Optical fiber cable with dual layer buffer tube for microduct application

An optical fiber cable comprising:

• a central strength member lying substantially along a longitudinal axis of the optical fiber cable, wherein the central strength member is formed of fiber reinforced plastic, wherein the central strength member has a diameter of about 3.0 mm;
• a first layer wrapped helically around the central strength member, wherein the first layer is formed of a plurality of water swellable yarns;
• a plurality of buffer tubes stranded helically around the first layer, wherein each of the plurality of buffer tubes encloses a plurality of optical fibers,
• wherein each of the plurality of buffer tubes has a first diameter of about 1.55 mm±0.05 mm, wherein each of the plurality of buffer tubes has a second diameter of about 1.85 mm±0.05 mm,
• wherein each of the plurality of buffer tubes is formed of a combination of two sub layers having different material, wherein each of the plurality of buffer tubes has a first sub layer and a second sub layer;
• wherein the first sub layer is formed of polycarbonate, wherein the second sub layer is formed of polybutylene terephthalate;
• a second layer, wherein the second layer cross helically surrounds a core of the optical fiber cable, wherein the second layer is formed of a pair of binder yarns, wherein the pair of binder yarns comprising:
• a first binder yarn, wherein the first binder yarn is wrapped helically in clockwise direction;
• and
• a second binder yarn, wherein the second binder yarn is wrapped helically in anti-clockwise direction;
• a third layer wrapped helically around the core of the optical fiber cable, wherein the third layer is formed of a plurality of water swellable yarns;
• and
• a fourth layer surrounding the third layer, wherein the fourth layer is formed of high density polyethylene, wherein the fourth layer has a thickness in a range of about 0.4 mm to 0.6 mm, wherein the fourth layer has a density in a range of about 0.90 gm/cm3 to 0.96 gm/cm3,
• wherein the optical fiber cable has a diameter of about 7.7 mm±0.2 mm.

An optical fiber cable comprising:

• a central strength member lying substantially along a longitudinal axis of the optical fiber cable, wherein the central strength member is formed of fiber reinforced plastic, wherein the central strength member has a diameter of about 3.0 mm;
• a first layer wrapped helically around the central strength member, wherein the first layer is formed of a plurality of water swellable yarns;
• a plurality of buffer tubes stranded helically around the first layer,
• wherein each of the plurality of buffer tubes has a first diameter of about 1.55 mm±0.05 mm, wherein each of the plurality of buffer tubes has a second diameter of about 1.85 mm±0.05 mm,
• wherein each of the plurality of buffer tubes is formed of a combination of two sub layers having different material, wherein each of the plurality of buffer tubes has a first sub layer and a second sub layer;
• wherein the first sub layer is formed of polycarbonate,
• wherein the first sub layer has a thickness of about 75 microns±10 microns, wherein the first sub layer has a density of about 1.2 gm/cm3,
• wherein the second sub layer is formed of polybutylene terephthalate, wherein the second sub layer has a thickness of about 75 microns±10 microns, wherein the second sub layer has a density of about 1.31 gm/cm3,
• wherein each of the plurality of buffer tubes encloses a plurality of optical fibers, wherein the plurality of buffer tubes is eight, wherein the plurality of optical fibers in each of the plurality of buffer tubes is twenty four, wherein each of the plurality of optical fibers has a diameter of about 250 microns;
• a second layer, wherein the second layer cross helically surrounds a core of the optical fiber cable, wherein the second layer is formed of a pair of binder yarns, wherein the pair of binder yarn comprising:
• a first binder yarn, wherein the first binder yarn is wrapped helically in clockwise direction;
• and
• a second binder yarn, wherein the second binder yarn is wrapped helically in anti-clockwise direction;
• a third layer wrapped helically around the core of the optical fiber cable, wherein the third layer is formed of a plurality of water swellable yarns;
• and
• a fourth layer surrounding the third layer, wherein the fourth layer is formed of high density polyethylene, wherein the fourth layer has a thickness in a range of about 0.4 mm to 0.6 mm, wherein the fourth layer has a density in a range of about 0.90 gm/cm3 to 0.96 gm/cm3,
• wherein the optical fiber cable has a diameter of about 7.7 mm±0.2 mm.