Basic but Important Information about Loose Tube Fiber Optic Cable

loose tube cable

There are two main types of fiber optic cable construction: loose tube and tight buffer cable. Loose tube fiber optic cables are ideal for outdoor environments where extreme environmental conditions play a major role in cable selection. This article will introduce basic but important information about loose tube fiber optic cable.

Click to learn more about the differences between loose tube and tight buffered optical cable.

What is the function of the buffer tube in the optical cable?

Before learning about loose tube fiber optic cable, we quickly get through the function of the buffer tube in the optical cable.

Buffer tubes are used in fiber optic cables to protect fibers from signal interference and environmental factors, as they are commonly used in outdoor applications. Buffer tubes also block water, which is especially important for 5G applications because they are used outdoors and are often exposed to rain and snow. If water gets into the cable and freezes, it can expand inside the cable and damage the fiber.

What is Loose Tube Fiber Optic Cable?
Loose tube fiber optic cables are designed for harsh outdoor environments. Fiber optic cables protect the fiber core, cladding, and coating by enclosing everything in a semi-rigid protective sleeve or tube. In loose-tube cables containing multiple optical fibers, each individual ferrule core is loosely bundled within an all-encompassing outer jacket. Additionally, many loose tube cables have waterproofing gel around the fibers. This gel helps keep the fiber from getting wet, making the cable ideal for harsh, high-humidity environments where water or condensation may be an issue. The gel-filled tubes can also expand and contract with changes in temperature.
In a loose tube configuration, the fiber is laid as a semi-rigid tube that allows the cable to stretch without stretching the fiber itself, which protects the fiber from tension during laying and temperature changes. Loose tube fibers can be dry-block or gel-filled. Dry blocks offer less fiber protection than gel fill, but are much less expensive.
loose tube typeBetween 1 and 12 optical fibers are placed in individual waterproof buffer tubes to insulate them from external forces and are usually twisted around a fiberglass central strength member for extra strength and resistance. Loose tube cables typically contain up to 432 fibers in total within these tubes.


Features and Benefits
Loose tube fiber optic cables provide stable and highly reliable optical transmission characteristics over a wide temperature range. In addition, the loose tube fiber optic cable provides better protection for the fiber under tension. It is extremely temperature resistant, has UV protection, and protects the fiber from moisture with waterproof tape. Loose tube fiber optic cable is small in diameter, light in weight and easy to install.

Loose tube fiber optic cables are commonly used in overhead, duct and direct burial applications, local area networks (LANs), metropolitan area networks (MANs), wide area networks (WANs), outdoor installations in long-haul and broadband networks, telecommunications, campus backbones, data centers, CATV, broadcasting, computer network system, user network system, 10, 40, 100Gbps Ethernet, etc.

Loose Tube Fiber Optic Cable Products
Outdoor optical cables are basically loose tube optical cables. According to different structures, loose tube fiber optic cable can be divided central loose tube cable, multi loose tube cable and stranded loose tube cable. Here comes some common ones as follows for reference.

Stranded Loose Tube Fiber Optic Cable GYTA

  • The high-strength loose tube that is hydrolysis resistant
  • Special tube filling compounds ensure a critical protection of fiber
  • Special designed compact structure is good at preventing the loose tube from shrinking
  • Good mechanical and temperature performance
  • Crush resistance and flexibility
  • PE sheath protects the cable from ultraviolet radiation
  • Steel wire used as the central strength member
  • Loose tube filling compound
  • 100% cable core filling
  • PSP enhancing moisture-proof

GYTA armored fiber cable

Central Loose Tube Fiber Optic Cable GYXTW

  • Good mechanical and temperature performance
  • High strength loose tube that is hydrolysis resistant
  • Special tube filling compound ensures a critical protection of fiber
  • Crush resistance and flexibility
  • PSP enhancing moisture-proof
  • Two parallel steel wires ensure tensile strength
  • Small diameter, lightweight and friendly installation
  • Long delivery length

GYXTW Armoured Fibre Optic Cable Unitube Duct Cable

Multi-tube Loose Tube Fiber Optic Cable GYFTY

  • Special tube filling compounds ensure the critical protection of fiber
  • Whole section water blocking structure ensures good water-blocking performance
  • The central strength member adopts FRP rod with high modulus
  • Polyethylene sheath makes fiber optic cable have good UV resistance
  • All dielectric nonmetallic materials make optical cables suitable for strong electromagnetic regions and multiple lightning areas

GYFTY Fiber Optic Duct Cable Stranded Non Metallic Strength Member Cable

Loose tube fiber optics provide stable performance over a wide temperature range. In addition, loose tube fiber optic cables provide the best protection for the fiber optics under high tension and can be easily protected from moisture with waterproof gel or tape.

Echo Huang

Echo Huang is an expert wordsmith and marketing professional at Bonelinks with more than 8 years of experience in high technology businesses – fiber optics, IoT, and telecommunication. She is very glad to share industry knowledge and communicate with others.

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