This procedure describes how to install a Corning Cable Systems 6-fiber ("6 f") Buffer Tube Fan- Out (BTF) on 2.5 mm buffer tubes or a 12-fiber ( 12-f ) BTF on 3.0 mm buffer tubes and use an outdoor applications kit (part number FAN-ODXX-YY) to pot TFE tube in BTF housings for outdoor applications. These kits are rated for temperatures from -60 to +70°C.
Fan-Outs branch the fibers from a buffer tube into individual fibers protected by 900 micron TFE protective tubing (Figure 1). The fibers can then be connectorized according to hardware interface requirements.
Outdoor application BTF kits resemble the indoor application kits. For instructions for indoor applications, refer to SRP-000-084, Indoor Applications Kit – 6- or 12-Fiber Buffer Tube Fan-Out (BTF) Assembly.
The BTF outdoor applications kit contains a two-part epoxy and a syringe which are used to fill the funnel section of the bottom part of a BTF assembly.
2. Carton Contents
Each Corning Cable Systems indoor BTF kit contains the following (Figure 2):
- BTF top
- BTF bottom
- One 6-fiber or 12-fiber 900 micron color coded assembly, 25, 36, or 47 inches long
3. Tools and Materials
The following tools and materials are required for this procedure:
- Lint free tissues
- Electrical tape
- Clean rags
- Permanent marking pen
- Wire markers
- Buffer tube stripper
- Strapping tape
- Fiber-Clean® cleaning wipes (if filling compound is present in the buffer tubes)
4. Cable Preparation
A BTF kit can be assembled any time after the cable sheath has been removed and the buffer tubes cleaned.
Installation factors such as the length of cable slack available, the location of the terminating hardware, and the question of storing buffer tube slack as opposed to cable slack, can dictate when and where you choose to mount the cable end and assemble the BTF.
Determine the total strip length requirement for your installation. This length will be:
• the buffer tube length(s) required to route the tubes from the cable sheath attachment point to the planned location of the BTF body.
• either 35 inches (for the 25-inch fiber assembly), 46 inches (for the 36-inch fiber assembly), or 57 inches (for the 47-inch assembly).
• (optional) any additional length called for in the cable stripping procedure as a safety factor.
• (optional) the distance from the cable mounting point to a work surface if you are performing an Option 2 installation.
Mark this strip length from the end of the cable with a wrap of tape.
Strip the cable in accordance with the cable manufacturer’s sheath removal instructions. Determine the cable central member and strength member yarn lengths needed to secure the cable from the instructions provided with the hardware (e.g., a LANscape® CCH, WCH, etc.).
If you are working with a grease or gel-filled water-blocked cable, use a Fiber-Clean wipe to remove any flooding compound from the buffer tubes.
Depending on the kit being used, measure 35, 46, or 57 inches of buffer tube from the end of the tubes. Mark each tube with the permanent marker at this location.
To minimize the chance of breaking a fiber, perform the remaining steps in this procedure one buffer tube at a time.
5. Buffer Tube Preparation
Secure the cable end down to a work surface with tape so that the marks on the buffer tubes can reach the work surface edge (see Figure 5).
Select the first buffer tube. Remove the buffer tube back to the mark made in the previous section with a buffer stripping tool as described in SRP-005-005, Corning Cable Systems Stripping Tool for Buffers.
Tape down the buffer tube to receive the BTF so that 1 to 2 inches of tube overhang the work surface edge (Figure 5).
If the buffer tube is Gel-free:
Carefully cut out any water block yarns with scissors (Figure 6) and skip to Step 6. Use extreme care not to cut away any fibers.
If the buffer tube is non-Gel-free:
Use a clean lint-free tissue to thoroughly dry each fiber. Then run a dry finger along each fiber to check for any filing compound residue. If residue is present on the fiber, repeat the cleaning process with a clean lint-free tissue until no residue remains.
Make sure that the fibers are clean and dry. Any residue left on the fiber will obstruct threading operations into the 900 micron assembly pieces.
Do not deform or crush the buffer tube in the next step – doing so may cause bending in the fibers.
Place the crimp tabs of the bottom piece of a BTF on the end of the buffer tube. Use pliers to gently bend the crimps tabs over the end of the buffer tube (Figure 8). Check the crimp for effectiveness by gently pulling on and twisting the tube — the tube should not move.
6. Threading the Fibers
Approximately 2 inches (5 cm) off to either side of the tube and BTF bottom, use strapping tape to secure the plastic section of the 900 micron assembly to the table’s edge as shown in Figure 9.
The plastic section of the 900 micron assembly has numbers on its plastic housing. The number 1, or blue tube, should be on the right front corner of the assembly (see the inset of Figure 9).
Separate and untangle the number 1 (blue) fiber back to the point it exits the buffer tube.
Carefully thread about three inches of the first fiber into the #1 (blue) 900 micron tube (Figure 9).
Repeat Steps 2 and 3 for the remaining fibers in sequential fiber order (i.e., orange, green, brown, etc.).
Work the threading process across the 900 micron tube assembly in the proper order. Do not let any of the fibers cross each other during this threading operation.
After all of the fibers have been inserted into the 900 micron tubes, gently push the fibers into the tubes as a group until the fiber ends protrude from the ends of the tubes.
Carefully pull the fibers out of the tube ends to take up most of the excess length between the BTF body and the 900 micron assembly.
Leave a small fiber loop between the BTF body and the 900 micron assembly to prevent fiber breakage during later steps in this procedure(Figure 10).
Untape the 900 micron assembly from the table edge. Carefully slide the assembly while gently pulling the bare fibers protruding from the 900 micron tube ends until the assembly is above the fan-out body (Figure 11).
At times the fibers will twist as a group when sliding the 900 micron assembly towards the buffer tube. Rotate the 900 micron assembly opposite the direction of twist until the fibers straighten out.
Severe twists left in the fibers could exhibit long term microbending effects on the fiber performance and add loss.
Because buffer tubes are semi-rigid, they require careful handling to compensate for the tubes memory and springy nature.
Buffer tubes will tend to quickly return to their original position after handling. Whenever you use tape to anchor the tubes down, use care to control the tubes when removing the tape.
Carefully remove the tape securing the buffer tube and reposition the BTF body on the work surface. Retape the tube to hold the body in place.
Lower the insert section into the BTF body and press it into place (Figure 12)).
Remove the epoxy envelope from its foil packet. Fill the funnel section of the BTF bottom part with epoxy supplied in the outdoor applications kit as follows (Figure 13):
- Remove the divider between the two parts of the epoxy within the envelope.
- Thoroughly mix the epoxy by pulling the envelope repeatedly over the edge of the work surface or similar object.
- Cut off one corner of the envelope. Pour at least 0.5 cc of epoxy into the syring.
- Fill the funnel section of the BTF bottom to overflowing. Do not leave any voids among the bifers in the funnel transition area (Figure 14).
- Properly dispose of the unused epoxy and syringe.
Align the top of the BTF body with the bottom and hand press them together until the top snaps into place (Figure 15).
Remove the tape from the buffer tube.
Separate another buffer tube and assemble the next BTF by repeating the steps in this section. Corning Cable Systems recommends working with the tubes in sequential order to maintain installation organization.
7. Marking the BTF
To aid in the identification and maintenance of the fan-out assemblies, use numbered wire markers to individually identify each BTF with respect to its buffer tube number if the tubes are not easily distinguished (Figure 16).
8. Fiber Termination
Trim the excess fiber lengths to a length of 2 inches (5 cm) from the end of the 900 micron tubing.
Terminate each fiber, working one BTF assembly at a time, following the instructions provided with the connectors.
Test the connectors in accordance with standard test procedures or any recommended test procedures supplied by the connector vendor.
9. BTF Installation into Hardware
The BTF can be either bolted or taped into pieces of hardware. Refer to the instructions provided with the hardware being used to determine the best method. To route the BTF assembly into the hardware:
Hold the BTF body while grasping the buffer tube just outside the assembly.
Carefully guide the BTF assembly into place, taking care to prevent the buffer tube from kinking at the entrance to the BTF body.