Air blowing of optical cables

Air blowing, or jetting, is a method of installing optical fiber cables into pre-laid ducts using high-speed compressed air combined with mechanical pushing, enabling long-distance, low-friction deployment.

Overview of Air Blowing

Air blowing, also called blown fiber installation, involves inserting optical fiber cables into pre-installed ducts or micro ducts using compressed air to propel the cable forward. The process typically starts by pushing a few hundred meters of cable into the duct using a mechanical pusher or tractor mechanism. Once the cable is partially inserted, high-velocity airflow is introduced, which suspends the cable inside the duct, reducing friction and allowing it to travel long distances with minimal mechanical stress .

How the Process Works

1. Cable Preparation: The fiber optic cable is attached to a blowing head with seals that grip the cable tightly. The cable is designed with a low-friction outer jacket to facilitate smooth movement .
2. Mechanical Pushing: A pushing device or tractor mechanism applies force near the cable inlet to start the insertion.
3. Compressed Air Injection: Compressed air (typically 8–12 bar) is injected into the duct, creating a high-speed airflow that propels the cable forward. The airflow partially suspends the cable, reducing contact with the duct walls and minimizing strain .
4. Cable Floating: The cable “floats” inside the duct, allowing it to navigate bends and undulations efficiently. Stiffer cables perform better in straight ducts, while more flexible cables handle complex routes .

Advantages Over Traditional Pulling

• Longer Installation Distances: Air blowing can install cables over 1–2 km in a single run, reducing the need for splicing .
• Reduced Strain: The cable experiences lower mechanical tension compared to pulling, preserving fiber integrity.
• Smaller Ducts: Micro ducts of 10–20 mm can be used, compared to 50–100 mm for traditional conduits .
• Lower Labor and Equipment Costs: Fewer technicians and lighter equipment are required, reducing installation time and cost by 30–60% .
• Scalability: Empty micro ducts can be installed first, and cables can be blown in later as needed, supporting phased network rollouts .

Applications

Air blowing is widely used in:

• FTTH (Fiber to the Home) deployments
• 5G/6G backhaul networks
• Data center interconnects
• Rural broadband projects
• High-rise and urban environments where traditional pulling is impractical

Practical Considerations

• Duct Size: Choose a duct slightly larger than the cable to reduce required air pressure.
• Air Pressure: Use the minimum pressure necessary to avoid damaging the cable.
• Temperature: Avoid extreme cold, which can make the cable jacket brittle or cause condensation in the duct .
• Cable Design: Low-friction jackets and appropriate stiffness are critical for optimal blowing performance . Air blowing has become the preferred method for modern fiber optic deployments due to its efficiency, scalability, and ability to handle high-fiber-count cables in challenging environments.