Air pressure in optical fiber cable

Air pressure in optical fiber cable installation typically ranges from 10 to 15 bar, enabling the cable to float inside the duct and reducing friction for efficient blowing or jetting.

Role of Air Pressure

Air pressure is critical in air-assisted installation techniques such as cable blowing and jetting. Compressed air is injected into the duct to create a high-speed airflow that “floats” the cable, minimizing contact with the duct walls and reducing friction. This allows longer cable lengths to be installed with less mechanical stress and lower risk of damage to the cable jacket or buckling at bends .

Typical Pressure Ranges

• Short distances or smaller cables: 10–13 bar is generally sufficient for ducts with simple routes and minimal bends .
• Longer distances or larger/heavier cables: 13–15 bar is recommended to overcome additional friction, bends, slopes, and complex duct layouts .
• Microducts: 10–12 bar is common, with a maximum of 16 bar depending on the jetting machine and duct size . The air pressure must be stable and high enough to generate sufficient drag force to move the cable smoothly through the duct. Insufficient pressure can slow installation or cause the cable to get stuck .

Airflow Considerations

Along with pressure, airflow volume is important. Typical airflow ranges from 10 to 15 cubic meters per minute, depending on cable diameter, weight, and duct size. Larger or heavier cables require higher airflow to maintain the floating effect . Compressed air is often cooled to near ambient temperature to prevent overheating and maintain efficiency.

Installation Best Practices

• Perform a crash test to determine the maximum pushing force without damaging the cable jacket .
• Use a cable reel pay-off to avoid rubbing against drum flanges and ensure smooth cable entry into the duct .
• Select a compressor matched to the blower and project requirements, ensuring it can deliver the necessary pressure and airflow for the cable type and duct layout .

Summary

Maintaining the correct air pressure (10–15 bar) and airflow is essential for efficient, safe, and long-distance optical fiber cable installation. Proper compressor selection, duct preparation, and adherence to installation best practices ensure minimal friction, reduced mechanical stress, and faster deployment of fiber networks .