Loose Tube or Tight Buffered?

Posted by in Leader Blog on May 16, 2013 . 0 Comments.


Loose Tube or Tight Buffered Cable?
Loose Tube
Loose tube contains 250um fibres which are often surrounded by gel and contained within a central tube or multiple of tubes around a central strength member. An aramid yarn is layered between the fibre tubes and the outer jacket(s). Central loose tube is commonly up to 24 fibres whereas multi-loose tube is normally reserved for larger core counts such as 72 and 144 fibres. 
Outer jackets are often of a U-LSOH material where they can be used within external ducts and continue the runs inside the building. However, PE jackets are considered to be more suitable as the jacket is more resistant to scuffing or damage.
Loose tube for outdoor conditions
Water Resistant – By utilising gel filled tubes and water swelling tapes, loose tube cable provide maximum protection against water penetration and migration. 
UV Resistant Outer jacket contains carbon black which provides UV protection for applications involving exposure to direct sunlight.
Mechanical Resistant – To provide additional robustness, an armoured layer can be provided. CST (corrugated steel tape), SWA (steel wire armour) or GRP (glass reinforced plastic) allow the cables to be protected in harsher environments and make them suitable for direct burial.
Lower cost – As these cables contain 250um fibres, loose tube generally are less expensive than those made to a tight buffered construction.
Duct space – Due to their construction loose tube cables will take less duct space than tight buffered cables especially for higher fibre counts contributing to overall lower installation costs
Tight Buffered
Contains 24 x 900um fibres, bundled and often surrounded by an aramid yarn and covered with the outer jacket(s). 
The 900um fibre is available in two options:
Semi-loose buffer is a 125um fibre coated with a 250um and housed within a 900um outer shell. The benefit of this is that with the correct stripping tools, up to 1 metre of the 250um fibre can be exposed in a single action allowing easy splicing and fibre management within a splice cassette.
Tight buffer is 125um coated with 250/500/900um layers which is better suited to direct termination of the connectors.
Typical use of tight buffered cables is for premise networking. The 900um jacket makes the handling of each core easier and is less fragile than 250um.
Tight Buffered for indoor conditions
No need for gel – Indoor application eliminates the need to use protective gel allowing them suitable for installing vertically through building risers
Flexibility – No stiff strength member is needed, making the cable more flexible. The cable is also ‘tight bound’ allowing it to be pulled around multiple bends or hung vertically without causing ‘fibre axial migration’.
Aramid Yarns – The most popular aramid yarns used in fibre optic cables are e-glass or Kevlar®. E-glass is primarily used for measures against rodent damage as the e-glass splinters when severed. Kevlar®, although light in weight offers excellent mechanical protection against crushing or straining.
Tags: multi-core, cable, loose tube, tight buffered Last update: Dec 01, 2016


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