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MicroDucts Solutions--Introduction of MicroDucts

DATE:2022-11-18   VISITS:133


1. What is a MicroDucts?
MicroDucts is a key component in the access network, and its function is to transmit information. The optical transmission index of MicroDucts is the same as that of ordinary optical cable. Because its outer diameter is thinner than that of ordinary optical cable, it is referred to as micro cable for short.

MicroDucts can be installed in tiny pipes without excavating the road surface through air blowing installation technology, or can be installed in pipes of existing optical cables, saving pipe resources and meeting the real-time expansion requirements of the network.

Its anti-side pressure and anti-flexion design have good air-blowing installation performance. And the optical cable is small in size, light in weight, high in fiber density, and has excellent temperature performance and can withstand the test of different temperatures.

OPF is an optical fiber manufacturer in China and has produced Microducts for many of our customers. For more information, please contact us: bella@o-pf.com.


2. The structure of the micro-cable

The factors that should be considered in the construction of micro-cable mainly include:

Low thermal expansion and contraction rate and temperature coefficient; low friction coefficient and moderate hardness; cable attenuation cannot be increased after air-blown cable laying. In order to adapt to this use, the micro-cable must have a corresponding structure. The structure of the common micro-cable is as follows

(1) Steel tube micro-cable

Steel pipe micro-cable · The micro-cable of the steel pipe structure has a seamless stainless steel pipe in the middle. The steel pipe has optical fibers and is filled with waterproof compounds. A layer of HDPE sheath is applied outside the steel pipe, and the maximum number of cores can reach 72 cores. Seamlessly welded steel tube prevents water or other substances from penetrating light

(2) All-dielectric micro-cable

All-dielectric micro-cables and all-dielectric micro-cables are non-metallic cables. They are filled with waterproof compounds to play the role of longitudinal waterproofing. The maximum number of cores can reach 60 cores. It is especially suitable for backbone network access network and optical fiber to outdoor sheath.

(3) Fiber bundles

Fiber optic bundles currently commonly used fiber bundles include high-performance fiber units EPFU and MHT fiber bundles. The diameter of EPFU fiber bundles is very small, and is generally used for wiring inside buildings. In order to enhance the air blowing effect, a layer of acrylic material is added to the outer skin. Very fine glass particles. These particles reduce the coefficient of friction and increase the drag of the airflow


3. Factors affecting the air blowing effect of micro-cable

(1) Influence of the hardness of the micro cable on the cable laying
If the micro-cable is too soft, it and the inner wall of the micro-tube will generate greater frictional resistance; if the micro-cable is too stiff, the micro-cable will also generate greater frictional resistance at the turns of the micro-tube, resulting in a decrease in the air blowing length. In addition, the memory strength of the micro-cable when it is rolled into the cable reel can also affect the length of the air-blown micro-cable. After the micro-cable with weak memory is pulled from the cable reel, it can immediately resume the straight state, but after the micro-cable with strong memory is pulled from the cable reel, it always maintains the spiral state when it is wound around the reel. The air blowing effect of the weak micro-cable is much better than the air blowing effect of the strong memory. Because the helical microcable enters the microtubule, it will increase the contact area with the inner wall of the microtubule and the force on the inner wall of the microtubule, resulting in additional frictional resistance. In addition, the drag force of the airflow acting on the micro-cable will also decrease.
(2) Influence of appearance size on cable laying

The space between the micro-pipe and the micro-cable is very small, and the protrusion on the outer sheath of the micro-cable will cause the failure of the cable and the instability of the air flow, so it is not necessary to any irregularities in the shape of the micro-cable are allowed

(3) Influence of friction coefficient on cable laying

The friction coefficient has a great influence on the cable laying, and the pipeline without lubrication will cause the micro-cable to have high frictional resistance in the micro-pipe, resulting in the decrease of the speed. The lubrication of the micro-cable can improve the air blowing effect. In the case of high frictional resistance of the pipeline, if the micro-cable is lubricated at the robot port, the length of the cable can be significantly increased, but it is also easy to cause the micro-cable to slip in the machine.

4. The advantages of MicroDucts

Compared with the traditional layer-stranded optical cable, the material consumption and processing cost of the micro-cable with the same number of cores are greatly reduced.

The structure size is small, the wire quality is small, the weather resistance is good, and the optical cable can be reused.

The bending performance is good, and the micro-optical cable has good lateral pressure resistance under normal working conditions.

It is suitable for overhead and pipeline laying, and a reinforced steel rope with a smaller size can be used for overhead laying. Existing piping resources can be saved when piping is laid.


5. What is air-blown micro-cable

The typical structure of the air-blown micro-cable system is parent pipe-micro-pipe-micro-cable, the parent pipe can be placed in the concrete pipe hole, and new routing construction can also be carried out. In the laid HDPE or PVC main pipe, or pre-lay the main pipe and micro pipe on the route of the new optical cable, it can be passed through the pipe or blown with a cable blower. The number of microtubes that can be placed in the parent tube mainly depends on the requirements of mechanical protection. The sum of the cross-sectional areas of the microtubes (calculated by the outer diameter of the microtubes) shall not exceed half of the cross-sectional area of the parent tube. Fill the microtube with continuous airflow, and use the air flow in the pipeline to push and pull the surface of the microcable to distribute the microcable into the microtube.
The microtubules are usually blown into the mother tube in bundles at one time. Due to the high-pressure airflow, the optical cable will be in a semi-suspended state in the pipeline, so the change of terrain and the bending of the pipeline have little effect on the cable laying. The micro-cable is blown into the micro-tube by the air blower, and it can blow 1.6km at a time. In this special construction environment, the micro-cable should have appropriate rigidity and flexibility, the friction between the outer surface and the inner surface of the micro-tube should be small, and the shape and surface morphology of the micro-cable are conducive to generating a larger push-pull force under the airflow , microcables and microtubes have mechanical properties suitable for blowing in microtubes, environmental properties, and optical and transmission properties suitable for system requirements.
6. Advantages of air-blown micro-cable

The Air-blown Micro Cables method is an outdoor optical cable laying technology with excellent mechanical properties and strong protection function. It is suitable for all levels of the network and has the following advantages:

(1) The optical fiber assembly density is high, and the tube hole resources are fully utilized by laying reusable sub-tubes.

(2) It can be used for newly laid HDPE main pipes or existing PVC main pipes, and can be connected to new users without affecting the normal operation of the opened optical cables.

(3) It can be blown into the optical cable in batches with the growth of communication traffic to meet the needs of users in time. It is convenient to adopt new types of optical fibers in the future and maintain technically.

(4) The air blowing speed of the micro cable is fast and the air blowing distance is long, and the laying efficiency of the optical cable is greatly improved.

(5) It is easy to expand the capacity in parallel and vertically, reduce the workload of digging trenches, and save the cost of civil engineering. 

For more information, please contact us: bella@o-pf.com.

Center Tube Layer Microduct Optical Cable.png


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