic cables being used in 5G applications.

Buffer Tubes

Buffer tubes are used on fiber optic cables to protect the fibers from signal interference and environmental factors since they are often used in outdoor applications. Buffer tubing also blocks water, which is critical for 5G applications especially, as they are used outdoors and are often exposed to rain and snow. If water were to get into the cable and freeze, it could expand within the cable and break the fiber.

What is Gel Filled Buffer Tubes?

The gel in a fiber optic cable serves as a blockage to outdoor elements to the cable itself. The gel fills the entire part of the tube that is not occupied by the fiber itself. In addition to blocking water from getting to the fiber optic cable, the gel also provides an additional protective layer for the fiber. It also creates cohesion between the fiber and the tube.

What are Dry Buffer Tubes?

Dry buffer tubes are also used to block water from reaching the core of a fiber optic cable. This is done by using materials such as strings, tapes, and foams. These materials are often treated with a super absorbent polymer (SAP) within the tube. The material and SAP absorbs any water or other outdoor elements that may enter the tube and keeps the cable from further water infiltration. In most conditions, the SAP will dry and reactivate, which will provide long term protection to the fiber optic cable.

How Do They Compare?

Dry and gel buffer tubes have some similarities but are mostly defined by their differences. Both types of buffer tubes are used to block environmental materials from reaching the fiber in the cable. They also both act as a filler within the tube between the outer part of the cable and the core. However, the differences between the two types of buffer tubes stand out more than the similarities.

The most obvious is that one is gel insulation and one is dry. Gel insulation fills the entire tube and molds to the specific shape of the cable. Dry insulation only fills part of the tube as it wraps around the cable, and then expands to absorb anything that may get inside the cable.

A slight disadvantage to dry buffer tubes is that the SAP (super absorbent polymer) may not perform the same every time something infiltrates the tube, and it is more sensitive to saltwater than gel. A disadvantage of the gel is that it is messy when a cable is spliced and requires cleaning. For 5G applications, gel buffer tubing cannot be applied to any vertical cables since it will eventually slip down the cable.

If you're unsure about what cable or what kind of tubing you'll need in order to meet the needs of your application, consult with one of Allied’s knowledgeable sales reps by submitting an RFQ.