Non-Metallic Duct Direct BuriedFiber Optic Cable

1. Scope
This technical specification states the structure, mechanical, physical performance, and optical fiber requirements for telecommunication use.

2. Standard
Unless otherwise specified in this specification, all requirements shall be mainly in accordance with the following standard specifications.

• International Telecommunications Union (ITU-T)
  G.650   Definition and Test Methods for the Relevant Parameters of Single-Mode Fibers
  G.652   Characteristics of a Zero Dispersion Non- Shifted Single-Mode Optical Fiber Cable
  G.655   Characteristics of a Non-Zero Dispersion Shifted Single-Mode Optical Fiber Cable

• International Electrotechnical Commission
  IEC 60794-1-1 Optical Fiber Cables, Part 1, Generic Specifications-General
  IEC 60794-1-2 Optical Fiber Cables, Part 2, Generic Specifications-Basic optical cable test                           procedures

3. Optical Fiber

3.1 General of optical fibers 
Unless otherwise specified in this specification, all requirements for optical fiber shall be mainly
in accordance with ITU-T G.652 D standards.
The optical fiber core, with a higher refractive index compared to the cladding, is made of SiO2
(Silicon dioxide) doped with GeO2 (Germanium dioxide).The cladding of the optical fiber is made
of SiO2. The primary coating is made of an UV-curable acrylate. This make-up protects the 
fiber against micro-bending losses and against abrasion.

3.2 Technical parameter of ITU-T G.652 (B1. 3) single-mode optical fiber 

Characteristics	Conditions	Specified Values	Units
Optical Characteristics
Mode field diameter (MFD)	1310nm 1550nm	9.2±0.4 10.4±0.8	µm µm
Cut-off wavelength (λcc)		≤1260	nm
Attenuation coefficient	1310nm 1383nm 1550nm	≤0.35 ≤0.34 ≤0.22	dB/km dB/km dB/km
Macro bending loss	Ф75mm, 100 circles, at 1550nm	≤0. 05	dB
Attenuation non-uniformity		≤0.05	dB
Dispersion coefficient	1288～1339nm 1271～1360nm 1550nm	≤3.5 ≤5.3 ≤18	ps/(nm.km) ps/(nm.km) ps/(nm.km)
Zero dispersion wavelength		1300～1324	nm
PMD	Link value	≤0.2	Ps/km1/2
Max zero dispersion slope		≤0.093	ps/(nm2.km)
Group index of eefraction (Typical value)	1310nm 1550nm	1.466 1.467
Geometric Characteristics
Cladding diameter		125.0±1.0	µm
Core/Cladding concentricity error		≤0.8	µm
Cladding non-circularity		≤1.0	%
Coating diameter		245.0±10	µm
Cladding/Coating concentricity error		≤12.0	µm
Coating non-circularity		≤8	%
Diameter of colored coating		250.0±15	µm
Mechanical Characteristics
Curling (Radius)		≥4	m
Proof stress		≥0.69	Gpa
Coating strip force	Average value peak value	1.0-5.0 1.3-8.9	N N
Dynamic stress corrosion susceptibility parameter (nd Value)		≥20

4. Optical Fiber Cable

4.1 Duct cable structure  (Type: GYFTY)
- G.652 D fibers
- Central non-metallic strength element
- Loose tubes SZ-stranded
- Filling compound 
- MDPE outer sheath

4.2 Manufacture process
Coloring of fiber
At first, the fibers should be colored different colors for identification in loose tube.

Loose tube technique
The material of loose tube is PBT (Polybutylene terephthalate). Each loose tube contains fibers, which are loosely lying in the tube. The tube is filled with a non-hygroscope, non-toxic, homogenous gel in order to prevent water penetration.

Reverse lay (SZ) stranding cable core
The loose tubes are stranded around the central strength member according to the reverse lay method, which means that the direction of stranding will reverse every several stranding pitch. Polyester binder in enlaced around the tube in order to retain them in the proper position.

Cable sheath
Then the MDPE is extruded over the water-blocking tape to act as outer sheath. 

4.3 Fiber and loose tube color code

Fiber color code:

NO.	Color		NO.	Color		NO.	Color		NO.	Color
1	BL- Blue		2	OR- Orange		3	GR- Green		4	BR- Brown
5	GY- Grey		6	WH- White		7	RE- Red		8	BK- Black
9	YE- Yellow		10	PU- Purple		11	PI- Pink		12	AQ- Aqua

Loose tube color code:

NO.	Color		NO.	Color		NO.	Color		NO.	Color
1	BL- Blue		2	OR- Orange		3	GR- Green		4	BR- Brown
5	GY- Grey		6	WH- White		7	RE- Red		8	BK- Black
9	YE- Yellow		10	PU- Purple		11	PI- Pink		12	AQ- Aqua

Color-coding of fiber and tube will be clear, and not fade and move in temperature of  working 
and installation. 

4.4 Technical parameter of cable

Parameters		Specifications
Tensile strength	Short time (Installation)	1500N
Crush resistance	Short time (Installing)	1500N/100mm
Temperature range	Installation	-10~+50℃
	Operation	-40~+60℃
Minimum bending radius	Dynamic	20 times of cable diameter
	Static	10 times of cable diameter

4.5 Section of cable

4.6 Construction of cable

Parameters		Specifications
Approx. cable diameter		9.8mm
Approx. cable weight		90kg/km
Central tensile element	Material	Non-metallic element (FRP)
	Diameter	2.8mm
Fiber	Type	ITU-TG.652 D
	Number	4~144
Tube filling	Material	Tube filling compound
Loose tube	Material	PBT (Polybutylene terephthalate)
	Outer diameter	1.9mm
	Number	2~12
Filler	Material	Polyethylene
	Number	2
Outer sheath	Material	MDPE
	Thickness	Nominal: 1.8mm; minimum: 1.6mm

5. Testing Requirements

5.1 Mechanic performance:

Item	Requirements
Tension	Test standard	IEC 60794-1-2-E1
	Length of cable under load	Not less than 50 meters
	Diameter of mandrel	Not more than 30x outside diameter of cable
	Load	See 4.4 Technical parameter of cable
	Load time	1 min
	Tension rate	10 mm/min
	Test result	Additional attenuation: <0.1dB
		No fiber break and no sheath damage
Impact resistance	Test standard	IEC 60794-1-2-E4
	Impact energy	4.4N·m
	Radius of hammer	12.5mm
	Length of cable under test	Not less than 50 mm
	Number of impacts	Not less than 5 times
	Impact rate	Not more than 2 sec/cycle
	Test result	Additional attenuation: <0.1dB
		No fiber break and no sheath damage
Crush	Test standard	IEC 60794-1-2-E3
	Load	See 4.4 Technical parameter of cable
	Load time	10 min.
	Test result	Additional attenuation: <0.1dB
		No fiber break and no sheath damage
Repeat bending	Test standard	IEC 60794-1-2-E8
	Diameter of mandrel	20x outside diameter of cable
	Load	50N
	Number of cycles	Not less than 25 cycles
	Flexing rate	Not more than 2 sec/cycle
	Test result	Additional attenuation: <0.1dB
		No fiber break and no sheath damage
Twist	Test standard	IEC 60794-1-2-E7
	Twist rate	Not more than 1min/cycle
	Twist angle	±180º
	Number of cycles	10 cycles
	Load	50N
	Test result	Additional attenuation: <0.1dB
		No fiber break and no sheath damage
Cable bending	Test standard	IEC 60794-1-2-E11B
	Diameter of mandrel	20x outside diameter of cable
	Number of cycles	3
	Test result	Additional attenuation: <0.1dB
		No fiber break and no sheath damage

5.2 Environment performance:

Item	Requirement
Temperature cycling	Testing standard	IEC 6094-1-2-F1
	Variation of temperature	-40~+60℃
	Number of cycles	2
	Soak time	12 hours
	Test result	Additional attenuation:<0.1dB
		No fiber break and no sheath damage
Water penetration	Testing standard	IEC 60794-1-2-F5
	Height of water column	1 meter
	Test time	24 hours
	Sample length	3 meters
	Test result	At the ;end of 24 hours, no water leaks from the opposite end of the cable
Compound drip	Testing standard	IEC 60794-1-2-E14
	Temperature	+70℃
	Sample length	30cm
	Soak time	24 hours
	Test result	Weightiness of the cable specimens is decreased less than or equal to 0.005g.

6. Cable Marking

6.1 Sheath mark
Unless otherwise required the sheath will be marked at intervals of 1m, containing:
(a) Indication in meters
(b) Quantity and type of fibers
(c) Factory name
(d) Date of manufacturing (year)
(e) Other requirements

The marks will be permanent and legible for the duration of the cable life.  
The precision of the length indication will be better than 1000m±2m.

7. Delivery Requirements
Normal cable factory length: from 2000m to 6000m or other required.
All cables will be delivered on drums with protection of both ends of the cable. Each drum will 
have a waterproof mark, with clear factory name, date, cable type, cable length in unit gross
weight, cable outer diameter, cable weight and so on and will be provided the length of all 
fibers in each drum.

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