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1. What size innerduct do I need?
2. What about the number of HDPE conduit innerducts in a casing pipe?
3. What advantage does ribbed innerduct have?
4. Can a pull tape be installed in the innerduct at the factory?
5. Can the innerduct be supplied in coils without a reel?
6. Can Innerduct be ordered with more than one length or color per reel?
7. How does the pull line get installed in the innerduct?
8. Why can I not order Plenum or Riser with inexpensive PP rope installed?
9. Why can't we get 4" Schedule 40 on a reel?
10. What is the longest length that can be put on a reel?

The general rule for Outside Plant duct depends on the method of cable placement. If the cable is being pulled into place then the Inside Diameter of the innerduct should be twice the Outside Diameter of the cable. If the cable is being blown into the conduit the cable should be just slightly smaller than the primary conduit.
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This is highly dependant on the installation. The straighter and shorter the run, the more you can fill the casing pipe. The longer and more complex the casing installation is, the less fill is applicable. Generally, the recommended percentage fills are:

• 70% (max value recommended)
• 50%-short straight runs
• 30% longer and more complex runs.
• Adjust values as needed per experience.

ASTM F2160 conduit and innerduct typically has a standard minimum cell classification of 334420C (except the slow crack growth is >96 hrs.) The specification does allow for higher numbers.
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The longitudinal ribs reduce surface area and therefore reduce friction. Ribbed innerduct is still basically a smoothwall product with the major cause of friction being the reel memory of the plastic (or helical set) which causes spiraling of the duct when pulled through a conduit system. Reducing the surface area does little to reduce pulling friction. When blowing cables into conduit the smoother the interior of the conduit the better it is for blowing the cable through it.
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Yes. Most manufacturers can install a wide range of pull tape, from inexpensive polypropylene rope (PP Rope) to expensive Kevlar pull tapes that are pre-lubricated and measured and marked. Depending on your project we can suggest the pull line that is best for your application. See the PPI Specification Flow Chart for the various pull tapes available.
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Yes. This type of packaging is usually for quantities of less than 1,000 feet per coil. Coils are generally taped at multiple points to keep them together and palletized for shipping.
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Yes. Most manufacturers provide special packaging called paralleling or segmenting. Innerduct that is parallel packaged can have two or three different lengths and/or colors per reel.
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The innerduct is extruded over the pull line. The extruder has an opening in the back side of the extrusion die that forms the HDPE tube. The pull line is inserted into this opening at the same rate as the HDPE tube is extruded providing a continuous pull line inside the innerduct.
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Underwriters Laboratories requires that any product being installed in a Plenum or Riser area of a building meet all testing requirements, including not installing Risers with preinstalled pull tape. UL is concerned that the PP rope which burns easily and smokes a great deal may not be removed and thereby increase the risk of a dangerous fire/smoke condition if a fire should develop.
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Theoretically, 4" schedule 40 can be put on a reel. However, it is not recommended. As the conduit is extruded, it is wound on a reel. As it is wound, the top of the pipe is in tension, while the bottom is in compression. This causes the pipe to oval. It is much more apparent in the larger diameters. ASTM F2160 acknowledges the effect and allows for it in the specification. 4" Schedule 40 is a relatively thin wall, and so it (and Schedule 40 diameters above 4") can have a tendency to buckle. That is why we 4" Schedule 40 on a reel is not recommended. Those diameters are available in stick pipe. Or heavier walls, such as SDR 13.5 can be put on reels.
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That depends on the Outside Diameter of the innerduct. The larger the innerduct the less material will fit on a reel. See the PPI manufacturer's web sites for their standard reel configurations.
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