Plastic Ducts (PVC/HDPE): The most common option, ideal for urban areas. PVC ducts are cost-effective and resist corrosion, while HDPE (high-density polyethylene) adds flexibility and impact resistance—perfect for areas with soil movement.
Steel Ducts: Used in industrial zones or high-security areas (e.g., near power plants). Steel provides exceptional physical protection against rodents, construction damage, and extreme pressure.
Concrete/Asbestos Cement Ducts: Legacy options still found in older urban networks. Concrete offers durability but is heavy and rigid, making it less suitable for new installations.
Fiberglass-Reinforced Plastic (FRP) Ducts: Lightweight, non-conductive, and resistant to chemicals—ideal for coastal regions (saltwater corrosion) or areas with high lightning risk.
Optical Fibers: Single-mode (e.g., G652D, G657A1) or multimode (e.g., OM3, OM4) fibers, depending on bandwidth and distance needs.
Buffer Tubes: Gel-filled or dry tubes that house individual fibers, blocking moisture and reducing microbends.
Strength Members: Aramid yarn (e.g., Kevlar), steel wires, or fiberglass rods that resist tension during installation (prevents fiber stretching).
Outer Jacket: Materials like LSZH (Low Smoke Zero Halogen), PE (polyethylene), or PVC, chosen for flame resistance, UV protection, or chemical resistance.
Armor (Optional): Steel tape (GYTS) or aluminum tape (GYTA) for extra durability in high-risk ducts (e.g., near construction sites).
Moisture Resistance: Gel-filled buffer tubes or dry water-blocking tapes prevent water ingress—critical for underground ducts in rainy regions.
Rodent and Pest Defense: Ducts and armor (e.g., steel tape) shield fibers from gnawing rodents, a common issue with direct-burial cables.
Temperature Stability: Jackets and buffer materials withstand extreme temperatures (-40°C to +85°C), making duct fiber suitable for both cold climates (e.g., Canada) and hot, humid areas (e.g., Southeast Asia).
Physical Damage Mitigation: Ducts absorb impacts from construction or soil movement, while the cable’s strength members prevent stretching or crushing during installation.
Easy Access: Technicians can pull existing cables out of ducts or add new ones without digging—reducing downtime and disruption to roads, sidewalks, or landscaping.
Scalability: Ducts often have extra space (“conduit spare capacity”) to add more fiber cables as network demand grows (e.g., upgrading from 10G to 100G).
Faster Repairs: If a cable is damaged, replacement cables can be pulled into the duct in hours, not days—critical for telecom networks with strict uptime requirements.
Bandwidth Capacity: Single-mode duct fiber supports 100G, 400G, and even 800G speeds—ideal for telecom backbones and data center interconnections (DCI).
Low Signal Loss: The cable’s structure minimizes microbends and attenuation, enabling transmission distances of 100km+ for single-mode fiber (without amplification).
Compatibility with WDM Technologies: Duct fiber works seamlessly with DWDM (Dense Wavelength Division Multiplexing) and CWDM (Coarse WDM), allowing operators to transmit multiple signals over one cable—maximizing duct space.
No Excavation: Avoiding digging reduces soil disruption, preserves green spaces, and cuts down on construction-related emissions.
Reusable Infrastructure: Ducts can be used for decades, and cables can be replaced or upgraded without replacing the duct itself—reducing waste.
Backbone Cabling: Duct fiber forms the “spine” of urban telecom networks, linking central offices (COs) to cell towers, data centers, and distribution points.
Smart City Infrastructure: Powers smart traffic lights, IoT sensors, and public Wi-Fi—ducts hide cables from view, maintaining urban aesthetics while ensuring reliable connectivity.
Underground Transit Systems: Installed in subway or metro tunnels to connect communication systems (e.g., passenger Wi-Fi, train control) without disrupting rail operations.
Last-Mile Distribution: Duct fiber runs from neighborhood distribution cabinets to building entrances, where it connects to drop cables (smaller fibers that enter homes).
Multi-Dwelling Units (MDUs): In apartments or condos, duct fiber is routed through building ducts to avoid drilling holes in walls—simplifying installation and reducing tenant disruption.
Low-Latency Links: Duct fiber’s low attenuation ensures minimal latency, critical for real-time applications like cloud computing and high-frequency trading.
Scalable Capacity: Extra duct space allows data centers to add more fiber as they expand, supporting 400G/800G links for AI and big data workloads.
Power Grids: Installed in ducts alongside power lines to connect substation communication systems—non-metallic duct fiber (e.g., GYFTY) avoids interference from high-voltage lines.
Oil and Gas Facilities: Used in refineries or offshore platforms (in protected ducts) to transmit sensor data and control signals—resistant to chemicals and extreme temperatures.
Airports and Ports: Duct fiber connects baggage handling systems, security cameras, and passenger information displays—ensuring uninterrupted operations.
Prep the Duct: Inspect the duct for blockages (e.g., debris, collapsed sections) and clean it with a duct brush if needed. Install lubricants (dry or gel-based) to reduce friction between the cable and duct walls.
Install a Pull Rope: Use a “duct rodder” (a flexible rod) to thread a pull rope through the duct. Attach one end of the rope to the cable’s strength member (never the fiber itself).
Pull the Cable: Use a manual winch (for short runs) or an electric traction machine (for longer runs) to pull the cable at a steady speed (typically 1–3 meters per second).
Secure the Cable: Once the cable is in place, secure it at both ends (e.g., to cable management brackets) and test for signal loss.
Low equipment cost (no specialized compressors needed).
Fast setup for short ducts (≤500 meters).
Suitable for ducts with tight bends (since pulling force can be controlled).
Risk of tension damage if pulled too hard (can stretch fibers, increasing attenuation).
Not ideal for long ducts (≥1000 meters) or ducts with many obstacles.
Residential FTTx deployments (short duct runs to buildings).
Retrofits of small urban ducts (e.g., in older neighborhoods).
Duct Inspection and Prep: Same as the pulling method, but ducts must be leak-tight (air pressure is critical). Install a “blowing head” (a specialized fitting) at the start of the duct.
Connect the Cable: Attach the cable to the blowing head, which creates an air seal around the cable. The blowing head connects to a high-pressure air compressor (typically 6–10 bar).
Blow the Cable: Turn on the compressor—air flows through the duct, creating a pressure difference that pushes the cable forward. A “cable feeder” feeds the cable into the duct at a speed matching the air flow (2–5 meters per second).
Test and Secure: Once the cable reaches the end, disconnect the blowing head, secure the cable, and test for signal integrity.
Minimal tension (air pressure does the work, reducing fiber damage risk).
Suitable for long ducts (≥1000 meters) and ducts with multiple bends.
Faster installation (can cover 1km in 5–10 minutes).
Higher equipment cost (compressors and blowing heads are specialized).
Requires leak-tight ducts (air loss reduces efficiency).
Telecom backbones (long duct runs between cities).
Data center DCI links (large ducts with high-capacity cables).
Urban smart city projects (complex duct networks under roads).
Structure: Steel tape armor (S) around the cable core, with a PE outer jacket.
Key Benefit: Exceptional physical protection—resists crushing, rodent damage, and impact.
Use Case: Industrial zones, construction areas, or ducts near heavy machinery (e.g., ports, factories).
Structure: Aluminum tape armor (A) with a PE jacket.
Key Benefit: Superior moisture resistance (aluminum blocks water) and lighter weight than GYTS.
Use Case: Underground ducts in rainy regions (e.g., coastal cities) or damp industrial facilities.
Structure: Non-metallic (F = fiber-reinforced plastic) armor, no metal components.
Key Benefit: Lightning-resistant and non-conductive—ideal for ducts near power lines or in lightning-prone areas (e.g., rural telecom networks).
Use Case: Power grid infrastructure, outdoor ducts in storm-prone regions (e.g., Florida, Southeast Asia).
Structure: No armor, just a thick PE jacket and strength members (aramid yarn).
Key Benefit: Flexible and lightweight—easy to pull through small ducts or ducts with tight bends.
Use Case: Residential FTTx ducts (small diameter), indoor ducts (e.g., in office buildings).
Structure: Non-metallic armor (FRP) with a steel tape layer for extra durability.
Key Benefit: Balances non-conductivity (lightning protection) and physical strength.
Use Case: Mixed environments (e.g., urban ducts that pass near power lines and construction zones).
Fiber Type:
Single-mode: G652D (standard long-haul), G657A1 (bend-insensitive for tight ducts), G657A2 (ultra-bend-insensitive for small ducts).
Multimode: OM3 (10G up to 300m), OM4 (10G up to 550m), OM5 (wideband for SWDM).
Fiber Core Count: 1–512 cores (or more for large-scale telecom backbones).
Tension and Crush Resistance:
Short-term tension: ≤1000N (residential) to >5000N (industrial).
Short-term crush resistance: ≤1000N/10cm (light use) to >5000N/10cm (heavy industrial).
Jacket Material:
LSZH: Flame-retardant, low smoke/toxicity—ideal for indoor ducts (e.g., hospitals, schools).
PE: UV-resistant and moisture-proof—best for outdoor ducts.
PVC: Cost-effective for indoor ducts with no flame requirements (e.g., office buildings).
Armor Type: Add steel, aluminum, or FRP armor based on environmental risks (e.g., steel for rodents, FRP for lightning).
Consultation: Share your project details (environment, duct size, bandwidth needs, local regulations) with a cable engineer.
Design: The engineer creates a custom cable blueprint, including material selections and performance specs.
Prototyping: A small batch of cables is manufactured and tested (for attenuation, tension, crush resistance) to ensure compliance.
Production: Once the prototype is approved, full-scale production begins—with quality checks at every stage.
Delivery and Support: The cables are shipped with installation guides, and technical support is provided to ensure smooth deployment.
Moisture: Choose GYTA (aluminum armor) or water-blocking tapes.
Rodents/Impact: Opt for GYTS (steel armor) or GYFTS.
Lightning: Use non-metallic GYFTY.
Short-distance (≤500m, 10G): Multimode OM3/OM4.
Long-distance (≥1km, 100G+): Single-mode G652D/G657A1.
Pulling: Flexible cables like GYTY (no armor) are easier to pull.
Air Blowing: Heavier armored cables (GYTS/GYTA) work well, as air pressure handles the weight.
Add extra fiber cores (e.g., 48 cores instead of 24) to accommodate future upgrades.
Choose ducts with spare capacity to add more cables later.
