The Difference Between Loose Tube Fiber and Tight Buffer Fiber

Tight-buffered cables oftenn are used for intra-building, risers, general building and plenum applications. Tight buffer fiber contains a thick coating of a plastic-type material which is applied directly to the outside of each individual fiber. Loose tube fiber optic cable is typically used for outside-plant installation in aerial, duct and direct-buried applications. Loose tube fiber contains multiple strands of fiber in a single jacket. Since the fibers are “loose” inside the jacket, outside forces are less likely to reach the fibers. This makes it the more durable option of the two.

Loose Tube Cable

Loose-tube fiber generally consists of 12 strand of fiber, but can range anywher as low as 6, all the way up to 244 strands. Loose tube cables can be either dielectric or optionally armored. The modular buffer-tube design permits easy drop-off groups of fibers at intermediate points, without interfering with other protected buffer tubes being routed to other locations. The loose tube design also helps in the identification and administration of fibers in the system.

In a loose tube cable design, color-coded plastic buffer tubes house and protect optical fibers. An optional gel filling compound impedes water penetration. Excess fiber length (relative to buffer tube length) insulates fibers from stresses of installation and environmental loading. Buffer tubes are stranded around a dielectric or steel central member, which serves as an anti-buckling element.

The cable core, typically uses aramid yarn, as the primary tensile strength member. The outer polyethylene jacket is extruded over the core. If armoring is required, a corrugated steel tape is formed around a single jacketed cable with an additional jacket extruded over the armor.

Tight-Buffered Cable

Single fiber tight buffered cables are used as pigtails, optical patch cord or fiber jumpers to terminate loose tube cables directly into opto-electronic transmitters, receivers and other active and passive components. Multi fiber tight buffered cables also are available and are used primarily for alternative routing and handling flexibility and ease within buildings. With tight buffered cable designs, the buffering material is in direct contact with the fiber. This design is suited for “jumper cables” which connect outside plant cables to terminal equipment, and also for linking various devices in a premises network.

The tight-buffered design provides a rugged cable structure to protect individual fibers during handling, routing and connectorization. Yarn strength members keep the tensile load away from the fiber.

As with loose-tube cables, optical specifications for tight-buffered cables also should include the maximum performance of all fibers over the operating temperature range and life of the cable. Averages should not be acceptable.

How To Distinguish Between Good or Bad The Quality of Fiber Optic Cable

1. Ointment. Ointment is mainly fine paste paste with cable, fiber paste normally should be full of the casing, cable paste should be under pressure every crevice of cable core. Now, fiber paste sufficient half-full or less the practice of cable extract some just wipe a layer of the cable core, while others are in the middle of the fiber optic cable two charge is not sufficient. This will make the fiber are not good protection, the impact of the transmission performance of optical fiber attenuation, poor water resistance less than the national standard, once the cable accidental seepage will cause the whole links seepage scrapped. Under normal circumstances, even accidental seepage simply repair a section of water seepage can, you do not need to start over. (National standard water-blocking performance: three meters of fiber optic cable, one meter of water column pressure round the clock impermeable.) If use poor ointment will also appear to be happening, and may because the ointment thixotropic, cause the fiber to cause microbending loss, the link transmission characteristics failed; ointment with acidic also with fiber optic cable metal materials analysis H reaction precipitation of hydrogen molecules, fiber case of H decay will increase dramatically, resulting in the entire link interrupt transmission.

2. Sheath. The cable sheath is necessary to adapt to many different complex climate, but also to ensure the stability of the long-term (at least 25 years). Cable jacket not only have a certain strength, low thermal deformation, wear, water permeability, heat-recoverable, and coefficient of friction, but also should be strong resistance to environmental performance materials processing features. Less or bad sheath material cracking, water seepage through factory acceptance, but the quality is defective use for some time, using recycled plastics to replace quality polyethylene sheath material is more serious. High quality sheath material made of fibe optic cable, a cable skin smooth, bright, uniform thickness, no bubbles, otherwise the coarse skin of fiber optic cable, and a lot of very small pit, and because of the thin thickness, the entire outer diameter of the fiber optic cable will be muach smaller than the high quality cable. Indoor fiber optic cable, usually made of high quality flame retardant PVC, the appearance should be smooth, bright, good flexibility, easy to peel; and otherwise poor skin finish, easy and tight buffer fiber, aramid adhesion phenomenon.

3. Steel, aluminum. Steel, aluminum cable is mainly used to protect the fiber from mechanical side pressure, moisture and other effects, better cable typically use chrome-plated steel strip. Low quality fiber optic cable to only one side done ordinary iron rust treatment, or black (uncoated steel), instead of chrome-plated steel strip, over time, the cable will appear corroded, fiber optic hydrogen loss also aggravate andits easy separation do not constitute the sheath bonded sheath tide also very poor performance; of some places tinned strip instead of chrome-plated steel strip, tin-plated surface of the strip, the bubble is inevitable, so in humid, prone to corrosion under the conditions of the atmosphere and surface condensation or water, especially under acidic conditions, corrosion faster. The tin plating layer is poor in heat resistance, melting at 232 degrees Celsius, only the application of due to squeeze sheaths when the high temperature, such that the peel strength uncertainty affect the cable anti-surge performance. Chromium melting point of 1900 degrees Celsius, chemically very stable at room temperature in air or water will not rust, corrosion resistance, very good resistance to environmental performance, easily oxidized due to surface passivation layer is formed so good. Aluminum generally failed thermal paste method coated aluminum instead of cast qualified coated aluminum, which also affect cable performance.

4. Steel wire. The steel wire in the fiber optic cable mainly used to protect optical fiber from the mechanical tension. Good cable typically use for phosphating steel wire, high modulus short-term tension 1500N and 3000N. And low-quality fiber optic cable will be a very small diameter wire or ordinary steel instead of the one hand, easy to rust; On the other hand, is far less than the tensile strength 1500N construction may strain the fiber. High modulus phosphide stell wire is generally gray color, good toughness, not easy to bend; the alternative wire generally pinch in your hand can be bent a long time, the two rust fracture hanging cable box.

5. Loose tube. The installed fiber loose tube fiber optic cable is generally used polymer PBT material (poly (butylene terephthalate)), this loose tube, high strength, no deformation, anti-aging. Poor quality loose tube fiber optic cable is sometimes replaced with other materials, diameter thin, hand pinch flat, no different from drinking straw, can not afford the protective effect of the fiber.

6. Waterproof tape. Fiber optic cable with waterproof tape or water blocking yarn through the inside of the product showed a uniform distribution of high water-absorbing resin has strong water absorption, under the combined effect of the osmotic pressure, affinity, rubber elastic, super absorbent resin inhalation several times the weight of water. Further, the water-blocking powder once with water swollen gel will instantly, regardless to its much pressure is applied, moisture nor is extruded. Thus, with a water-absorbent resin containing water-blocking tape coated cable core, in case the outer wall of the fiber optic cable is damaged, the wound portion of the high water-absorbent resin to play due to expansion of the sealing effect, can prevent the entry of water to a minimum. Low-quality fiber optic cable commonly used non-woven fabric or paper tape, once the cable jacket is damaged, the consequences will be very serious.

7. Kevlar. Kevlar is a high-strength chemical fiber, most in the field of military-industrial complex, a bullet-proof vest is the producer of this material. It is a patented product of DuPont, is the major cost components of the indoor fiber optic cable, tight buffer fiber indoor cable is mainly used to protect against mechanical tension. Due to Kevlar high cost, poor quality of indoor fiber optic cable outer diameter is generally made ​​very thin, so you can by reducing the few shares aramid cost savings, or use an appearance similar to Kevlar polyester yarn instead (more common) polyester yarn almost can not bear what tension. So that the optical fiber laying easily strain or pull off.

8. Optical fiber. The fiber optic cable core raw materials, the good cable commonly used manufacturers of high quality core. Low-quality fiber optic cable is usually lower fiber and unsolicited fiber, these fibers due to the complex sources, quality is difficult to guarantee, sometimes multimode fiber often mixed with single-mode fiber, and the general lack of small factories necessary testing equipment, not fiberquality of judgment, more so the quality is difficult to be guaranteed. In addition, some bought with cheap short segment later cabled fiber splicing. The naked eye can not distinguish this fiber, the problems often encountered in the construction are: low transmission rate, short distance, fiber attenuation, not and pigtail docking, lack of flexibility, easily broken plate filament when even a single fiber a multi-mode, the other end is single-mode.

9. Coloring ink. Distinguish fiber in order to facilitate the construction of national standards be with bright color and high-quality fiber optic cable are standard in high quality ink colored fiber loose tube, the color is very clear and easy to fall off, while the low quality fiber optic cable is used poor qualityink coloring or simply coloring and inferior ink colors are vivid and sometimes easy to dissolve in the fiber paste the color can not be distinguished, not colored even more great inconvenience to the construction.

10. Product packaging. The fiber optic cable commonly used packaging wooden plate or the iron wooden tray into the shaft, the outside of the plate sealed wooden seal plate to ensure that the bulky fiber optic cable throughout the transit force, bending radius conditions within the scope of the standard requirements. Low-quality fiber optic cable in order to save costs, generally very poor packaging tray, transported to the destination is almost close to falling apart, and some simply do not have the disk, look around cable is shipped, or the disc do not have to seal the wood.

In summary, optical fiber cable real good or bad from the structural design, integrated the difference between the pros and cons of the timber material and production process. Because the cable is not yet a large number of popular, low-quality products, while a lot of hidden dangers, many users even integrators do not understand the line is still used regardless of settings.

It is for this reason that the negative impact of low-quality fiber optic cable industry will be even greater, because the fiber optic cable itself, its value is not significant, but the cost of laying process (direct burial, aerial, wearing a tube) were truly amazing.and time-consuming, coupled with its entire communication link based medium, so if there are problems, no matter how expensive your hardware devices at both ends of the high-end, the entire system will be, without exception, completely paralyzed, will be a very long period of repair, resulting in the loss of thousands of times the difference between the pros and cons.

If you want to know more about breakout fiber cable, hybrid cable or fiber optic cable cost, please visit our website.

Understand Variety of Fiber Optic Cables and Components Basic Knowledge

1. FTTH fiber cable

FTTH (Fiber To The Home), by definition is an optical fiber directly to the home. Specifically, FTTH refers to the optical network unit (ONU) installed in the home user or business user, in addition to the optical access family FTTD (fiber to the desktop) closest to the users outside the optical access network application type.

There are five main advantages of FTTH:

. It is passive network, from the central office to the user, the intermediate can be done basically passive;

. Its bandwidth is relatively wide, long-distance carriers fits the way large-scale application;

. Because it is hosted on the fiber business, and there is no problem;

. Because of its relatively wide bandwidth, support for the agreement is more flexible;

. As technology advances, including point to point, 1.25G and FTTH way have developed a relatively complete function.

2. Indoor fiber cable

Indoor optical fiber cables are classified according to cable using the environment, as opposed to a outdoor fiber optic cable.

Indoor cable is made up of optical fiber (optical transmission medium) through a certain process and the formation of the cable. It is Mainly composed of optical fiber glass(glass as thin as a hair) and plastic protective sleeve and plastic sheath structure, fiber optic cable is not gold, silver, copper and aluminum and other metals usually no recovery value.

Indoor fiber optic cable is a certain amount of composition according to certain way cable heart, outsourcing jacket, and some also cover the outer sheath for optical signal transmission to achieve a communication line.

The tensile strength of the small indoor fiber optic cable, a protective layer is poor, but also more lightweight and economical. Indoor cable mainly used in building wiring, and connections
between network devices.

3. Outdoor fiber optic cable

Outdoor fiber optic cable, used for outdoor optical cable. As opposed to a indoor optical fiber cable.

Outdoor cable is one of the optical transmission line. Consists of a certain number of optical fiber according to certain way cable, outsourcing has a sheath, some still coated outer sheath.

Outdoor fiber optic cable consists of an optical fiber glass (glass as thin as a hair) and plastic to protect casing and plastic coating, fiber optic cable is no gold, silver, copper, aluminum and other metal, there is no recycling value.

Outdoor fiber optic cable tensile strength greater than the thick protective layer, and is usually sheathed (i.e metal leather wrapped). Outdoor cables is mainly applied to buildings, and between the interconnection between remote networks.

4. Fiber Optic Patch Cord

Fiber optic patch cord used to make the link from the device to the jumper cables fiber optic cabling. Fiber jumper has a thicker layer of protection, commonly used in the connection between the optical and terminal box. The commonly used fiber optic jumper include: ST, LC, FC, SC type.

Main categories:

Single-mode fiber jumper (Single-mode Fiber): Average single-mode fiber jumper with yellow connector and protective sleeve blue; transmission distance is longer.

Multimode fiber jumper (Multi-modeFiber): General multimode fiber jumper in orange, and some in gray, fittings and protection applied beige or black; transmission distance is shorter.

5. Optical Fiber Coupler

Fiber coupler also known as fiber adapter, fiber coupler for connecting fiber optic connectors, couplers. According to fiber optic connector head selection models. According to the connection head structure can be divided into: FC, SC, ST, LC, MTRJ, MPO, MU, SMA, DDI, DIN4, D4, E2000 various froms.

6. Optical fiber terminal box

Optical cable terminal box (also known as fiber optic terminal box or cable box) is a small core fiber optic cable to connect with the terminal equipment, mainly used for cable ends fixed, cable and fiber pigtail splice and I containment and protection.

7. Fiber Fusion Splicer

Two fiber optic cable connection, fiber optic cable should butt up inside the fiber because fiber is like glass, must be refused on the two dedicated connectors, connector card and then put together, so that the optical signal can be passed.

Light in the optical fiber transmission loss can be created, the loss is mainly consist of optical fiber transmission loss and loss of fiber of welding joint. Fiber cable once order, the basic purpose of optical fiber transmission loss but also determined that the loss of fiber of welding joint is related to fiber itself and site construction. Efforts to reduce the loss of fiber of welding joint, can increase the fiber optic repeater amplification and transmission distance attenuation of optical fiber link margin.

If you would like to purchase these items or want to know more about fibre optic cable specification, optical cable price or loose tube fiber optic cable, please visit our website.

What is Loose Tube Fiber Optic Cable

Loose tube cable: small, thin plastic tubes containing as many as a dozen 250 micron buffered fibers used to protect fibers in cables rated for outside plant use. They allow the fibers to be isolated from high pulling tension and can be filled with water-blocking materials to prevent moisture entry.

Loose tube cables are the most widely used cables for outside plant trunks because it offers the best protection for the fibers under high pulling tensions and can be easily protected from moisture with water-blocking gel or tapes.These cables are composed of several fibers together inside a small plastic tube, which are in turn wound around a central strength member, surrounded by aramid strength members and jacketed, providing a small, high fiber count cable. This type of cable is ideal for outside plant trunking applications, as it can be made with the loose tubes filled with gel or water absorbent powder to prevent harm to the fibers from water. It can be used in conduits, strung overhead or buried directly into the ground. Some outdoor cables may have double jackets with a metallic armor between them to protect from chewing by rodents or kevlar for strength to allow pulling by the jackets. Since the fibers have only a thin buffer coating, they must be carefully handled and protected to prevent damage. Loose tube cables with singlemode fibers are generally terminated by spicing pigtails onto the fibers and protecting them in a splice closure. Multimode loose tube cables can be terminated directly by installing a breakout kit, also called a furcation or fan-out kit, which sleeves each fiber for protection.

Loose tube materials for loose tube cables need to possess a relatively high modulus and good processability. During manufacture, optical fiber is fed into the loose tube at a faster rate than it is being produced so that the optical fiber is laid helically within the tube.

To buffer the fibers from each other and from any perturbations on the tube walls, the loose tube is filled with a gel compound similar in composition to the water blocking gels in conventional telecommunication cables. The loose tube material must therefore be compatible with the gel as in conventional cable insulation.

Structure of a Loose Tube Fiber Optic Cable

Elements in a loose tube fiber optic cable:

1. Multiple 250um coated bare fibers (in loose tube)
2. One or more loose tubes holding 250um bare fibers. Loose tubes strand around the central strength member.
3. Moisture blocking gel in each loose tube for water blocking and protection of 250um fibers
4. Central strength member (in the center of the cable and is stranded around by loose tubes)
5. Aramid Yarn as strength member
6. Ripcord (for easy removal of outer jacket)
7. Outer jacket (Polyethylene is most common for outdoor cables because of its moisture resistant, abrasion resistant and stable over wide temperature range characteristics.)


. Good mechanical and temperature performance
. High strength loose tube that is hydrolysis resistant
. Special tube filling compound ensure a critical protection of fiber
. Two parallel steel wires ensure tensile strength
. PE sheath protects cable from ultraviolet radiation
. Small diameter, light weight and friendly installation
. Long delivery length

More information about fiber optic cable cost, fibre optic cable specification please visit our website.

The Advantages of Loose Tube Cables In Outdoor Applications

Optical cables are designed to protect the optical fibers from damage due to the rigors of installation and from the demands of the surrounding environment. No single optical cable design is
universally superior in all applications, however. In order to meet application – specific requirements, outside plant (outdoor), indoor outdoor cables, and inside plant (indoor) cables must be designed for their intended installation environment. The consequences of optimizing a cable design for outdoor use can prove counterproductive to meeting the requirements for indoor placement and vice versa. For example, the most popular cable jacket material for outdoor use will not pass flame resistance tests required for placement indoors. In general, optical fiber cables installed in an outdoor environment are exposed to more severe mechanical and environmental conditions than are experienced in the protected, climate-controlled, indoor environment. Outdoor installations (usually lashed aerially, pulled through duct, or directly buried in the ground), are subjected to combinations of ultraviolet (UV) radiation, standing water, cable-gnawing rodents, temperature extremes and other outdoor-specific hazards. Loose tube optical cable designs are optimized for outside plant applications and have demonstrated over 20 years of proven field performance.

Performance at Extreme Temperatures

The major constituents of an optical cable structures are silica glass and polymeric plastics. For a given temperature change, the rate/magnitude of material expansion and contraction will be different because each material possesses a different coefficient of thermal expansion. The loose tube cable establishes a strain-free environment for the optical fiber by mitigating the influences of this effect. Loose tube cable manufacturing processes ensure that the optical fiber to buffer tube length ratio is controlled such that no optical fiber is compressed against the tube wall when the tube expands or contracts with changes in temperature. The strain-free environment established in the loose tube cable design compensates for movement in the cable structure without inducing mechanical forces on the fiber. This characteristic enhances the operating temperature range of the loose tube design.

Protection from Ice Crush Effects (Waterblocking requirement)

Ice crush hazards affect optical cables in locations where standing water and freezing temperatures coexist. In a confined space, significant tensile and compressive forces can be generated from the expansion of water as it transitions to a solid state under cold conditions. In optical fiber cable applications, this effect can occur in water-filled outdoor conduits or within the cable core itself. Water migration inside the cable’s outer jacket can result in the formation of ice crystals within the optical fiber cable core. This ice will impart stresses in close proximity to the optical fibers and may result in an unacceptable increase in attenuation or even fiber breakage. Therefore, it is essential to prevent the intrusion and uncontrolled movement of water inside the cable.

loose tube fiber optic cable is designed to provide maximum protection against water penetration and water migration by utilizing intrusion preventative measures in both the cable core and the buffer tubes. Water-blocking protection of the cable core is accomplished by surrounding it with a dry water-swellable tape and yarns, or with a gel, to stop the entry and migration of water should the cable’s outer jacket be breached. This protective measure is included primarily to maintain the mechanical integrity of the cable itself (e.g. prevent ice crush from within the cable, fungus growth, or corrosion of metallic cable members when present). The water-blocking protection, water-swellable yarn or gel, is placed in the buffer tubes with the optical fiber during manufacture of the cable.

Mechanical Protection

As stated previously, loose tube cable establishes a strain-free environment for the optical fiber by mitigating the influences of external effects. In addition to the benefit provided at extreme temperatures, this attribute also enhances the performance of the loose tube cable design under a variety of mechanical forces. Installation practices and installed system conditions can subject the cable to tensile, flexure, twisting, crush, impact and bending forces. By isolating the fiber from these external forces, the loose tube design ensures maximum cable life in an outdoor environment.

UV Protection

The optical fiber cable must also be able to withstand direct exposure to ultraviolet sunlight in aerial installations. In the outdoor environment, light, heat and moisture combine to cause optical, mechanical and chemical changes in materials and the first line of protection of any optical fiber cable is the cable outer jacket. Carbon black, which is compounded into the jacket material to provide maximum ultraviolet protection, is the best defense against ultraviolet degradation.


The predominant users of outside plant cable continue to specify loose tube cables in outdoor environments. Loose tube cables must pass rigorous mechanical, environmental and optical
tests in accordance with accepted Electronic Industries Association/Telecommunications Industry Association (EIA/TIA) fiber optic test procedures (FOTPs). Loose tube cables are specifically designed to perform in harsh outdoor environments with minimal performance degradation.

A new standard, ICEA S-104-696, “Standard for Indoor – Outdoor Optical Fiber Cables” has been developed which addresses the need for an interbuilding and intrabuilding cable. These cables can be loose tube or tight buffered for the ease of termination such as premises cable, but must offer the tensile strength, waterblocking protection, and UV protection of an outside plant cable. These inter-/intrabuilding cables are typically used for short runs to connect to another building(s) and some limited premises applications.