INTRODUCTION TOFIBRE BLOWING

Gavin PetersSales Director - Mills Ltd

What Is Fibre Blowing?

Fibre blowing is a technique to install cables in ducts or microducts and is an alternative to traditional cable pulling.

It is achieved by blowing the cable through a duct while simultaneously pushing the cable.

Traditional Cable Pulling

Traditionally, fibre optic cables were pulled through cable ducts in the same way as copper cables, via a winch line. A pre-installed draw rope is required inside the duct to attach the cable at one end and the winch at the other.

Every time a bend or undulation in the duct is passed the pulling force is multiplied by a friction dependent factor.

This means that the greater the local pulling force is, the greater the amount of friction that the cable will experience (while being pulled against the internal duct wall). This "capstan effect" leads to an exponential force build-up with pull distance, producing undesirably high pulling forces.

How Fibre Blowing Works

Compressed air is injected at the duct inlet and flows through the duct and along the cable at high speed.

The high speed air propels the cable due to drag forces and pressure drop. The friction of the cable against the duct is reduced by the distributed airflow, and large forces that would generate high friction are avoided.

Because of the expanding airflow, the air propelling forces are relatively small at the cable inlet and large at the air exhaust end of the duct.

To compensate for this, an additional pushing force is applied to the cable by the blowing machine which increases the maximum blowing distance significantly.

Why Blow Fibre?

The benefits of blowing over pulling fibre are:

•Longer installation distances can be achieved

•Installation distance is less dependent on bends and undulations in duct

•Forces exerted on the cable are lower

•The step of pre-installing a winch rope into the duct is avoided

•Equipment is needed only at one end of the duct route

What Equipment Is Required?

Microflow Touch Miniflow MultiflowPowerflow

Determining Which Blowing Machine To Use

Outside Ø

5-16mm 7-20mm 18-70mm 18-70mm

Outside Ø0.8 - 5.5mm

4 - 12mm 8 - 25mm 8 - 32mm

Up to 2km Up to 2.5km Up to 5km Up to 5km

Typical Application

FTTB / FTTH/Last mile

FTTCSpine cables

over long distance

Relining ducts

A B

•Toolkits

•Tool cases, boxes & wallets

•General Hand Tools

•Cable Preparation & Termination Tools

•Power Tools & Cutting Tools

•Contractors Tools & Site Equipment

•Cable Handling Equipment

•Safety Equipment

•Fibre Optic Tooling

•Test Equipment

Associated Installation Equipment

•Tensioners, Straps & Chains

•Pole Lifting, Handling & Installation Equipment

•Pole Furniture & Fittings

•Cable Pulling & Guiding Equipment

•Manhole Furniture

•Cover Lifting Keys & Equipment

•Propane Equipment

•Resins & Compounds

•Pressurisation

•Closures, Sleeves & Duct Sealing

Associated External Overhead & External Underground

Equipment

Structured Cabling, Cable Management & Specialist Tooling For The Communications Industry

If you require any further information, please contact me:

Gavin Peters – Sales Director

Mills Ltd13 Fairway DriveFairway Industrial EstateGreenfordMiddlesexUB6 8PWUnited Kingdom

Tel: 0777 4281000email: gavin.peters@millsltd.com