Fiber-Line Polyester SWELLCOAT™ yarns are low denier continuous filament fibers manufactured using a patented process and designed to water-block the smallest of voids within a cable. Of key importance is the ability of SWELLCOAT™ yarns to water-block optical fiber buffer tubes.
Buffer tubes
Buffer tubes are continuously extruded thermoplastic tubes with inside diameters generally less than 2 millimeters. The tubes typically house up to 12 optical fibers and historically have been water-blocked with petroleum filling gels and greases. Replacing filling grease with dry superabsorbent polymers (SAP) is well documented and proven to reduce both material and cable installation costs. Fiber-Line SWELLCOAT™ yarns are generally the most economical cost-per-meter-cable option and require simple low cost equipment to deploy into cables and buffer tubes.
How are SWELLCOAT™ Yarns Made?
- Fiber-Line SWELLCOAT™ yarns start with a high tenacity (8 gpd) continuous filament polyester fiber.
A low shrink fiber (HAS < 4%) is standard; however SWELLCOAT™ can be applied to any filament
fiber
- Several polyester fibers substrate denier options (150, 250, or 500 denier) are available for
optimizing customer requirements on size and strength.
- The polyester fibers are impregnated with a proprietary coating composed of Superabsorbent
Polymer (SAP) particles stabilized in a polymer resin matrix and manufactured using a patented
method. The amount of coating (10-75%wt finished yarn) can also be adjusted to meet specific
absorption requirements
- The SWELLCOAT™ patented coating process is environmentally safe and does not release solvents
into the atmosphere. All SWELLCOAT™ components are REACH compliant
- The SAP particles are spherical in shape with an average particle size of 65 micron to minimize
stress points when placed adjacent to optical fibers inside buffer tubes
- For attenuation sensitive optical fiber applications, an optional spherical SAP with an average
particle size of 30 micron is available in SWELLCOAT™ “F” yarns
- SWELLCOAT™ water-blocking yarns are available in extremely long lengths (up to 200 km) and
metered packages if necessary. Customer specific put-ups are available
Key Properties of SWELLCOAT™ Yarns
- Economical High Performance Water Blocking
- Quick Absorption Rate and High Absorption Capacity—up to 100x mass
- Spherical SAP particles stabilized in a flexible resin matrix minimize optical fiber attenuation
- High Tenacity Low-Shrink continuous filament polyester fiber substrate
- Durable, Flexible, Strong, and Snag Resistant
- Low profile compact threads ideal for small spaces
- Precision wound bobbins with multiple size and metered length options
- Simple, clean & efficient processing
- Environmentally compliant process and materials
Advantages of SWELLCOAT™ Yarns
- Direct Application of SAP
- Introducing SAP powder directly into cables appears to be most economical and efficient,
however high costs are necessary for specialized equipment such as fluidized beds and
electrostatic generators. Precautionary engineering is also needed to prevent dust explosions
Other issues include:
- Ventilation and remediation of hazardous respirable SAP dust
- Housecleaning and maintenance due to dust contamination
SAP particles are free to migrate inside cable creating non-uniform distribution which may compromise protection from water. SWELLCOAT™ yarns require minimal equipment to deploy into cable, minimal dust shielding and ventilation, and will not generate respirable dust under normal cable processing. The cable process is simplified and line requires less maintenance. No SAP migration to worry about since yarn coating holds SAP in place.
Staple SAP Yarns
Staple yarns composed of short SAP fibers are also expensive and have weak tensile properties. These yarns have a soft fluffy profile lending to large diameter which is easily compressible. The staple fibers often contain a helical wrap or core of polyester filament to improve tensile strength. These yarns may result in undesirable coupling effects to optical fibers inside buffer tubes.
The short staple SAP fibers may become air borne respirable hazards during cable processing.
SWELLCOAT™ yarns are stronger, more durable and snag resistant. They are smaller compact profile yarns taking up much less volume. This lends the yarns to fit into smaller spaces without compression, and easier deployment in between optical fibers without negative coupling effects to the buffer tube. SWELLCOAT™ yarns are also available in much longer lengths per bobbin, and bobbin weight density is much higher so space requirements are less.
Information
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