What is the diameter of the fiber used in an air blown fiber installation?

• A. 125 μm
• B. 250 μm
• C. 500 μm
• D. 900 μm

Answer: (B)

Air blown fiber installations use microfibers that are around a quarter of a millimeter in diameter. This small size, typically a coated fiber with about 125 μm of glass plus polymer coating bringing the total to roughly 250 μm, lets the fiber move through the microduct with air while the coating protects the glass from damage during blowing and handling. A bare 125 μm fiber would be too fragile to push long distances, and fibers on the order of 500 μm or 900 μm are too large for the microduct system, creating excessive friction and needing bigger conduits. So the standard blown fiber diameter is about 250 μm.