This article describes the structure of armored fiber cables and their benefits for the network owner. You can get the armored fiber optic cable products here or click on the following picture.
The Structure of an Armored Fiber Optic Cable
Armored fiber cables have extra reinforcing in the cable housing to prevent damage.
In basic armored fiber cable designs, the outer sleeve provides protection against wind, solvents, and abrasion. This outer sleeve is usually made of plastic such as polyethylene.
The next layer between the sleeve and the inner jacket is an armoring layer of materials that are difficult to cut, chew, or burn, such as steel tape and aluminum foil. This armoring material also prevent the fiber from being stretched during cable installation.
Ripcords are usually provided directly under the armoring and the inner sleeve to aid in stripping the layer for splicing the cable to connectors or terminators.
The inner jacket is a protective and flame retardant material to support the inner fiber cable bundle. The inner fiber cable bundle includes strength members, fillers and other structures to support the fibers inside.
There are usually a central strength member to support the whole fiber cable. This can be solid or stranded metallic or nonmetallic material.
The Benefit of Armored Fiber Optic Cable
There are many benefits for using armored fiber cables. The following is a list of the most important ones.
- Rodent Resistance
- Moisture and chemical protection
- Waterblocking of sheath interfaces
- Mechanical strength
- Thermal stability
- Corrosion protection
- Lightning protection
- Ability to be located accurately.
- Ability to be monitored
Armored Flame Retardant Fiber Optic Cable for Indoor/Outdoor Applications
Indoor/outdoor fiber optic cables have been pretty hot in the last several years and there are good reasons for this. For service providers, indoor/outdoor fiber cables really present big time and cost savings. This cable design can come from the outdoor environment and enter a building without the need to switch cable designs to have the flame retardance required indoors. This dual purpose cable can reduce the cost of the terminations and related labor to change cable designs.
The development of dry water blocking core technology has also helped indoor/outdoor fiber cable development. This dry core technology uses water swellable materials to block the flow of moisture in the longitudinal direction.
Armored Fiber Cable Sheath Design
Several potential jacket materials were considered for armored indoor/outdoor cables. The choice of jacket material depends on the required level of flame retardance in the final cable.
Polyvinyl Chloride (PVC) jacket
General purpose PVC jackets and insulations are widely used for indoor and outdoor applications for low voltage cable. They are designed to meet the flame test requirements for UL 1581 and IEC 332-3C type of test or the burner tests VW-1 and IEC332-1.
Halogen Free Polyolefins (HFPO)
The defense and transportation industry have driven the development of halogen free materials. Safety and serviceability are vastly improved by these halogen free materials which produce low smoke and fume.
Metal hydroxides are commonly added into polyolefins to produce halogen free compound. The most widely used in the fiber cable industry are aluminum trihydrate and magnesium hydroxide with ethylene vinyl acetate copolymer and polyethylene copolymers.
Coated Steel Armor
The coated steel armor is composed of thin low carbon steel which is coated on both sides with a metal adherent copolymer.
PVC Compatible Coated Steel
A new coating system with a unique copolymer was developed to be compatible with PVC. The more elastic properties of the PVC compatible coating results in an apparently lower peel strength but overall the properties are comparable.
Halogen Free Compatible Steel
The standard copolymer coated steel is adhesively compatible with the commercially available HFPO compounds.
Other Types of Armored Fiber Cables
Armored cable is also available with a double-armor protective jacket for added protection in harsh environments. The steel armor should always be properly grounded to an earth ground at all termination points, splice locations and all building entrances.