We often talk about the concept of optical cables, but in fact many friends do not know much about the detailed knowledge of optical cables. For example, what are duct optical cables and direct buried optical cables, or what are the differences between duct optical cables and direct buried optical cables? Let's go and find out.
Duct optical cable:
Duct optical cable is an outdoor optical cable used in access network or user premises network. A type of communication optical cable laying method. Duct laying is generally in urban areas, and the environment for duct laying is relatively good, so there are no special requirements for the sheath of optical cables and no armor is required. Before laying the duct, the length of the laying section and the location of the connection point must be selected.
Mechanical bypass or manual traction can be used during laying. The pulling force at one time should not exceed the allowable tension of the optical cable. The materials for making ducts can be concrete, asbestos cement, steel ducts, plastic ducts, etc. according to geography.
Direct buried optical cable:
Direct buried optical cable is a communication optical cable laying method. This kind of optical cable is armored with steel strips or steel wires on the outside and is directly buried underground. It is required to resist external mechanical damage and prevent soil corrosion.
What is the difference between duct optical cable and direct buried optical cable?
The following preparations should be made before laying duct optical cables
1) Check the position of the tube hole occupied by the optical cable according to the design;
2) The hole position selected on the same route should not be changed. If it is changed or turned, the bending radius requirements of the optical cable should be met;
When laying optical cables manually, each manhole should be manned; when laying optical cables mechanically, manholes at the corners should be manned.
When the optical cable penetrates the duct hole or the duct turns or crosses, a guide device or a bell mouth protective tube should be used to avoid damaging the outer sheath of the optical cable. Apply neutral lubricant around the fiber optic cable as needed.
The length of a single pull of an optical cable is generally no more than 1,000 meters. When the length is too long, figure-8 segmented traction or auxiliary traction in the middle should be used.
After the optical cable is laid, a dedicated person should be under unified command to place the optical cable on the specified pallet one by one, and an appropriate margin should be left to prevent the optical cable from being too tight.
The reserved length of the optical cable in the manhole where the connector is located should comply with the requirements in the table; the optical cable that requires special reservation in the design is too tight.
Protection measures for duct optical cables should meet the following requirements:
1) Optical cables in manholes can be protected by snake-shaped hoses (or soft plastic tubes) and tied to cable pallets or handled according to design requirements;
2) The duct mouth should be blocked;
3) Optical cables in manholes should have identification marks;
4) In severely cold areas, antifreeze measures should be taken according to design requirements to prevent damage to optical cables.
The laying method of plastic sub-ducts is basically the same as that of optical cables, and should also meet the following requirements:
1) When laying out two or more sub-ducts without color markings, marks should be made at the ends;
2) The ambient temperature where plastic sub-ducts are laid should be between -5oC--+35oC;
3) The length of continuously laid plastic sub-ducts should not exceed 300 meters;
4) The maximum pulling force of the pulling sub-duct should not exceed the tensile strength of the duct, and the pulling speed must be uniform;
5) The remaining length of the sub-duct in the manhole should meet the design requirements;
6) A plastic duct plug should be installed in the hole where the plastic sub-duct is placed (other methods can also be used) to fix the sub-duct;
7) The sub-duct must not have joints in the middle of the duct;
8) After the sub-ducts are laid out, the duct mouths should be temporarily blocked; sub-ducts not used in this phase of the project must be installed with plugs (caps) on the duct ends.
The distance between directly buried optical cables and other buildings and underground ducts should meet the specified requirements.
Optical cables laid in the same trench must not cross or overlap. They should be pulled separately and laid out simultaneously.
The laying of direct buried optical cables should meet the following requirements:
1) The depth of the optical cable trench should comply with the regulations, and the bottom of the trench should be smooth and free of gravel; the bottom of the stony or semi-stony trench should be paved with 10 cm of fine soil or sand;
2) When mechanical traction, ground pulleys should be used;
3) When manually lifting, the optical cable should not be bent less than the specified radius of curvature, dragged on the floor, or pulled too tightly, etc.;
4) The optical cable must be placed flat at the bottom of the trench and must not be vacated or arched;
5) When laying optical cables on slopes with a slope greater than 20° and a slope length greater than 30 meters, it should be laid in an "S" shape or handled according to design requirements;
6) During or after the laying process, the outer sheath of the optical cable should be checked in time. If it is damaged, it should be repaired immediately; after the laying of the directly buried optical cable, the insulation resistance of the optical cable sheath to the ground should be checked.
7) The optical fibers and copper conductors in the optical cable must be inspected and confirmed to meet the quality acceptance standards before they can be fully trenched and returned to the soil.
Optical cable trench backfill soil should meet the following requirements:
1) Backfill 15cm thick broken soil or fine soil first. It is strictly forbidden to push stones, bricks, frozen soil, etc. into the trench, and it should be leveled manually;
2) The backfill soil should be 10 cm above the ground.
The above is all about what are duct optical cables and direct buried optical cables and what are the differences between duct optical cables and direct buried optical cables. I believe that after reading this article, you will have a certain understanding of duct optical cables and direct buried optical cables. I hope it can help you.