Page 218 - The ROV Manual - A User Guide for Remotely Operated Vehicles 2nd edition

Optical Fiber, 1:
Corning SMF-28TM with 200 kpsi proof-test and a 900μm diameter buffer made from a proprietary high modulus material
KevlarTM 29 yarns parallel around fiber-optic
Power conductors, 6:
#26 AWG (19 × 0.004 in.) Tin-plated copper with 600V rated insulation made from TefzelTM
DC resistance at 20°C: <=42 Ω/1000–ft
Note: 3 #26= 1 #22
Black outer jacket: 0.20 in. nominal wall made from cellular LDPE with 0.60 gm/cc nominal SG
Strength membrane: counter-wound layers made from KevlarTM type 49 yarns
Polyurethane jacket: 0.03 in. nominal wall
Water blocking and tape wrap binder
Example positively buoyant (floats)
8.8 Underwater cable design 207
FIGURE 8.50
Positively buoyant cable.
Overall diameter Density
Hardness
Breaking strength Breaking strength
Peak tension load Minimum bend diameter Storage hub diameter Hydrostatic pressure
= 0.65 inches nominal = 0.73 gm/cc nominal = 87 Shore A nominal = 5000 lbs minimum = 6000 lbs maximum = 1375 lbs maximum = 12 inches
= 18 inches = 710 psig
for emergency field repairs and unforeseen system expansion requirements. However, the weight of these spare conductors must be considered in the neutral buoyancy equation for a vehicle’s flying tether.
8.8.12 Interconnect cables
The preceding discussion on Power and Signal applies equally to interconnect cables.
Portable cords are often used underwater for power or signal cable. They are available in either thermoset or thermoplastic constructions. Thermoset rubber material hardens or “sets” under direct application of heat, called “curing,” and once it sets, it is not able to be resoftened by heating.
Thermoset is a much more durable compound than thermoplastic.
(Courtesy Falmat.)