7 important points to blow fiber optic cable far away

7 important points to blow fiber optic cable far away

7 important points to blow fiber optic cable far away, let’s take a look in deep on important cable blowing tips. Cable blowing is the process of blowing the cables into telecom ducts with the help of pressurized air. Airflow helps you to carry the cable through ducts. What distance can you blow a cable into duct? This is not an easy question to answer as there are many important factors and criteria; fill-ratio of ducts, cable blowing machine and its quality and power, duct installation and its route, weather conditions, experience of machine operator, lubrication oil usage or non-usage (friction), cable flexibility etc..

Here we will give you some tips to blow your cables further with cable blowing machine, whether it’s on speed or distance, here are 7 tips to remember


7 important points to blow fiber optic cable far away


  1. The priority is safety – 7 important points to blow fiber optic cable far away

As a fiber blowing technician, you can’t improvise! For cable blowing and preparation procedures, everyone involved must be trained. A quick reminder of the most important safety requirements for you and your team:

  • Protect yourself by using eye protection, ear muffs, a helmet, and a protective suit. Local regulations and company safety norms apply, however we strongly advise that you use them to avoid injuries.
  • Test the communication between the several working stations before starting the machines: safety warnings such as “STOP” or “RUN” must be completely understood.
  • Before performing any work on the connections, turn off the air pressure between the compressor and the blowing machine.
  1. You must use the suitable duct size and cable size. Cable Blowing Tips

The diameters of the cable and duct must be compatible. The percentage of fill ratio should be between 30 and 50 percent to ensure that your cable is suitable with the duct. Performances are definetely  affected if sizes are below and above the specified limits.

When blowing cables, the fill ratio is calculated using areas, or d/D. For maximum performance while cable blowing, UPCOM advises using simple diameters to calculate the fill ratio, with a target range being 50% to 80%.

Percentage of occupation = (cable OD)² / (duct ID)²
The easy calculation is:   0.5*(duct ID)  < (cable OD) < 0.7*(duct ID)

”cable OD” stands for “Cable Outer Diameter”
“duct ID” stands for “Duct Inner Diameter”

  1. Be careful with your cable

Place the cable drum on a pay-off and make sure the cable will be protected against water, sun and dust while blowing. Mount a cap on the head of the cable. This cap prevents air penetration into the cable at high pressure and ensure there will be no rough contact between the cable head and the tube or the connectors.

  1. Check your cable blowing machine

The machine must be adjusted and setted up properly to the cable and the duct you have. Here is a listing of the primary questions you shall ask yourself:

  • Are the blowing machine, accessories (Cable Seal, Nutring and Duct Connection tools) and compressor suitable for the current cable and duct?
  • Is it possible to reach the right level of air flow and pressure? The use of a lubrication oil is recommended.
  • Do I have connections of the right type for this installation job?
  • Is my stand (pay-off) suitable for the drum size?

It is good to note that between the compressor and the blowing machine, a drier and an air cooler equipment will help you to reach the greatest results.

  1. Duct condition to be checked

When the duct has passed the gauge test, clean it to remove moisture and dirt. The best way to do so is to use sponges made for this purpose. If it is not possible to get a clean and dry duct even by repeating this operation, the duct shall be considered as inappropriate for blowing.

The quality and installation of the duct (and its accessories) are the key to a smooth and easy path without wave effects: a perfect installation should be done without bending in order to achieve the maximum blowing distance. It’s not that easy in the field and all other turns on the route affect the blowing distance. Also, be careful with the connectors as they are not designed to plug ducts in a bend.

To check the correct condition of the duct, first make sure that the outer end of the duct is secured with a trap. Then use a measuring device to check that the duct was not damaged during installation. This gauge should have a diameter that is slightly smaller than the inside diameter of the duct. A ball chain is effective for this process. It should take less than 15 minutes each. km channel at a maximum of 8 bar to complete this process. Otherwise there is a suspicion of pipelines.

After the channel passes the gauge test, clean it to remove moisture and dirt -sponges made for this purpose-. If even by repeating this process it is not possible to obtain a clean and dry canal, the canal must be considered unsuitable for blowing.

  1. Use lubricant 

Special lubricants have been developed for cable jetting to further reduce friction. Even if lubrication is time consuming, it is also a warranty of good performance and eventually of efficiency. When distance is short, lubrication can be skipped. Use the lubricant recommended by the duct manufacturer.

The quantity of lubricant must be adapted to the duct size and length, as for the provider’s recommendation. Spread the lubricant by blowing a foam carrier through the duct.

  1. Follow the blowing procedure

We recommend to start pushing the cable at a speed between 40 and 60 m/min, without air pressure in the duct. When the speed begins to decrease, open the air inlet valve of the blowing machine to reach a pressure between 1 and 2 bars in the duct. Speed goes up to the previous value. If cable does not speed up, increase the pressure by steps of 1 bar.

All along the blowing operation, adjust the cable pushing force to regulate the rate of progression of the cable in the duct.

What to do when you cannot progress anymore, and if the target is almost achieved?

  • Stop the machine and release the air pressure in the tube.
  • After 5 minutes, open the air flow until the maximum air pressure is reached.
  • After a few minutes, restart the machine to push the last meters.
  • Repeat if necessary.


These are some cable blowing tips important to remember. Below you can find some setup videos of our machines;

Cable Blowing Tips


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