By TEBAOFLEX Jyen. Originally published on February 18, 2026.
Treat cable, duct and installation equipment as a system
Air blowing combines mechanical feeding with aerodynamic drag distributed along the cable. It can reduce the tension accumulated when pulling a cable from its far end, but it does not remove every friction or buckling mechanism. Route bends, undulation, cable stiffness, duct condition and leakage can still limit the achievable length.
IEC 60794-5-10:2014 is a family specification for outdoor microduct optical fibre cables and associated microducts intended for blowing. Citing it does not establish a guaranteed installation distance, a universal compressor setting or an approved combination of any two products.
State exactly which fill ratio you mean
For a round cable of outside diameter d in a round duct of inside diameter D, define the diameter ratio as d/D. The occupied cross-sectional area ratio is (d/D)². Both quantities are useful, but a percentage without its definition can create a serious sizing error.
Hypothetical example: a 5.2 mm cable in an 8.0 mm bore has a diameter ratio of 65%, an area ratio of 42.25%, and a nominal radial clearance of 1.4 mm before tolerances or ovality. This arithmetic is not a validated cable/duct pairing or a blowing-distance prediction.
Select from the cable and duct manufacturers’ compatibility guidance. Excessively small clearance can restrict airflow and magnify the effect of bends; a slender flexible cable in a large bore may be difficult to feed without buckling. There is no universal 50–75% diameter window that guarantees every installation. Include maximum cable diameter, minimum duct bore, joints, ovality and local restrictions in the assessment.
Reduced coating diameter: useful density, not a smaller glass core
The 180 µm, 200 µm or 250 µm description commonly refers to the coated fibre diameter. The nominal 125 µm dimension refers to glass cladding, not the light-guiding core. Optical compatibility depends on the fibre specification and mode-field properties as well as the glass dimensions.
For an ideal circular coated fibre, reducing diameter from 250 µm to 200 µm reduces its occupied area by 1 − (200/250)² = 36%. Reducing it to 180 µm gives 48.16%. These geometric examples do not imply the same percentage reduction in complete cable diameter or a guaranteed doubling of fibre count: tubes, strength members, clearances and sheath still occupy space.
Sirocco, SiroccoHD and SiroccoXT are Prysmian product families, not TEBAOFLEX proprietary models. Manufacturer data illustrate how reduced coating and tube designs can increase density. Use the exact regional part number and current drawing rather than transferring dimensions between generations or variants.
Prepare the route and control the installation
- Verify duct continuity, cleanliness, joints, pressure rating and route geometry using the approved installation method.
- Match the blowing head, seals, drive settings and compressor to the cable and duct; use their lowest applicable pressure and force limits.
- Control air quality and temperature as specified by the equipment and material suppliers; do not adopt a blanket 12–15 bar setting.
- Provide a safe discharge/end-point arrangement and exclusion zones. Depressurize before opening connections or clearing obstructions.
- Record pressure, flow, feed force, speed, route and stoppages during a representative trial; use these to plan access points and installation sections.
Acceptance after blowing
Check the installed optical path with the specified loss and reflectometry procedures, including appropriate reference leads and bidirectional measurements when required. Follow fibre-specific stripping, cleaving and splicing instructions. A common cladding diameter does not guarantee a splice loss below 0.05 dB.
Hybrid power-fibre and tactical surface cables introduce additional electrical, mechanical and connector requirements. They are not automatically suitable for microduct blowing merely because their outside diameter fits. Obtain a documented compatibility and acceptance plan before installation.
Sources and application documentation
Discuss the application
Send the application duty, installation drawing and required acceptance criteria to TEBAOFLEX. WhatsApp: +86 185 9591 3361. Request the applicable product documentation before ordering.