1. What is air blown fiber cabling system?
The air-blown optical fiber system is to pre-lay special fiber-blown micro-tubes and accessories in the early stage of integrated wiring. When the optical fiber needs to be installed, the optical fiber is blown into the empty optical fiber micro-tube through compressed air. In the future, when the network infrastructure completes the life cycle and needs to be upgraded, it enables it to provide a non-destructive upgrade way, which is a brand new and future-proof cabling system.
There are two types of air-blown fiber optic systems. In the first, 2-12-core fiber optic cables are manufactured into 1.1-2.0mm, which we call enhanced performance fibre units (EPFU), which are mainly used in indoor scenarios such as buildings. In the second, the fiber optic cable up to 288 cores is manufactured into 4.0-10.5mm, we call it microcable or minicable, which is mainly used to solve the bottleneck problem in the future network and build a more flexible and easier-to-manage fiber optic cable network.
2. Development of air-blown optical fibers
- In 1982, British Telecom invented the air-blown optical cable technology, but due to the blowing technology and other reasons, it has never been commercialized.
- In 1987, Brand-Rex company invented the single-air-blown optical fiber technology for local area networks.
- In 1988, the installation of indoor air-blown optical fiber was realized for the first time.
- In 1993, the whole system was developed and perfected, officially named as air-blown fiber optic cabling system and started commercialization. Blolite is the brand logo of the air-blown fiber optic cabling system of the famous cabling manufacturer Brandray.
- At the end of the 20th century, the new headquarters of AT&T Corporation in the United States chose the air-blown optical fiber system to support its high-speed local office network. After nearly 30 years of application and development, the air-blown optical fiber system has been more and more accepted by the LAN application market. There is an association on air-blown fiber optic systems in Europe, and there is interoperability and compatibility between air-blown fiber optic systems from different manufacturers.
- Air-blown optical fiber cabling system has developed from a new thing to an important part of the optical fiber application system. It is not only mature and reliable but also proved to be completely stable and excellent after years of testing.
3. Component of air-blown fiber optic wiring system
The air-blown fiber system consists of microtubes (single microtubes and multi-microtubes), air-blown fiber cores (single-mode or multi-mode fibers, and can be equipped with standard ST or SC interfaces), accessories (including patch panels, information outlet, connecting head, etc.) and installation, testing equipment, etc.
3.1 Microtubes are divided into single microtube and multi-microtube
The single microtube is a tube produced by extrusion, and the outer skin of all single microtubes is flame-retardant, low-smoke, halogen-free material, it will not produce toxic gas when burning, thus meeting the requirements of the latest international standards. The wall of the inner surface of the microtube is a low friction lining, which is very smooth and facilitates the blowing of the core in the tube.
Multimicrotubules are formed by bundling multiple single microtubules straightly through the outer cover, and each multi-microtubule can be composed of 2, 4 or 7 single microtubules.
To meet the needs of different routing configurations and lengths, there are two specifications of single microtubes to choose: 5 mm outer diameter and 3.5 mm inner diameter or 8 mm outer diameter and 6 mm inner diameter. Because the inner diameter of the 8 mm tube is thicker, the blowing distance is also longer.
The minimum bending radius is a very important construction parameter, and it is also an index that can reflect the construction flexibility of air-blown optical fibers. Using a 5 mm diameter microtube, it can be blown to over 300m in the case of a multi-curved route and over 500m in a straight route. With 8 mm microtubes, the blowable distance exceeds 600m in the case of multi-curved routes and over 1000m in straight routes.
3.2 Air blown fiber core
The core of the air-blown fiber is packaged in a shaft, and its surface coating is very thin, it is inconvenient to print any logo, so different colors are used to identify different fibers in the same microtube.
The single-core of air-blown optical fiber is the same as that of ordinary optical fiber. There are three types of multi-mode including 62.5/125μm, 50/125μm, and single-mode, and its performance is no different from that of traditional optical fiber. The surface of the optical fiber is treated with a special coating, and the coating surface has scaly raised irregular fine particles, and the weight is extremely light, 0.23g per core per meter, so the flexibility of blowing is extremely strong. When the compressed air enters the empty tube, the optical fiber is suspended in the empty tube by aerodynamic force and floats forward by the action of air vortex, the fiber core has no directionality during blowing, and the blowing direction only depends on the blowing direction of the compressed air.
3.3 Air blown fiber accessories
Air-blown fiber accessories include air-blown fiber optic connectors, ceramic connectors for microtube connections, termination caps, connector plugs, empty connectors, 482.6mm air-blown fiber optic patch panels, wall and floor-type fiber optic outlet boxes, etc. The accessories of the air-blown fiber optic system and their functions are as follows.
Air-blown fiber system accessories and their functions
|Microtube connector||Embedded in the modular body. For direct connection of 5mm microtubes and fiber accessories.|
|Microtube connector||Connecting microtubes. Compressed air connector packaged in the plastic shell, suitable for connecting microtubes of the same specification.|
|Termination caps||For temporary storage of microtubule fittings indoors.
Connector plug: For indoor long-term storage of micropipette connectors.
|Connector plug||For indoor long-term storage of micropipette connectors.|
|Air containment boxes and conversion splice boxes||Used to convert outdoor polyethylene sheathed multi-microtubules to indoor LSZH sheathed single microtubules or multi-microtubules.|
|Wall outlet||The plug-in module components are integrated in the outlet and are connected to the fiber optic box for terminating optical fibers on the back and storing up to 4 fibers; it can be directly connected to the standard inch (UA2) wall cassette.|
|Ground outlet||Modular elements are used to terminate fibers with fiber optic cassettes and store up to 4 fibers; can be connected to standard ground cassettes.|
|1U patch panel with fox block tray||Standard 482.6 mm, can terminate 24 fibers to ST, SC or FC-PC head, one or two fiber managers can be installed in the tray, both can accommodate 12 fibers for fusion or direct termination.|
|Other accessories include 2.5mm and 4.5mm diameter test steel balls, routing splice boxes, splice boxes, Y-shaped adapters, T-shaped heads, pipe cutters, and fusion splicing protectors, depending on the specific needs of the fiber optic wiring project.|
3.4 Air-blowing fiber machine
The air-blown fiber optic machine consists of two modules: the installation equipment box and the air handler box. The installation module includes a mechanism to guide the fiber into the blowpipe (blow head), and fiber installation control equipment located in another box. The unit can blow up to 8 core fibers into the pre-installed micro-pipe routing and can control the travel speed during the fiber introduction and blowing process, and the compressed air is controlled in real-time by the fiber measurement system and control software. The housing of the drive train is used to store the air conditioning unit.
In 1996, BICC made a lot of improvements on the basis of the original equipment and launched the improved equipment IM2000. The IM2000 consists of two suitcases with a total net weight of less than 35kg, which can be placed in two suitcases for easy portability and installation, and the blowing speed can reach up to 40m/min.
3.5 Air-blown optical fiber test equipment
After the installation of the air-blown optical fiber micropipes and before the fiber is blown, it is necessary to test the laying quality and the quality of the blowing pipes after the blowing pipes are installed.
The micropipe test tool is mainly divided into two parts: the test head and the tail receiver. First, connect the pre-installed air-blown fiber optic empty microtube to the test head and tail receiver respectively, then send a small test steel ball into the empty microtube, send compressed air into the empty microtube through the test head, and then check the tail whether the end receiver can receive the test steel balls. If the steel balls are received smoothly, it means that the air-blown optical fiber air microtube is not blocked, twisted or broken, and there is no major damage. Then close the air pressure valves of the test head and tail end receiver, continue to send compressed air (must use dry and clean air with a dew point higher than -40°C) into the empty microtube, and then observe the air pressure on the air pressure gauge on the test head whether the pointer changes over time. If the pointer does not change within a certain period of time, it means that the pre-installed air-blown fiber air microtube has no loopholes or cracks, and then seals both ends of the exit, which have been air-blown fiber in future use.
4. What is air blown fiber installation?
4.1 Air-blowing laying principle
There are more types of air blowing equipment, the working principle is similar, mainly by the air compressor provides high pressure airflow, so that the fiber optic cable in the pipeline produces floating force, by the air blowing machine hydraulic drive (or air drive ) propulsion device to produce forward propulsion of fiber optic cable, so as to complete the whole process of laying fiber optic cable.
4.2 air-blown fiber optic cable construction steps
The construction steps of fiber optic cable air blowing: routing positioning – manhole (fiber optic cable well) installation – HDPE (high-density PVC pipe or silicon core pipe) pipe laying with plate – silicon core pipe laying –Cleaning silicon core pipe –Pipe airtightness inspection –Testing before laying optical cable –Pipe blowing –Pre-lubrication –Blowing cable –The coiling and fixing of fiber optic cable.
Among them, in the 3 processes of pipe penetration inspection, pipe airtightness inspection and blowing, if pipeline deformation, blockage, breakage, air leakage, poor sealing of joints and other problems are found, they must also be promptly eliminated before proceeding to the next process.
4.3 Method of air blowing optical cable
4.3.1 One-end air blowing method
Advantages: Avoid intermediate openings, and complete the maximum length of the expected air blowing installation at one time.
Disadvantages: If an obstacle is encountered during the air blowing process and the expected maximum length cannot be reached, it is necessary to reopen the operation at the obstacle point, and the silicon core tube at the obstacle must be cut for inspection, operation, and repair after the operation, which will waste the cost of people, machines, material.
4.3.2 Relay air blowing
The relay air blowing method uses multiple air blowers to work together. When the first air blowing machine send the cable to the next air blowing point, the second air blowing machine began to work, the new high-pressure airflow through the second machine into the air chamber to the next pipe, and from the exhaust port released the high-pressure airflow in the upstream pipe.
Advantages: Through such relay air blowing, the optical cable can be air blown for a long distance.
Disadvantages: This method requires a lot of equipment and a large one-time investment. At the same time, due to changes in terrain, it is not easy to accurately determine the position of the air blowing point.
4.3.3 Air blow from the middle to both ends
When the laying length exceeds the one-time air blowing length of one air blowing machine, you can choose to blow from the middle opening of the line to both ends, and the one-time air blowing length is about half of the total length. First, install the rewinder near the cable reel. When one end of the micro-cable is laid, pour the remaining micro-cables on the cable reel into the reel with an air blower, take out the end of the micro-cable in the inner ring, and then blow the air to the reel. Reverse the direction and blow the micro cable from the rewinder into the pipe. If there is no problem with the laying of the pipeline, the success of one air blow is more certain.
4.3.4 Leap-frog air blowing
The leapfrog air blowing is similar to the relay air blowing method, but instead of the air blower but the disc reverser installed at the next blowing point, the high-speed airflow in the pipe is used to collect all the optical cables from the upstream air blowing point to the next air blowing point. Then transfer the blower to the next blowing point.
Advantages: The laying of long-distance optical cables can also be completed with an air blower.
Disadvantages: The workload of the reverse disk is large and the efficiency is low. The actual air blowing length of an air blower will be much larger than the actual line length.
5. Comparison between ABF and conventional fiber cables
We will compare them in terms of cost, value and installation, etc. between ABF and conventional fiber cables.
5.1 Simple design
In the traditional optical fiber cabling design, due to the consideration of fiber cost (including termination, splicing) and the difficulty of deployment, it is impossible to fully consider the future needs and make the wiring as comprehensive as possible. The air-blown optical fiber system is different. When designing, it is only necessary to consider the physical structure of the optical fiber system, lay the air-blown optical fiber microtubes as much as possible, and then blow the optical fiber into it for termination according to actual needs.
Comparison of conventional fiber optic cabling system and air-blown fiber optic cabling system
|Item||Conventional fiber optic cabling system||Air-blown fiber optic cabling system|
|Design||Consider fiber costs and deployment difficulties in advance||No need to consider cost, according to the physical structure of the fiber system|
|Microtubule installation||Direct laying of fiber optic cables||Micropipes need to be installed|
|Layout||Flexible, convenient and labor-saving (especially suitable for the situation where the route is more curved)||Inconvenient and labor-intensive (especially when the route has many bends, it requires a lot of labor)|
|Floor patch panel jumper||Requires a jumper||No jumpers required, connect directly to the desktop|
|Adaptation||Desktops for communication backbone and special needs||Fiber to every work desktop|
|Future network expansion||Inconvenient||Convenience|
|Modify and fix routes||Difficulty||Easy|
|Diversification||One-time laying of optical fibers requires large redundant funds and cannot be invested in stages||In the initial stage, it is only necessary to install empty micropipes to build the routing of the entire optical fiber cabling system, and then blow into the optical fiber when needed, which is a phased investment method.|
|Save on investment||The phenomenon of idle fiber waste is serious and the investment is huge.||High fiber utilization rate, saving investment cost.|
5.2 Routing can be modified and repaired arbitrarily and flexibly
In the construction of conventional optical fiber cabling system, if the optical fiber link fails, whether it is the damage of the optical cable or the termination problem, it is not easy to repair. When the air-blown optical fiber system finds the micropipe failure, it only needs to cut off the faulty section of the micropipe, and use two special pipe joints and a good section of the micropipe to splice the micropipe route. The cost of air-blown optical fiber system to solve the failure in optical fiber construction only accounts for about 10%~30% of conventional optical fiber.
5.3 Greatly diversify the investment cost of users
At present, due to the consideration of the cost of the optical fiber system, the solution that requires optical fiber is rarely adopted at the beginning, and when the optical fiber needs to be added later, it is helpless because there is no suitable laying route. In the initial stage of the air-blown optical fiber cabling system project, only empty air-blown optical fiber air micropipes need to be installed. Since the price of empty micropipes is very low (only accounts for about 5% of the entire optical fiber cabling system), it means that users only need to spend 5% %-10% cost of the budget in the initial stage can build the routing of the entire fiber optic cabling system (saving and protecting 95% of the user’s initial investment). When the fiber application is required, the fiber is purchased, and the fiber is blown into the pre-installed empty microtube by compressed air. For users, this is a way to invest in installments.
5.4 Convenient fiber cabling expansion and upgrade
After more than a third of fiber optic systems in Europe were installed, they faced the need for an upgrade within the first six months, with a quarter of fiber optic systems to be upgraded within the following eighteen months. If the conventional optical fiber system is used, when upgrading, the old optical fiber system must be discarded first, and then the optical fiber installation is carried out again. The loss of manpower, material resources and financial resources such as downtime, system paralysis, office, decoration, etc. will be lost. It’s huge and immeasurable. With air-blown fiber system, it’s much simpler. Another feature of the air-blown fiber is that it can be blown in and out. When the type of optical fiber needs to be replaced in the future network upgrade, there is no need to re-construct. The pre-laid air-blown optical fiber microtube can be used to blow out the original old optical fiber, and then blow in the new optical fiber of the required type, so as to fully meet the user’s expectations for the future demand.
5.5 Save investment
According to the statistics of the American FIA Association, 72% of users have idle waste after optical fiber installation. After adopting the air-blown optical fiber system, in the early stage of the building, only the air-blown optical fiber micropipes, accessories and part of the optical fibers need to be laid out. As users move in continuously, the optical fibers can be blown in as needed, which saves a lot of investment.
To sum up, the air-blown optical fiber system, as a new wiring method, can be used for any application that can be realized by traditional optical fibers, regardless of the type of optical fiber, application environment, or network requirements, and air-blown optical fiber wiring. The system is cheap, flexible, convenient and reliable, and can provide users with a safe and cost-effective wiring system, which is bound to promote the rapid popularization of optical fiber networks.