Blowing air through fiber optic cables

The air blowing method installs fiber optic cables by using high-speed airflow combined with mechanical pushing to propel the cable through pre-installed ducts efficiently and safely.

Overview of the Method

The air blowing method, also called jetting, involves feeding the fiber optic cable into a pre-installed conduit and using compressed air to push the cable along the duct. A blowing head attaches to the cable, creating a seal that allows air pressure to propel the cable while minimizing friction between the cable and duct walls . This method is preferred over traditional pulling because it reduces labor, installation time, and the risk of cable damage, especially over long distances or ducts with multiple bends .

Equipment Required

• Air Compressor: Generates the high-speed airflow needed to move the cable.
• Blowing Head: Attaches to the cable and ensures a tight seal for efficient air propulsion.
• Cable Blowing Machine: Often includes a hydraulically powered belt system to control cable feed and maintain smooth installation .
• Ducts/Conduits: Pre-installed pipes through which the cable is blown. The conduit should be slightly larger than the cable to reduce friction and air pressure requirements .
• Optional Lubricants: Low-friction lubricants can be applied to further reduce resistance and protect the cable jacket .

Installation Procedure

1. Preparation: Ensure the duct is clean, dry, and free of obstructions. Plug ducts to prevent water entry. Check cable and reel for defects.
2. Cable Feeding: Attach the cable to the blowing head and feed a few hundred meters into the duct manually or using a tractor mechanism .
3. Air Injection: Start the air compressor to inject high-speed air into the duct. The air flow creates a floating effect, reducing contact with the duct walls and minimizing friction .
4. Mechanical Assistance: The cable is pushed near the duct inlet using rollers or a belt system to assist initial movement .
5. Monitoring: Continuously monitor air pressure, cable speed, and duct integrity to prevent damage. Use minimum pressure necessary to avoid cable jacket stress .
6. Completion: Once the cable reaches the end of the duct, secure it and remove the blowing head. Check for any damage or kinks.

Best Practices

• Use low-friction cables and ensure the conduit is slightly oversized relative to the cable diameter .
• Avoid excessive air pressure to prevent cable damage.
• Consider temperature effects: cold cables or air can make the jacket brittle or cause condensation and freezing .
• For long runs, mid-assist devices can be used to extend installation distances beyond 1,500–2,000 meters .
• Stiffer cables are preferable for straight ducts, while flexible cables perform better in ducts with multiple bends .

Advantages

• Faster installation over long distances.
• Reduced labor and manpower requirements.
• Lower risk of cable damage compared to traditional pulling.
• Ability to install microduct and armored cables efficiently . The air blowing method is widely used in modern fiber optic deployments due to its efficiency, safety, and adaptability to various duct configurations and cable types. Proper equipment selection, careful monitoring, and adherence to best practices ensure successful installations.